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Journal of Systematic Palaeontology
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A new early dinosaur (Saurischia: Sauropodomorpha) from the Late
Triassic of Argentina: a reassessment of dinosaur origin and phylogeny
Martin D. Ezcurra
a
a
Laboratorio de Anatomía Comparada y Evolución de los Vertebrados, Museo Argentino de Ciencias
Naturales 'Bernardino Rivadavia', Buenos Aires, Argentina
Online publication date: 30 July 2010
To cite this Article Ezcurra, Martin D.(2010) 'A new early dinosaur (Saurischia: Sauropodomorpha) from the Late Triassic
of Argentina: a reassessment of dinosaur origin and phylogeny', Journal of Systematic Palaeontology, 8: 3, 371 — 425
To link to this Article: DOI: 10.1080/14772019.2010.484650
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Journal of Systematic Palaeontology, Vol. 8, Issue 3, September 2010, 371–425
A new early dinosaur (Saurischia: Sauropodomorpha) from the Late Triassic
of Argentina: a reassessment of dinosaur origin and phylogeny
Martin D. Ezcurra
∗
Laboratorio de Anatom
´
ıa Comparada y Evoluci
´
on de los Vertebrados, Museo Argentino de Ciencias Naturales ‘Bernardino Rivadavia’,
Av. Angel Gallardo 470 (C1405DJR), Buenos Aires, Argentina
(Received 8 December 2008; accepted 1 April 2010)
It was traditionally thought that the oldest known dinosaur assemblages were not diverse, and that their early diversification
and numerical dominance over other tetrapods occurred during the latest Triassic. However, new evidence gathered from
the lower levels of the Ischigualasto Fm. of Argentina challenges this view. New dinosaur remains are described from
this stratigraphical unit, including the new species Chromogisaurus novasi. This taxon is distinguished from other basal
dinosauriforms by the presence of proximal caudals without median notch separating the postzygapophyses, femoral lateral
surface with deep and large fossa immediately below the trochanteric shelf, and metatarsal II with strongly dorsoventrally
asymmetric distal condyles. A phylogenetic analysis found Chromogisaurus to lie at the base of Sauropodomorpha, as a
member of Guaibasauridae, an early branch of basal sauropodomorphs composed of Guaibasaurus, Agnosphitys, Panphagia,
Saturnalia and Chromogisaurus. Such an affinity is for the first time suggested for Guaibasaurus, whereas Panphagia is
not recovered as the most basal sauropodomorph. Furthermore, Chromogisaurus is consistently located as more closely
related to Saturnalia than to any other dinosaur. Thus, the Saturnalia + Chromogisaurus clade is named here as the new
subfamily Saturnaliinae. In addition, Eoraptor is found to be the sister-taxon of Neotheropoda, and herrerasaurids to be
non-eusaurischian saurischians. The new evidence presented here demonstrates that dinosaurs first appeared in the fossil
record as a diverse group, although they were a numerically minor component of faunas in which they occur. Accordingly,
the early increase of dinosaur diversity and their numerical dominance over other terrestrial tetrapods were diachronous
processes, with the latter preceded by a period of low abundance but high diversity.
Keywords: dinosaur origin; Saurischia; Sauropodomorpha; Late Triassic; Ischigualasto Formation; Argentina
Introduction
Dinosaurs are among the most important group of terres-
trial tetrapods, and their origin is a widely discussed topic.
They originated in the Middle or early Late Triassic, with
the oldest representatives collected from Carnian beds of
Argentina, Brazil and India (Reig 1963; Colbert 1970; Chat-
terjee 1987; Sereno & Novas 1992; Sereno et al. 1993;
Langer et al. 1999; Langer 2005a; Martinez & Alcober
2009), dated to about 231 Ma (Rogers et al. 1993; Furin
et al. 2006). At the moment, the few assemblages contain-
ing the oldest known dinosaurs depicted low dinosaur abun-
dance and diversity; and their diversification and numeri-
cal dominance over other tetrapod groups is first seen in
younger beds of Norian age (latest Late Triassic) (Benton
1988, 2006; Bonaparte 1982; Novas 1997). The traditional
view is that the early diversification and numerical increase
of dinosaurs occurred almost simultaneously during the
latest Late Triassic (post-Carnian times) (Benton 1988,
1991, 1993, 2006; Bonaparte 1982; Charig 1984; Novas
1997; Brusatte et al. 2008a). One model postulates that the
∗
Email: martindezcurra@yahoo.com.ar
replacement of archaic tetrapods by dinosaurs and other
modern groups was a long, drawn-out process involving
competition (Bonaparte 1982; Charig 1984; Novas 1997).
On the other hand, it has been claimed that the early radi-
ation of dinosaurs occurred opportunistically in an empty
ecospace, cleared during the end-Carnian extinction event
(Benton 1988, 1991, 1993).
In recent years, new discoveries have changed our
understanding of the evolution of the immediate precur-
sors of dinosaurs. It has been shown that non-dinosaurian
dinosauromorphs survived well into the Late Triassic, coex-
isting with early dinosaurs (Ezcurra 2006; Irmis et al. 2007).
This suggests that the transition between assemblages with
dinosaur precursors and those composed exclusively of
dinosaur dinosauromorphs was gradual, and models of
rapid competitive or fortuitous replacement are incorrect
(Irmis et al. 2007), at least in North America. However, our
understanding of the origin of dinosaurs is mostly based
on a few discoveries made during recent decades (Sereno
& Novas 1992; Sereno et al. 1993; Langer et al. 1999;
Martinez & Alcober 2007, 2009; Ezcurra 2008). Here,
ISSN 1477-2019 print / 1478-0941 online
Copyright
C
2010 The Natural History Museum
DOI: 10.1080/14772019.2010.484650
http://www.informaworld.com
Downloaded By: [Ezcurra, Martín Daniel] At: 14:41 31 July 2010
372 M. D. Ezcurra
I describe new dinosaur remains from the Ischigualasto
Formation (late Carnian–middle Norian; Rogers et al.
1993; Furin et al. 2006) of Argentina. This new evidence
demonstrates that the numerical increase and diversifica-
tion of early dinosaurs were diachronous processes, with
dinosaur dominance (high abundance) preceded by a period
of low abundance but high diversity prior or close to the
Carnian–Norian boundary.
The Ischigualasto Fm. contains a diverse tetrapod fauna,
but this stratigraphical unit is best known because it is one
of the oldest known dinosaur-bearing assemblages (Sereno
& Novas 1992; Benton 1993; Rogers et al. 1993; Langer
2005a, b). The lower third of the Ischigualasto Fm. (late
Carnian) preserves the remains of the basal saurischian
dinosaurs Herrerasaurus, Eoraptor and Panphagia (Reig
1963; Sereno & Novas 1992; Sereno et al. 1993; Martinez
& Alcober 2009), and two or three new dinosaur species
(Martinez & Alcober 2007; Ezcurra & Novas 2007a, 2008;
Ezcurra 2008), one of them named here as Chromogisaurus
novasi nov. gen. et nov. sp.
Geological, palaeontological and
chronostratigraphical settings
The holotype of Chromogisaurus novasi (PVSJ 845) was
found in the autumn of 1988 during a joint field trip to
the Ischigualasto Fm. carried out by the Museo Argentino
de Ciencias Naturales ‘Bernardino Rivadavia’, the Univer-
sidad Nacional y Museo de San Juan and the University
of Chicago. This stratigraphical unit crops out in the San
Juan and La Rioja provinces of NW Argentina, as part
of the Agua de la Pe
˜
na Group of the Ischigualasto-Villa
Uni
´
on Basin (Bossi 1971). It lies between the Los Rastros
Fm. (Ladinian-early Carnian) below and the Los Colorados
Fm. (Norian) above. The Ischigualasto Fm. is composed of
abundant fluvial-channel sandstones, overbank mudstones
and paleosols (Currie et al. 2009). Deposition occurred in a
north-west-trending continental rift basin on an upland allu-
vial plain dominated by low sinuosity, shallow streams and
occasional lakes, within a seasonal climatic regime (Rogers
et al. 1993; Currie et al. 2009). At the south-eastern end of
the Ischigualasto Basin, the Ischiguaslto Fm. progressively
thins from approximately 700 m in the west to 400 m in the
east, over a distance of 7 km (Currie et al. 2009). Currie
et al. (2009) reviewed the stratigraphy of the Ischigualasto
Fm. in detail, recognizing four different members for the
south-eastern end of the Ischigualasto Basin (Ischigualasto
Provincial Park), from the lowermost to the uppermost: the
La Pe
˜
na, Cancha de Bochas, Valle de la Luna and Quebrada
de la Sal members.
Good chronostratigraphical control is currently avail-
able for the Ischigualasto Fm. Sanidine crystals from a
bentonite sampled approximately 80 m above the base of
the formation (Cancha de Bochas Member) (Currie et al.
2009) yielded an
40
Ar/
39
Ar date of 227.8 ± 0.3 Ma (Rogers
et al. 1993). This dating was performed in Section 2 of the
formation sensu Currie et al. (2009), which exceeds 400
m in thickness, thus the age dating of Rogers et al. (1993)
belongs to the lower sector of the unit. However, there is
a discrepancy between U-Pb and
40
Ar/
39
Ar dates, the latter
being 0.5–1% younger (Schoene et al. 2006). Following this
discrepancy, Furin et al. (2006) recalculated the age dating
obtained by Rogers et al. (1993) to be about 230.3–231.4 ±
0.3 Ma. In addition, the Late Triassic timescale has suffered
recent modifications. Muttoni et al. (2004), based on recent
radiometric datings applied to biostratigraphically dated
marine deposits, suggested that the Late Triassic, and in
particular the Norian, are considerably longer than previ-
ously accepted, with durations of approximately 35 and
20 myrs respectively. As a result, Muttoni et al. (2004)
placed the Carnian–Norian boundary at 228 Ma. These
re-calibrations of the Late Triassic timesacale, as well as
corrected dating of the lower Ischigualasto bentonite ash,
indicate that the deposition of the sedimentary unit began
approximately 231 Ma during the late Carnian.
Another age dating has been performed by Shipman
(2004) on plagioclase crystals from a bentonite ash, approx-
imately 610 m from the base of the formation (following
Currie et al. 2009, fig. 3) (top of the Valle de la Luna
Member, Section 1 of Currie et al. 2009). This dating
yielded an
40
Ar/
39
Ar date of 217.0 ± 1.7 Ma (Shipman
2004). Nevertheless, following the corrections introduced
by Schoene et al. (2006), the recalculated age obtained
by Shipman (2004) is about 219.4–220.4 ± 1.7 Ma. This
age locates the top of the Valle de la Luna Member of the
Ischigualasto Fm. in the mid-Norian (sensu Muttoni et al.
2004). Accordingly, following the recalculated age datings
of Rogers et al. (1993) and Shipman (2004), and the modi-
fied Late Triassic timescale of Muttoni et al. (2004), the
Carnian–Norian boundary should be located close to the
middle of the formation probably within the Valle the la
Luna Member.
The type specimen of Chromogisaurus novasi (PVSJ
845) was excavated from the north of the Valle Pintado
locality, in lower levels of the Cancha de Bochas Member
(sensu Currie et al. 2009) of the Ischigualasto Fm. (Section
3ofCurrieet al. 2009, Ischigualasto National Park,
San Juan Province) (Fig. 1). The Valle Pintado local-
ity exposes the lower third of the formation, very close
to the Herr Toba bentonite level dated by Rogers et al.
(1993). This considered, the holotype of Chromogisaurus
is late Carnian in age. It was found in a very fossilifer-
ous grey mudstone, in the same layer (approximately three
metres thick) from which were collected a specimen of the
herrerasaurid Herrerasaurus ischigualastensis (PVSJ 380)
and a cynodont jaw (F. Novas unpublished field trip notes).
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A new early dinosaur and reassessment of dinosaur origin and phylogeny 373
Figure 1. Map of SE Agua de la Pe
˜
na Group (San Juan and La Rioja provinces, NW Argentina), showing the type locality of Chromo-
gisaurus novasi (modified from Alcober 1996).
The lower third of the Ischigualasto Fm. contains
a rich fossil tetrapod fauna including temnospondyls
(Pelorocephalus ischigualastensis and Promastodonsaurus
bellmanni), rhynchosaurs (Hyperodapedon sanjuanensis
and H. mariensis), dicynodonts (Ischigualastia jenseni),
cynodonts (Exaeretodon frenguellii, Ischignathus sudamer-
icanus, Ecteninion lunensis, Chiniquodon sanjuanensis and
cf. Probainognathus sp.), crurotarsan archosaurs (Sauro-
suchus galilei, Aetosauroides scagliai, Sillosuchus long-
icervix and Trialestes romeri) and dinosaurs. Hitherto, only
three dinosaur species have been recorded in the lower
third of the unit (Herrerasaurus ischigualastensis, Eorap-
tor lunensis and Panphagia protos). Two probably new
herrerasaurian species are also present in the lower levels
of the unit (Ezcurra & Novas 2007a, 2008; Martinez &
Alcober 2007). Pisanosaurus mertii (Casamiquela 1967;
Bonaparte 1976) and a new theropod species (Martinez
et al. 2008) are known from the middle of the Ischigualasto
Fm.
The assemblage in the lower third of the Ischigualasto
Fm. is dominated by the rhynchosaur Hyperodapedon,
followed by the cynodont Exaeretodon (Bonaparte 1982;
Benton 1983; Rogers et al. 1993). The same pattern occurs
in the Hyperodapedon Acme Zone of the Santa Maria Fm.
of Brazil (Langer 2005b; Langer et al. 2007a), which has
formed the basis for correlating the two assemblages bios-
tratigaphically.
Institutional abbreviations
GR: Ghost Ranch Ruth May Museum of Paleontology,
New Mexico, USA; ISIR: Geological Studies Unit of
the Indian Statistical Institute, Calcutta, India; MACN-
Pv: Museo Argentino de Ciencias Naturales ‘Bernardino
Rivadavia’, Paleontologia de Vertebrados, Buenos Aires,
Argentina; MB: Museum fur Naturkunde der Humboldt
Universitat, Berlin, Germany; MCN: Museu de Cien-
cias Naturais da Fundacao Zoobotanica do Rio Grande
do Sul, Porto Alegre, Brazil; MCP: Museo de Ciencias
e Tecnolog
´
ıa, Porto Alegre, Brazil; MCZ: Museum of
Comparative Zoology, Cambridge, USA; MLP: Museo
de La Plata, La Plata, Argentina; NHM: Natural History
Museum, London, UK; PEFO: Petrified Forest National
Park, Arizona, USA; PULR: Paleontolog
´
ıa, Universidad
Nacional de La Rioja, La Rioja, Argentina; PVL: Pale-
ontolog
´
ıa de Vertebrados, Instituto ‘Miguel Lillo’, San
Miguel de Tucum
´
an; PVSJ:Divisi
´
on de Paleontologia de
Vertebrados del Museo de Ciencias Naturales y Univer-
sidad Nacional de San Juan, San Juan, Argentina; SAM:
South African Museum, South Africa; SMNS: Staatliches
Museum fur Naturkunde, Stuttgart, Germany; UCMP:
University of California Museum of Paleontology, Berke-
ley, CA, USA; UFRGS: Universidade Federal de Rio
Grande do Sul, Porto Alegre, RS, Brazil; UMMP:Univer-
sity of Michigan Museum of Paleontology, Ann Arbor, MI,
USA; QG: Zimbabwe Natural History Museum, Bulawayo,
Zimbabwe; ZPAL: Institute of Paleobiology of the Polish
Academy of Sciences, Warsaw, Poland.
Systematic palaeontology
Dinosauria Owen, 1842
Saurischia Seeley, 1888
Sauropodomorpha von Huene, 1932
Guaibasauridae Bonaparte et al., 1999
Downloaded By: [Ezcurra, Martín Daniel] At: 14:41 31 July 2010
374 M. D. Ezcurra
Figure 2. Preserved bones of Chromogisaurus novasi (PVSJ 845). Scale bar = 50 cm.
Definition. The family Guaibasauridae is defined here as
all archosaurs more closely related to Guaibasaurus cande-
lariensis Bonaparte et al., 1999 than to Carnotaurus sastrei
Bonaparte, 1985 or Saltasaurus loricatus Bonaparte &
Powell, 1980.
Saturnaliinae new taxon
Definition. The subfamily Saturnaliinae is defined here as
Saturnalia tupiniquim Langer et al., 1999, Chromogisaurus
novasi nov. gen. et nov. sp., and all the descendants from
their most common ancestor.
Chromogisaurus novasi gen. et sp. nov.
(Figs 2–13, 14B, D, F, 16B, 17C)
Etymology. The generic name is derived from the Greek
words chroma (colour, paint), gi (ground, land) and saurus
(reptile); in allusion to the Valle Pintado (Painted Valley)
locality of the Ischigualasto Fm. in which the new taxon
was found. The specific name is in honour of Dr. Fernando
Novas, for his outstanding research on early dinosaur evolu-
tion.
Holotype. PVSJ (Paleontologia de Vertebrados Museo de
San Juan) 845, partial skeleton including a proximal caudal
vertebra, a mid-caudal vertebra, proximal end of the right
ulna, right ilium, a probable fragment of ischial shaft, both
femora, left tibia, left fibula, left metatarsals II and V, pedal
phalanges, including a complete left digit II and some
unidentified bone fragments (Fig. 2; Tables 1, 2).
Locality and horizon. Lower levels of the Cancha de
Bochas Member (sensu Currie et al. 2009) of the
Ischigualasto Fm. (Late Triassic: late Carnian, 230.3–
231.4 ± 0.3 Ma; Rogers et al. 1993; Furin et al. 2006),
northern margin of Valle Pintado site (Section 3 of Currie
et al. 2009), Agua de la Pe
˜
na Group, Ischigualasto-
Villa Uni
´
on Basin, Ischigualasto National Park, San Juan
Province, Argentina (Fig. 1).
Diagnosis. Chromogisaurus novasi is a small basal
saurischian dinosaur diagnosed by the following combina-
tion of characteristics (autapomorphies
∗
): proximal caudals
without median notch separating the postzygapophyses;
ilium with strongly posteriorly developed postacetabu-
lar process; incipiently perforated acetabulum; a femoral
lateral surface with deep and large fossa immediately below
the trochanteric shelf;
∗
and a metatarsal II with strongly
dorsoventrally asymmetric distal condyles.
Description
The size of the appendicular elements (Table 2) of the
holotype of Chromogisaurus closely matches that of
Saturnalia (MCP 3844-PV, 3846-PV, Langer 2003) and
Table 1. Selected measurements (in millimetres) of axial and
forelimb elements of Chromogisaurus novasi gen. et sp. nov.
Abbreviations:
∗
= incomplete.
Measurements
Element of PVSJ 845
Proximal caudal vertebra
Maximum length (neural arch) 29.7
Maximum height (centrum + neural arch) 28
∗
Length of centrum 24.7
Anterior height of centrum 14.9
Anterior width of centrum 12.3
Posterior height of centrum 13.6
Posterior width of centrum 12.5
Maximum width of transverse process 18.1
Mid-caudal vertebra
Maximum length (neural arch) 31.6
∗
Maximum height (centrum + neural arch) 38.7
Length of centrum 25.4
Anterior height of centrum 11.8
∗
Anterior width of centrum 6.9
∗
Posterior height of centrum 12.6
Posterior width of centrum 8.1
Right ulna
Maximum length 29.6
∗
Maximum width 11.8
Length of olecranon 20.7
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A new early dinosaur and reassessment of dinosaur origin and phylogeny 375
Table 2. Selected measurements (in millimetres) of pelvic
girdle and hindlimb available bones of Chromogisaurus novasi
gen. et sp. nov. Abbreviations:
∗
= incomplete; () = estimated;
∼=deformed. The estimated lengths of the complete elements
are based on extrapolations with Saturnalia tupiniquim
(following the measurements of Langer 2003).
Measurements of
PVSJ 845
Element Left Right
Ilium
Maximum length — 96.4
∗
Maximum length along iliac blade — 75.7
∗
Maximum length along pedicles — 53.9
∗
Maximum height — 61.5
Maximum width of the supraacetabular
crest
—15.5
Length of the postacetabular process — 49.9
Length between pubic and ischiadic
embayments
—28.2
Femur
Maximum preserved length 48.0
∗
160
∗
Maximum depth (anteroposteriorly) at 19.119.7
level of the 4th trochanter
Maximum length of the lateral fossa 24.024.1
Circumference below 4th trochanter 56 —
Tibia
Length — 175
Maximum proximal depth
(anteroposteriorly)
—41.8
Maximum proximal width (lateromedially) — 14.4 ∼
Maximum distal depth (anteroposteriorly) — 19.1
Maximum distal width (lateromedially) — 13.9 ∼
Fibula
Maximum preserved length — 114.9
∗
Maximum preserved proximal depth — 21.0
∗
Depth at mid-length — 10.6
Width at mid-length — 5.8
Metatarsal II
Maximum preserved length 58.0
∗
(70) —
Distal width 12.8—
Maximum height of medial condyle 8.6—
Maximum height of lateral condyle 10.6—
Metatarsal V
Preserved length 38.5—
Proximal width 10.3—
Proximal depth 6.5—
Distal width 2.1—
Phalanx II-1
Length 19.6—
Maximum proximal height 7.0—
Maximum proximal width 12.2—
Maximum distal height 5.7—
Maximum distal width 8.7—
Phalanx II-2
Length 17.1—
Maximum proximal height 6.1—
Maximum proximal width 10.1—
Maximum distal height 4.6—
Maximum distal width 7.4—
Phalanx II-3 (ungual)
Length 17.8
∗
—
Maximum proximal height 7.7—
Maximum proximal width 6.9—
Eoraptor (PVSJ 512), indicating that it was a small animal
of around 2 metres long (Fig. 2), with an approximate mass
of 10 kg (following the regression of Anderson et al. 1985).
The preserved caudal vertebrae present fully closed neuro-
central sutures, suggesting that the specimen is not a young
juvenile (Irmis 2007).
Caudal vertebrae. A proximal and a mid-caudal verte-
bra are preserved (Figs 3, 4; Table 1). The centrum of the
mid-caudal vertebra is slightly longer than that of the prox-
imal vertebra, but the proximal caudal centrum is taller.
The length of the centrum of the proximal caudal verte-
bra is 1.5 times its height (Fig. 3A, D). The centrum is
strongly compressed laterally at mid-length, and hourglass-
shaped in ventral view. The ventral surface of the centrum
is convex, without a ventral groove. Both anterior and
posterior articular surfaces are concave and oval, with
their major axis dorsoventrally oriented (Fig. 3B, E). In
the neural arch, the walls of the neural canal are low.
The left transverse process is almost completely preserved,
only lacking its distal tip, and it is dorsolaterally oriented,
as also occurs in Panphagia (Martinez & Alcober 2009).
The transverse process is elongated, representing 82% of
the length of the centrum as preserved (Fig. 3C, F). The
transverse process curves gently anteriorly, with concave
and convex anterior and posterior margins, respectively.
The latter condition is also observed in Saturnalia (MCP
3846-PV), but is absent in Guaibasaurus (UFRGS PV
0725T), Herrerasaurus (PVL 2556), Eoraptor (PVSJ 512)
and neotheropods (e.g. Dilophosaurus; UCMP 37302).
The prezygapophyses are damaged, but it is possible to
see that they extended only slightly beyond the anterior
end of the centrum. The articular surface of the prezy-
gapophysis is laterodorsally oriented. The postzygapophy-
ses are much better preserved, with lateroventrally oriented
articular surfaces, extending slightly beyond the poste-
rior end of the centrum. No hyposphene-hypantrum artic-
ulation complex is present, contrasting with the proxi-
mal and mid-caudal vertebrae of basal neotheropods (e.g.
Dilophosaurus, Lophostropheus; UCMP 37302, Ezcurra
& Cuny 2007). No median notch separates the postzy-
gapophyses from each other. In contrast, in Saturnalia
(MCP 3846-PV) and Guaibasaurus (UFRGS PV 0725T)
the postzygapophyses are separated by a deep median notch.
A well developed and sharp prezygo-postzygopophyseal
lamina is present.
The centrum of the mid-caudal vertebra is two times
longer than the height of its posterior articular facet (Fig.
4A, B, E, F). The anterior articular surface of the centrum is
not preserved (Fig. 4G, H). The posterior articular surface
is strongly concave and oval, with its major axis dorsoven-
trally oriented (Fig. 4C, D). Indeed, the height of the poste-
rior articular surface is around 1.3 times its maximum
width. The centrum is only gently transversely constricted
at mid-length, with slightly concave lateral surfaces
Downloaded By: [Ezcurra, Martín Daniel] At: 14:41 31 July 2010
376 M. D. Ezcurra
Figure 3. Proximal caudal vertebra of Chromogisaurus novasi in A, D, right lateral; B, E, posterior; and C, F, dorsal views. Abbreviations:
ns, neural spine; paf, posterior articular facet; poz, postzygapophysis; ppl, prezygo-postzygopophyseal lamina; prz, prezygapophysis; tp,
transverse process. Scale bar = 1cm.
(Fig. 4I, J). An incipient longitudinal groove is present
along the posterior third of the ventral surface of the
centrum. Only the bases of the transverse processes are
preserved, arising slightly more posteriorly than mid-length
of the neural arch (Fig. 4K, L). The bases of the trans-
verse processes project laterally. Only the base of the left
prezygapophysis is preserved. It projects anteriorly in side
view and anterolaterally in dorsal view. The postzygapophy-
ses are available, but they are deformed in the transverse
plane. They arise directly below the neural spine, and
no median notch separates one from the other, contrast-
ing with Eoraptor (PVSJ 512), Panphagia (PVSJ 874),
Guaibasaurus (UFRGS PV 0725T) and Saturnalia (MCP
3846-PV). The articular surface of the postzygapophysis
is lateroventrally oriented. It is extended well posteriorly,
surpassing the posterior-most level of the centrum. A well
developed and sharp prezygo-postzygopophyseal lamina is
also present. The neural spine arises anteriorly between the
base of both prezygapophyses, but remains as a very low
and transversely thin lamina up to the level of the postzy-
gapophyses, as in Silesaurus (Dzik 2003), Eoraptor (PVSJ
512) and other basal dinosauriforms. Between both postzy-
gapophysis, the neural spine curves strongly dorsally, reach-
ing a height that exceeds that of the centrum plus the base
of the remaining neural arch. The neural spines of Eoraptor
(PVSJ 512) are proportionally lower than those of Chromo-
gisaurus. The neural spine is more posteriorly extended
than the postzygapophyses, as occurs in other basal
dinosauriforms.
Ulna. A partial proximal end of the right ulna is avail-
able, preserving the complete olecranon processes (Fig. 5;
Table 1). This fragmentary bone was preliminarily inter-
preted as the posterior end of the right jaw (Ezcurra 2008).
The preserved portion of the ulna indicates that the fore-
limb of Chromogisaurus was very stout in relation to
the hindlimb elements, resembling the condition present
in Saturnalia (Langer et al. 2007b) and more derived
sauropodomorphs. The olecranon process is extremely
proximodistally enlarged, in relation to its anteroposterior
depth and the inferred depth of the proximal end of the
bone. This condition is almost identical to that of Satur-
nalia (Langer et al. 2007b), and clearly contrasts with the
less developed olecranon of Herrerasaurus (Sereno 1993),
Eoraptor (PVSJ 512), neotheropods (e.g. Dilophosaurus,
Liliensternus, Coelophysis; UCMP 37302; HMN MB R.
2175; QG 1), Guaibasaurus (Bonaparte et al. 2007) and
basal plateosaurian sauropodomorphs (e.g. Unaysaurus,
Plateosaurus, Adeopapposaurus; Leal et al. 2004; Bonnan
& Senter 2007; Martinez 2009). The posterolateral surface
of the olecranon is formed by a sheet of bone, bearing
strongly marked longitudinal striations (Fig. 5A). Exactly
the same condition is present in Saturnalia, and Langer
et al. (2007b) interpreted this sheet of bone as an inde-
pendent ossification. The latter seems to be also true for
Chromogisaurus. This probable ossification forms a distinct
posteriorly-projected knob, which exceeds the posterior
margin of the ulnar shaft, as is also present in Saturna-
lia (Langer et al. 2007b). Langer et al
. (2007b) pointed
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A new early dinosaur and reassessment of dinosaur origin and phylogeny 377
Figure 4. Mid-caudal vertebra of Chromogisaurus novasi in A, B, right lateral; C, D, posterior; E, F, left lateral; G, H,anterior;I,
J, ventral; and K, L, dorsal views. Abbreviations: ns, neural spine; paf, posterior articular facet; poz, postzygapophysis; ppl, prezygo-
postzygopophyseal lamina; prz, prezygapophysis; tp, transverse process; vg, ventral groove. Scale bar = 1cm.
out that the striated surface of this ossification represents
the insertion of the M. triceps tendon. This ossification is
anteroproximally limited by a vertical sharp edge which
posteriorly bounds a concave and smooth surface, proxi-
moanteriorly oriented. Below this concavity, an anteriorly
projected knob is present, proximally covering the humeral
articulation area. Langer et al. (2007b) interpreted the latter
as a second independent ossification, which defines a prox-
imally hollow olecranon, and the same seems to be the
case for Chromogisaurus. These authors pointed out that
the presence of these ossifications and extremely enlarged
olecranon in two specimens of Saturnalia suggest that it is
not a pathological trait, but typical for the taxon. Its pres-
ence in Chromogisaurus clearly bolsters the claim of these
authors.
The humeral articulation area, for the reception of the
ulnar condyle, is strongly concave, and ventrolaterally
bounded by a conspicuous, but low, ridge. This ridge
extends distally, as a vertical structure, onto the lateral
process (Godefroit et al. 1998) directly below the humeral
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378 M. D. Ezcurra
Figure 5. Proximal end of the right ulna of Chromogisaurus novasi in A, B, posterolateral; and C, D, anterior views. Abbreviations: io1–2,
independent ossification 1 and 2; its, insertion M. triceps scapularis; lp, lateral process; oas, olecranon articular surface; ol, olecranon
process; oss, olecranon striated surface; r, ridge. Scale bar = 5 mm.
articulation. Langer et al. (2007b) pointed out that this
lip-like structure might represent attachment areas for liga-
ments of the elbow joint (Baumel & Raikow 1993; Meers
2003). This vertically oriented ridge seems to represent
the base of the vertical crest which runs longitudinally
across the proximal half of the ulnar shaft. Posteriorly to
the ridge which bounds the posteroventral border of the
humeral articulation area is a concave and slightly striated
surface. This area has been interpreted as the insertion of the
M. triceps scapularis in Saturnalia (Langer et al. 2007b).
The lateral process of Chromogisaurus is less developed
than in Saturnalia (MCP 3845-PV). The anterior process is
not preserved in the available specimen of Chromogisaurus.
The medial surface of the ulna, directly below of the olecra-
non process, is concave, for the reception of the radius. At
the level where the ulnar shaft is broken off, it is elliptical
in cross-section and with an anteroposterior main axis.
Ilium. The available right ilium is well preserved, only
lacking its preacetabular process (Fig. 6; Table 2). The
ilium of Chromogisaurus closely approaches that of
Guaibasaurus (UFRGS PV 0725T), Saturnalia (MCP
3844-PV, 3846-PV), Panphagia (PVSJ 874; Martinez &
Alcober 2009) and Agnosphitys (Fraser et al. 2002), sharing
an incipiently perforated acetabulum and an extremely long
postacetabular process. The posterior end of the postac-
etabular process of Chromogisaurus has a thick and trape-
zoideal rugose area on its lateral surface (Fig. 6A, B), which
tapers anterodorsally, a feature also present in Saturnalia
(MCP 3844-PV; Langer 2003) (Fig. 14A). Langer (2003)
suggested that these muscle scars are the origin areas for
the M. flexor tibialis externus (ventrally) and M. iliotibialis
(anterodorsally, close to the dorsal margin of the iliac blade).
In a paratype specimen of Saturnalia (MCP 3845-PV),
these muscle scars are less developed than in the holotype of
the species (MCP 3844-PV) and Chromogisaurus, but still
exhibit the same shape and position. In other basal dinosaurs
(e.g. Herrerasaurus, Caseosaurus, Panphagia; PVL 2566,
UMMP 8870, Martinez & Alcober 2009), the postacetab-
ular process also present thick rugosities, but their shape
and development are clearly distinct from that of Saturna-
lia and Chromogisaurus (Fig. 17). The posterior end of the
process bears a pointed posteroventral prong and a rounded
posterodorsal margin (Fig. 6A, B, E, F), as in Saturnalia and
some other sauropodomorphs, but this is absent in Panpha-
gia (PVSJ 874) and Guaibasaurus (UFRGS PV 0725T).
The lateral surface of this posteroventral prong presents
a striated surface, which Langer (2003) interpreted as the
origin area of the M. flexor tibialis internus. A well devel-
oped brevis shelf is present, but does not merge anteriorly
with the supraacetabular crest as occurs in Eoraptor (PVSJ
512) and neotheropods (e.g. Dilophosaurus, Carnotau-
rus
; UCMP 37302; MACN-CH-PV 894). The brevis shelf,
together with a prominent posteromedial lamina, delimits
a well developed brevis fossa, which gently flares trans-
versely at its posterior end (Fig. 6G, H). The brevis fossa
corresponds to the origin area of the M. caudofemoralis
brevis (Gatesy 1990). The posteromedial lamina of Chro-
mogisaurus is much less developed than in Panphagia
(Martinez & Alcober 2009).
As is characteristic for dinosaurs (Ezcurra 2006), the iliac
blade of Chromogisaurus is high and presents a straight
dorsal margin in lateral view. In dorsal view, the iliac blade
of Chromogisaurus strongly curves laterally (Fig. 6E, F), as
occurs in other sauropodomorphs, such as Saturnalia (MCP
3846-PV), Guaibasaurus (UFRGS PV 0725T), Panphagia
(PVSJ 874), Riojasaurus (PVL 3808), Efraasia (Galton
1984) and Lessemsaurus (PVL 4822) (Fig. 16). Directly
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A new early dinosaur and reassessment of dinosaur origin and phylogeny 379
Figure 6. Right ilium of Chromogisaurus novasi in A, B, lateral; C, D, medial; E, F, dorsal; and G, H, ventral views. Abbreviations:
aw, acetabular wall; bs, brevis shelf; bf, brevis fossa; cs?, probable insertion of the caudosacral rib; d, depression, origin M. iliofemoralis
cranialis; ip, ischiadic peduncle; omi, origin M. iliotibialis; omfi, origin M. flexor tibialis internus; omfe, origin M. flexor tibialis externus;
plp, posterolateral prong; pms, posteromedial shelf; pp, pubic pedunlce; sac, supraacetabular crest; sr1–2, sacral 1 and 2 rib attachment
areas; t; tuberosity. Scale bar = 2cm.
above the supraacetabular crest, a triangular depression
exists on the iliac blade, probably for the origin of the
M. iliofemoralis cranialis (following Langer 2003). The
base of the preacetabular process is represented by a thick
and well developed buttress, which contacts the supraac-
etabular crest ventrally, resembling other basal dinosauri-
forms (e.g. Herrerasaurus, Silesaurus, Saturnalia, Eorap-
tor; Novas 1993; Dzik 2003; Langer 2003; PVSJ 512). The
supraacetabular crest is conspicuous above the acetabu-
lum and continues as a well laterally developed crest along
the extension of the pubic peduncle. Indeed, the supraac-
etabular crest reaches the distal end of the pubic pedun-
cle, as occurs in Saturnalia (MCP, 3844-PV, 3846-PV),
Guaibasaurus (UFRGS PV 0725T), Panphagia (Martinez
& Alcober 2009, fig. 8) and Eoraptor (PVSJ 512), but
contrasting with Silesaurus (Dzik 2003), ornithischians
(UCMP 129614), Herrerasaurus (PVL 2556; MACN-PV
18060) and neotheropods (UCMP 37302, 77270, 129618;
QG 1). This crest projects directly laterally, contrasting with
basal neotheropods, in which this structure is lateroventrally
deflected, partially overlapping the acetabulum in lateral
view (e.g. Dilophosaurus, Lophostropheus, Coelophysis,
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380 M. D. Ezcurra
Liliensternus; UCMP 37302; Ezcurra & Cuny 2007; QG 1;
MB R. 2175). The supraacetabular crest of Chromogisaurus
is strongly ventrally curved in lateral view, contrasting with
the almost straight crest present in Panphagia (Martinez
& Alcober 2009, fig. 8). Contrasting with Guaibasaurus
(Langer et al. 2007c), no excavation is observed on the
lateral surface of the actetabular wall, just anterior to the
ischiadic peduncle.
The pubic peduncle is very long, resembling Saturna-
lia (MCP 3844-PV), Guaibasaurus (UFRGS PV 0725T),
Panphagia (Martinez & Alcober 2009, fig. 8) and more
derived sauropodomorphs (PVL 3808, 4822; Benton et al.
2000). The acetabulum is only incipiently open, as in
Saturnalia (Langer 2003), Guaibasaurus (Bonaparte et al.
1999, 2007), Panphagia (Martinez & Alcober 2009) and
Agnosphitys (Fraser et al. 2002). Contrasting with the holo-
type of Saturnalia (MCP 3844-PV), the ventral border of
the iliac wall of Chromogisaurus is concave (Fig. 14A,
B). However, different specimens of Guaibasaurus present
a straight (Bonaparte et al. 1999; MCP 2355-PV) or a
concave (UFRGS PV 0725T) ventral margin, showing that
the ventral shape of the acetabular wall is intraspecifically
variable. The ischiadic peduncle is anteroposteriorly broad,
with a mostly ventrally and slightly posteriorly oriented
articular surface for the ischium. The antitrochanter is posi-
tioned on the anteroventral corner of this peduncle.
The medial surface of the iliac blade presents a complex
topography, exhibiting scars for the attachment of the two
primordial sacral ribs and a probable caudosacral vertebra
(Fig. 6C, D). The anteriormost scar, for the first sacral rib,
is positioned at the base of the preacetabular process. The
attachment for the first primordial sacral rib presents a ‘C’
contour in basal saurischians (Langer & Benton 2006, fig.
7), and it seems to be also the case in Chromogisaurus.
The ventral component of the scar for the first sacral rib
is very conspicuous, being longitudinally extended along
the base of the ischiadic and pubic peduncles and reaching
the base of the preacetabular process. The dorsal compo-
nent is very shallow and is situated close to the dorsal
margin of the iliac blade. The shape of the first primordial
sacral rib scar closely approaches the morphology exhibited
by Herrerasaurus (PVL 2556), but clearly contrasts with
the more dorsoventrally reduced and posteriorly restricted
ventral component of Saturnalia (Langer & Benton 2006).
The scar for the second sacral rib originates at the level of
the ischiadic peduncle and extends posteriorly up to three-
quarters of the length of the postacetabular process. This
scar is subrectangular and oblique to the longitudinal axis of
the bone, with its highest point situated at its posterior end.
Contrasting with Herrerasaurus, but resembling Saturnalia
(Langer & Benton 2006), the scar of the second primordial
sacral of Chromogisaurus is formed by a single longitudi-
nal depression, and no well-developed dorsal component is
observed. The ventral border of this scar is delimited by
a well developed posteromedial lamina, which forms the
Figure 7. Probable ischial shaft of Chromogisaurus novasi in A,
medial?; B, cross-section; and C, dorsal? views. Abbreviations:
lr, longitudinal ridge. Scale bar = 1cm.
medial border of the brevis fossa. This shelf-like structure
continues anteriorly onto the medial surface of the ilium
up to directly above the ischiadic peduncle, and it is much
less medially developed than in Panphagia (Martinez &
Alcober 2009). On the other hand, the dorsal border of the
second sacral scar is formed by a medially bulged surface.
This medially inflatened surface occupies a large area on
the iliac blade and is triangular. At the posterior end of
the medial surface of the postacetabular process, a concave
and rounded depression is present. This depression would
represent the scar for the third sacral rib. As occurs in Satur-
nalia (Langer 2003), this third sacral scar would indicate
the adding of a caudal vertebra to the sacral series (i.e. a
caudosacral). The medial surface of the iliac blade, above
the subtriangular inflatened area and the scar for the second
sacral, is almost flat. The medial surface of the acetabular
wall is flat and slightly convex.
Ischium? A fragment of a rod-like bone is here interpreted
as a probable partial ischial shaft (Fig. 7). This purported
portion of ischial shaft is straight and oval in cross-section.
A well developed and sharp longitudinal ridge is present.
This structure may represent the contact area for the other
ischium.
Femur. Remains of both femora are preserved (Figs 8,
9; Table 2). Most of the right femur is available, lacking
its proximal end and distal condyles (Fig. 8). Otherwise,
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A new early dinosaur and reassessment of dinosaur origin and phylogeny 381
Figure 8. Right femur of Chromogisaurus novasi in A, B, lateral; C, D, medial; and E, F, posterior views. Abbreviations: cd, concave
depression; ft, fourth trochanter; imc, insertion of the M. caudofemoralis longus; lf, lateral fossa; pf, plopiteal fossa; pll, posterolateral
intermuscular line. Scale bar = 2cm.
the left femur is represented by the proximal half of the
bone, lacking the proximal end (Fig. 9), and a fragmen-
tary distal end. The femoral shaft of Chromogisaurus is
bowed posteriorly in side view. A well developed and thick
trochanteric shelf is present (Fig. 9A, E) (not preserved
in the right femur), as in several dinosauriforms (e.g.
Chindesaurus, Herrerasaurus, Dilophosaurus, Saturnalia,
Pseudolagosuchus, Silesaurus; PEFO 10395; PVL 2556;
UCMP 37302; MCP 3844-PV; PULR 053; Dzik 2003). By
contrast, in all the available specimens of Guaibasaurus
the trochanteric shelf is absent (Langer & Benton 2006;
MCP 2355-PV; UFRGS PV 0725T; contra Bonaparte et al.
2007). The trochanteric shelf of Chromogisaurus originates
on the anterior surface of the femur and continues along
most of the lateral surface of the bone. The shelf slopes
distally, merging with the femoral shaft, on the postero-
lateral corner of the bone. On the other hand, contrasting
with Chromogisaurus,inSaturnalia the trochanteric shelf
continues on the posterior surface of the femur (MCP 3844-
PV, 3845-PV) (Fig. 14C). The trochanteric shelf presents a
rugose surface, which seems to indicate the insertion of the
M. iliofemoralis externus (Langer 2003).
A very large and deep elliptical fossa is present on
the lateral surface of both femora (Figs 8A, B, 9A, E),
immediately below the trochanteric shelf. This fossa opens
widely anteroposteriorly, whereas distally it ends sharply
and abruptly. The fossa exhibits the same position, size, and
contour in both available femora, and there is no crushing
that would suggest deformation of the medullary cavity. The
surface of this fossa is smooth, thus it seems to not repre-
sent a muscle origin area. Thus, the function of this fossa is
unknown. This feature is unknown in other basal dinosauri-
forms, thus, it seems to represent an autapomorphy of Chro-
mogisaurus. Furthermore, the lateral fossa confers a B-
shaped cross-section at the level of the fourth trochanter
Figure 9. Left femur of Chromogisaurus novasi in A, E, lateral;
B, H, medial; C, G, posterior; and D, H, cross-section views.
Abbreviations: cd, concave depression; ft, fourth trochanter; lf,
lateral fossa; pll, posterolateral intermuscular line; ts, trochanteric
shelf. Scale bar = 1cm.
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382 M. D. Ezcurra
(Fig. 9D, H). The fourth trochanter lies in the proximal
half of the femur and is asymmetric (Fig. 8A–D), as in
non-neotheropod basal saurischians. Distally to the level of
the trochanteric shelf, the posterior surface of the femur
is concave (Figs 8E, F, 9C, G). This concavity is deeper
proximally, and bounded by the posterolateral intermuscu-
lar line and the fourth trochanter. On the medial surface of
the femur, at the anteroventral base of the fourth trochanter,
a fossa bearing strongly marked longitudinal striations is
present. This area corresponds to the insertion of the M.
caudofemoralis longus (Langer 2003).
The distal end of the available femora of Chromogisaurus
is incomplete. However, it can be seen that it is somewhat
transversely expanded and bears a long and deep longitudi-
nal popliteal fossa.
Tibia. The right tibia is completely preserved, but some-
what transversely compressed artificially (Fig. 10; Table 2).
The proximal end is well anteroposteriorly expanded. The
cnemial crest is moderately developed and slightly curved
laterally, as occurs in other basal dinosaurs (Fig. 10C, D).
The posterior condyles of the proximal end of the bone are
asymmetric, with the medial condyle much more posteri-
orly extended than the lateral one. This condition is also
present in sauropodomorphs (Yates 2007a, b; including
Panphagia; PVSJ 874, contra Martinez & Alcober 2009),
Eoraptor (PVSJ 512), ornithischians (UCMP 130580),
Marasuchus (Sereno & Arcucci 1994) and Pseudolago-
suchus (PULR 053). The proximal end of the tibia reaches
its highest point at the cnemial crest (Fig. 10A, B). In
lateral view, the cnemial crest has a rounded profile. The
lateral surface of the cnemial crest is rugose, which could
be the origin area of the M. tibialis cranialis proximally
and M. extensor digitorum longus more distally (sensu
Langer 2003; McGowan 1979; Dilkes 2000). The poste-
rior condyles are strongly projected backwards. They are
distinct from one another, yet are not separated by a median
notch, as occurs in other dinosaurs (e.g. Saturnalia, Panpha-
gia, Chindesaurus; Langer 2003; PVSJ 874; PEFO 10395).
The proximal articular surface of the bone is concave,
due to a proximally inflated medial margin. As occurs in
Saturnalia (Langer 2003; MCP 3844-PV), a wide, but very
low, longitudinal tuberosity bounds posteriorly the lateral
concavity formed by the curved cnemial crest (Fig. 10A,
B). Curiously, this tuberosity is located in the same posi-
tion to that of the fibular crest of basal neotheropods (e.g.
Dilophosaurus, Liliensternus, Segisaurus; UCMP 37302;
MB R. 2175; UCMP 32101) and silesaurids (e.g. Sile-
saurus, Sacisaurus; Dzik 2003; Ferigolo and Langer 2007;
MCN PV10020). This tuberosity participates in attachment
Figure 10. Right tibia of Chromogisaurus novasi in A, B, lateral; C, D, proximal; E, F, distal; G, H, posterior; and I, J, anterior views.
Abbreviations: ad, anterior depression; cn, cnemial crest; fap, facet for the reception of the ascending process of the astragalus; lc,
lateral condyle; ln, lateral notch; lt, lateral tuberosity; mc, medial condyle; plc, posterolateral concavity; plp, posterolateral process; plt,
posterolateral tuberosity; se, sharp edge. Scale bar = 2cm.
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A new early dinosaur and reassessment of dinosaur origin and phylogeny 383
of the Lig. tibiofibularis (Langer 2003). The latter structure
is bounded, anteriorly and posteriorly, by concave surfaces
for the reception of the fibula. On the posterolateral border
of the bone, a low but well laterally inflatened tuberosity is
present (Fig. 10A, B, G, H), directly below the distal level
of the cnemial crest. On the medial side, a large and deep
concave area exists directly below the proximal end of the
tibia.
The tibial shaft is straight along all its extension.
The lateral surface of the shaft is strongly convex, with
a conspicuous and sharp median edge. On the other
hand, the medial surface of the tibial shaft is planar.
Both anterior and posterior borders of the tibial shaft
are convex, but the former is more acute. The distal
articular surface of the tibia of Chromogisaurus closely
resembles that of Saturnalia (MCP 3844-PV), being more
anteroposteriorly deep than transversely wide (Fig. 10E, F).
Nevertheless, the transverse compression of the distal tibia
of Chromogisaurus could be exaggerated by post-mortem
deformation. Otherwise, a paratype specimen of Saturnalia
exhibits a distal end of the tibia transversely wider than it is
anteroposteriorly deep (MCP 3846-PV), contrasting with
the holotype specimen. Accordingly, the proportions of the
distal outline of the tibia seem to depend on intraspecific
variability, at least in Saturnalia tupiniquim. The borders of
the distal end of the tibia of Chromogisaurus are straight,
thus lacking a rounded distal articular surface (Langer
2003, MCP 3844-PV). The latter condition resembles
that of other eusaurischians (e.g. Panphagia, Saturnalia,
Guaibasaurus, Eoraptor, neotheropods, Riojasaurus;
Martinez & Alcober 2009; MCP 3844-PV, 2356-PV; PVSJ
512; PULR 076; PVL 3808), but contrasts with that of more
basal dinosauromorphs (e.g. Dromomeron, Lagerpeton,
Pseudolagosuchus, Silesaurus, Herrerasaurus; GR 220;
PULR 53; Dzik 2003; Novas 1993). A conspicuous lateral
notch starts with the distal end of the bone. This longitudinal
notch opens distally into the anterior articular facet for the
reception of the ascending process of the astragalus. On the
anterior surface, a proximodistally short but deep sulcus is
present. This sulcus does not reach the distal articular end of
the bone. The posterolateral surface of the distal end of the
tibia is concave, resembling the condition present in some
eusaurischians (e.g. Panphagia, Saturnalia, Guaibasaurus,
neotheropods; Martinez & Alcober 2009; MCP 3844-PV,
2356-PV; Ezcurra & Novas 2007b). The posterolateral
process of the distal tibia is moderately developed, as
is the case in Herrerasaurus (Novas 1989), Saturnalia
(MCP 3844-PV), Panphagia (Martinez & Alcober 2009)
and other basal sauropodomorphs (e.g. Riojasaurus;PVL
3808). However, in Chromogisaurus this process is not
as developed as in Eoraptor (PVSJ 512), Guaibasaurus
(MCP 2356-PV), Chindesaurus (Nesbitt et al. 2007) and
neotheropods (Dilophosaurus,
Liliensternus, Segisaurus,
Zupaysaurus; UCMP 37302; MB R. 2175; UCMP 32101;
Ezcurra and Novas 2007b). In anterior view, the articular
facet for the reception of the ascending process of the
astragalus is diagonal to the longitudinal axis of the bone
(Fig. 10I, J). Thus, the articular facet faces laterodistally
and its distal-most region is located at the anteromedial
corner of the distal end. This condition contrasts with that
of basal dinosauriforms, such as Herrerasaurus (Novas
1989; MACN-PV 18060; PVL 2556) and Silesaurus
(Dzik 2003), but resembles that of Guaibasaurus (MCP
2356-PV), Saturnalia (MCP 3844-PV), Eoraptor (PVSJ
512), neotheropods (e.g. Dilophosaurus, Zupaysaurus;
UCMP 77270; Ezcurra and Novas 2007b) and plateosauri-
ans (e.g. Riojasaurus; PVL 3845). The distal articular
surface of the tibia of Chromogisaurus presents a moder-
ately deep posteromedial notch, bounded by convex
surfaces.
Fibula. The right fibula is preserved, with a damaged
proximal end and lacking its distal end (Fig. 11; Table
2). The shaft is straight in side view and its anteroposte-
rior depth decreases gradually towards its distal end (Fig.
11A, B). The fibular shaft is thinner than that of the
tibia at mid-length, as in other basal dinosaurs (e.g. Stau-
rikosaurus Herrerasaurus, Saturnalia, Guaibasaurus and
Eoraptor), but contrasting with the more pronounced differ-
ence present in neotheropods and ornithischians (Langer &
Benton 2006). The proximal end is well anteroposteriorly
expanded but strongly compressed transversely. In cross-
section the proximal fibula is oval, with sharp anterior and
posterior edges. The lateral surface of the proximal end is
slightly convex, but along the shaft the lateral surface of
the bone becomes strongly convex. On the other hand, the
medial surface of the proximal end is planar, but along the
shaft, it bears a deep longitudinal median fossa (Fig. 11C,
D), mostly for contact of the lateral surface of the tibia.
Thus, in cross-section the fibular shaft acquires a semilu-
nate shape. The anterior and posterior borders of the shaft
are rounded. Below the proximal expansion of the fibula,
a low tuberosity is present on the anterolateral edge of
the shaft (Fig. 11A, B, E, F), probably for the insertion
of the M. iliofibularis (Carrano & Hutchinson 2002). This
tuberosity is clearly less developed than in neotheropods
(e.g. Segisaurus, Dilophosaurus; UCMP 32101, 37302).
Metatarsal II. The overall morphology of the metatarsals
resembles that of Silesaurus and other basal dinosaurs,
contrasting with the extremely gracile metatarsus of more
basal ornithodirans (Langer & Benton 2006). The left
metatarsal II is preserved, only lacking its proximal end
(Fig. 12A–I; Table 2). The shaft of the metatarsal II is
slightly bowed medially in dorsal view (Fig. 12A, B). In
cross-section the shaft is circular at mid-length. A distinct
articular facet is present at the most proximal preserved
portion of the bone. This facet is for the reception of the
metatarsal I, and it lies at the posteromedial corner of the
bone (Fig. 12E, F). Thus, the proximal end of the metatarsal
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384 M. D. Ezcurra
Figure 11. Right fibula of Chromogisaurus novasi in A, B, lateral; C, D, medial; and E, F, anterior views. Abbreviations: md, medial
depression; til, iliofibularis muscle insertion. Scale bar = 2cm.
II seems to have overlapped the metatarsal I in dorsal view.
The facet for the reception of the metatarsal I is triangular,
deep and with conspicuous borders.
The distal end of the metatarsal II expands transversely.
At this region, the bone presents well-developed collateral
pits, with the medial one as the largest (Fig. 12C–F). On
the dorsal surface of the distal trochlea, a transversely wide
depression is present, proximally bounded by a conspicu-
ous lip. The lateral distal condyle is more ventrally devel-
oped and transversely thinner than the medial one (Fig.
12G, I), contrasting with the more symmetric condition
present in other basal dinosauriforms (e.g. Eoraptor, Satur-
nalia, Herrerasaurus, Silesaurus, Dilophosaurus;PVSJ
512; Langer 2003; MCP 3844-PV; MACN-PV 18060;
ZPAL Ab III 361/19; UCMP 37302) (Figs 12G, I, 14F). A
distinct ventral notch separates the lateral and medial distal
condyles. The distal end of the metatarsal II of Chromo-
gisaurus also exhibits a strong proximodistal asymmetry,
with the medial condyle more distally projected than the
lateral one.
Metatarsal V. The left metatarsal V is preserved (Fig.
13; Table 2). This metatarsal is more gracile than that
of Plateosaurus (MACN-PV 10052), Adeopapposaurus
(Martinez 2009) and Lessemsaurus (Pol & Powell 2007),
but its overall proportions resemble that of Silesaurus (Dzik
2003), Herrerasaurus (Novas 1993), Saturnalia (Langer
2003), Guaibasaurus (Bonaparte et al. 2007), Panty-
draco (Yates 2003a) and neotheropods (e.g. Dilophosaurus,
Coelophysis; Welles 1984; Colbert 1989). The proximal end
of the bone is gently expanded dorsoventrally, but exhibits
a strong medial expansion. A high and proximodorsally
oriented flange is present in the proximal end, resulting in a
gently concave and oval proximal surface. This flange also
produces a concave surface on the dorsal side of the prox-
imal end of the bone. Otherwise, the ventral surface of the
proximal end is gently convex.
The metatarsal shaft is plate-like, strongly dorsoventrally
compressed. Both dorsal and ventral surfaces are gently
convex. The lateral and medial margins of the metatarsal
are parallel along the shaft. The distal end of the bone
is slightly transversely expanded and lacks a distal articu-
lar facet. The latter feature suggests the complete absence
of the pedal digit V, as also occurs in Saturnalia (Langer
2003).
Pedal phalanges. The complete left pedal digit II, in natu-
ral articulation (Fig. 12J–M; Table 2), and a partial isolated
phalanx are preserved. The proximal ends of the non-ungual
phalanges are much more transversely and dorsoventrally
expanded than the distal end (Fig. 12J–M). At mid-length,
the phalanges present a conspicuous compression. The
first phalanx of the digit II exhibits a well developed
proximodorsal lip, which is directly projected proximally
(Fig. 12H, I). The proximoventral lip is well expanded
transversely. The dorsal surface of the phalanx is convex,
whereas the ventral surface presents a longitudinal concav-
ity. The distal end exhibits a distinct trochlea with well
developed collateral fossae. The dorsal surface of the
trochlea bears a well developed, but shallow, ligament pit.
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A new early dinosaur and reassessment of dinosaur origin and phylogeny 385
Figure 12. Left metatarsal II and complete digit II of Chromogisaurus novasi in A, B, J, K, dorsal; C, D, H, I, lateral; E, F, medial; G, I,
distal; J, K, proximal; and L, M, ventral views. Abbreviations: 1-II, first phalanx of digit II; 2-II, second phalanx of digit II; af, articular
facet; afm, articular facet for metatarsal I; clf, collateral fossa; clg, collateral groove; df, dorsal fossa; dl, dorsal lip; lc, lateral condyle;
mc, medial condyle. Scale bars = 1cm.
The second phalanx of digit II is shorter than its
preceding phalanx. The proximodorsal lip of 2-II contrasts
with that of 1-II in its stouter and proximodorsally
oriented body. The dorsal surface of the phalanx 2-II is
concave, contrasting with the convexity seen in 1-II. The
collateral fossae are larger than that of 1-II. The distal
trochlea and the dorsal ligament pit are similarly devel-
oped to those in 1-II. The pedal ungual of the second
digit is slightly ventrally curved, resembling other basal
dinosaurs (e.g. Herrerasaurus, Guaibasaurus, Saturna-
lia, Dilophosaurus; PVSJ 373; MCP 2356-PV, 3845-PV;
UCMP 37302), but contrasting with the almost straight
pedal ungual of Eoraptor (PVSJ 512). The ungual of the
second digit of Chromogisaurus is longer than its preced-
ing phalanx, contrasting with the condition present in
some basal dinosauriforms (e.g. Eoraptor, Lesothosaurus,
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386 M. D. Ezcurra
Figure 13. Left metatarsal V of Chromogisaurus novasi in A,
dorsal; B, lateral; and C, proximal views. Abbreviations: mp,
medial projection. Scale bar = 1cm.
Herrerasaurus, Dilophosaurus, C. rhodesiensis, Panty-
draco; PVSJ 512; Thulborn 1972; Novas 1993; Welles
1984; QG 1; Yates 2003a). Nevertheless, pedal unguals
of the second digit which exceed the length of the phalanx
2-II are also observed in a wide variety of archosauriforms,
such as Euparkeria (Ewer 1965), Lagerpeton (Sereno
& Arcucci 1993; PULR 06), Heterodontosaurus (Santa
Luca 1980), Guaibasaurus (MCP 2356-PV), Anchisaurus
(Galton 1976) and C. bauri (Colbert 1989). The proxi-
modorsal lip is thick and poorly developed. The ventral
flexor tubercle is incipient. The ventral surface of the claw
is wide and concave, contrasting with the almost planar
condition of Eoraptor (PVSJ 512). The collateral grooves
are well developed; they do not bifurcate proximally but
strongly curve ventrally, distally to the flexor tubercle. The
distal-most tip of the ungual is not preserved.
Discussion
Chromogisaurus novasi as a new species
of early dinosaur
As mentioned in the diagnosis, the available remains of
Chromogisaurus novasi exhibit several features allowing
its distinction from all other known dinosauromorphs. The
autapomorphic features of Chromogisaurus are discussed
below:
1. Femoral lateral surface with well developed fossa
immediately below the trochanteric shelf (Figs 8A,
B, 9A, E, 14D). In Chromogisaurus a deep, large and
triangular fossa is present on the lateral surface of the
femur, directly below the trochanteric shelf. However,
contrasting with Chromogisaurus, in other basal
dinosauriforms the femoral lateral surface presents
gently convex surfaces (e.g. Silesaurus, Eoraptor,
Herrerasaurus, Staurikosaurus, Chindesaurus, Satur-
nalia, Guaibasaurus, P. engelhardti, Riojasaurus,
Lessemsaurus; Dilophosaurus, Liliensternus, Coelo-
physis sp.; Dzik 2003; PVSJ 512; Novas 1993;
Colbert 1970; PEFO 10395; Langer 2003; UFRGS
PV 0725T; MCP 2355-PV; Moser 2003; PVL 3808;
PVL 4822; UCMP 37302, 77270; MB R. 2175;
UCMP 129618). In particular, Saturnalia (MCP
3844-PV, 3846-PV) and other basal dinosaurs (e.g.
Herrerasaurus; PVL 2566) exhibit a posterolateral
fossa which lies between the fourth trochanter and the
femoral posterolateral intermuscular line of Langer
(2003). However, the latter feature is also present in
Chromogisaurus, and it is clearly independent from
the autapomorphic lateral fossa. Indeed, both traits
are separated by the posterolateral intermuscular line
in Chromogisaurus (Fig. 14C, D).
2. Metatarsal II with strongly dorsoventrally asymmetric
distal condyles (Figs 12, 14). In basal dinosaurs (e.g.
Saturnalia, Herrerasaurus, Dilophosaurus;MCP
3844-PV; MACN-PV 18060; UCMP 37302), the
distal condyles of the metatarsal II are separated
from one another by a deep and wide ventral groove,
and the condyles are asymmetric in both proxi-
modistal and dorsoventral axes. On the other hand,
in non-dinosaurian archosaurs (e.g. Effigia, Sile-
saurus, Eucoelophysis, Marasuchus; Nesbitt 2007;
Dzik 2003; Sullivan & Lucas 1999; PVL 3036)
the distal condyles of the metatarsal II are almost
symmetric in dorsal view. The dinosaur condition is
present in Chromogisaurus, but the medial condyle
is further ventrally developed and transversely thin-
ner than in other basal dinosaurs (e.g. Saturnalia,
Herrerasaurus, P. gracilis, Glacialisaurus, Lilien-
sternus
, Dilophosaurus; MCP 3844-PV; MACN-PV
18060; MACN-PV 10082; Smith & Pol 2007; MB R.
2175; UCMP 37302).
The above set of autapomorphies allows the diagnosis
of Chromogisaurus novasi among basal Dinosauriformes.
Furthermore, although the morphology of Chromogisaurus
and Saturnalia are very similar, the Argentinean taxon can
be further distinguished from Saturnalia by the absence
of a deep median notch separating the postzygapophyses
in the proximal and mid-caudal vertebrae, the presence
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A new early dinosaur and reassessment of dinosaur origin and phylogeny 387
Figure 14. Comparison between selected features of B, D, F, Chromogisaurus novasi;andA, C, E, Saturnalia tupiniquim. A, B, right ilia
in lateral views; C, D, left femora in lateral views; and E, F, metatarsals II in distal views. (B, D, F, PVSJ 845; A, C, E, MCP 3844-PV)
(E, reversed right metatarsal). Abbreviations: at, anterior trochanter; aw, acetabular wall; fh, femoral head; ft, fourth trochanter; lc, lateral
distal condyle; lf, lateral fossa; pli, posterolateral intermuscular line; plp, posterolateral prong; pr, posterior rugosity for muscle origin;
sac, supraacetabular crest; ts, trochanteric shelf. Not to scale.
of an ilium with a lesser laterally projected supraacetab-
ular crest, an iliac acetabular wall with concave ventral
margin, well dorsoventrally extended articulation for the
first primordial sacral rib, and a femoral trochanteric shelf
which does not reach the posterolateral corner of the shaft
(Fig. 14C, D). In addition, Chromogisaurus differs from
Panphagia, both taxa coming from the same locality of the
Ischigualasto Fm., in the presence of mid-caudal vertebrae
with postzygapophyses not separated by a median notch, an
ilium with an almost straight supraacetabular crest, postac-
etabular process with a pointed posteroventral corner and
a rounded posterodorsal margin, a strong and anterodor-
sally tapering trapezoidal rugosity for the origin of the Mm.
flexor tibialis and iliotibialis, and the absence of a strongly
medially developed posteromedial lamina on the postac-
etabular process, and tibia with a median notch separating
the medial and lateral proximal condyles. In this regard, all
this evidence supports the assignment of PVSJ 845 to a new
species of early dinosaur.
Phylogenetic analysis
Methods. A cladistic analysis was performed in order to
assess the phylogenetic relationships of Chromogisaurus
novasi (PVSJ 845). The data matrix was based on a
modified version of that first published by Yates (2007a,
b), and modified by Smith & Pol (2007). Three opera-
tional taxonomic units (Chromogisaurus novasi, Panpha-
gia protos and MACN-PV 18649a, the latter specimen
belongs to a dinosaur specimen from the Ischigualasto
Fm. which will be formally described elsewhere; Ezcurra
& Novas 2007a, 2008, in prep.) and 15 characters were
added. The scorings for Chindesaurus, Crurotarsi, Eorap-
tor, Guaibasaurus, Herrerasaurus, Neotheropoda, Orithis-
chia and Saturnalia were reviewed based on first-hand anal-
ysis of specimens, and several modifications have been
made (see Appendix 2 for a full description of them). Only
the holotype specimen of Agnosphitys (ilium) was consid-
ered in the analysis, because the assignment of the referred
specimens to that taxon is not conclusive and it may repre-
sent a quimera (Langer 2004; Bonaparte et al. 2007). The
resulting data matrix is composed of 378 characters and
50 taxa. The non-archosaurian archosauriform Euparkeria
was used to root the recovered most parsimonious trees
(MPTs).
The data matrix was analysed under equally-weighted
parsimony using TNT 1.1 (Goloboff et al. 2008). A heuris-
tic search of 50 replications of Wagner trees (with random
addition sequence) followed by TBR branch swapping
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388 M. D. Ezcurra
Figure 15. Phylogenetic relationships of Chromogisaurus novasi and other basal dinosaurs. A, strict consensus tree depicting the phylo-
genetic position of Chromogisaurus novasi and MACN-PV 18649a; and B, reduced strict consensus (after the exclusion of Agnosphitys)
showing bootstrap (right, greater than 50%) and decay indexes (left). Abbreviations: Dino, Dinosauria; Guaiba, Guaibasauridae; Herr,
Herrerasauridae; Plat, Plateosaurus; Satur, Saturnaliinae; Saur, Saurischia; Saurop, Sauropodomorpha; Ther, Theropoda.
algorithm (holding 10 trees per replicate) was performed.
The best trees obtained at the end of the replicates were
subjected to a final round of TBR branch swapping. Zero
length branches among any of the recovered MPTs were
collapsed (rule 1 of Coddington & Scharff 1994). Multi-
state characters were treated as unordered.
Results. The tree search resulted in 100 MPTs of 1186
steps, with CI = 0.372 and RI = 0.697, and the best score
hit 50 times out of the 50 replications. The obtained MPTs
consistently place Chromogisaurus within Sauropodomor-
pha (Fig. 15), due to the presence of proximal caudal verte-
brae with the base of the neural spine longer than half the
length of the neural arch, iliac blade strongly curved later-
ally, length of the iliac pubic peduncle greater than twice
the anteroposterior depth of its distal end, and proximal
lateral condyle of the tibia more anteriorly placed than the
medial one (Figs 16, 17). Within Sauropodomorpha, Chro-
mogisaurus was found as a member of an early branch
of basal forms, which includes Chromogisaurus, Saturna-
lia, Panphagia, Guaibasaurus and Agnosphitys. This group
is referred here as the family Guaibasauridae, represent-
ing the sister-group of all remaining sauropodomorphs.
The family Guaibasauridae was originally coined by Bona-
parte et al. (1999) as a monospecific entity in order
to include Guaibasaurus candelariensis. Although this
family was diagnosed by a set of characters, no formal
definition is available. Accordingly, Guaibasauridae is
defined here as all archosaurs more closely related to
Guaibasaurus candelariensis than to Carnotaurus sastrei
or Saltasaurus loricatus (see Systematic Palaeontology).
Within Guaibasauridae, a polytomy was obtained among
Agnosphitys, Panphagia, Guaibasaurus and the Satur-
nalia + Chromogisaurus clade. Thus, Chromogisaurus
was unequivocally depicted as more closely related to
Saturnalia than to any other basal saurischian, and both
are enclosed in the new subfamily Saturnaliinae. Due
to its biostratigraphical importance (as a probable spec-
ifier of the Hyperodapedon-Acme Zone) and its well
supported monophyly (see below) (Fig. 15B), the clade
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A new early dinosaur and reassessment of dinosaur origin and phylogeny 389
Figure 16. Ilia of several saurischians in dorsal view. A, Herrerasaurus ischigualastensis (PVL 2566); B, Liliensternus liliensterni (MB
R. 2175); C, Chromogisaurus novasi (PVSJ 845); D, Saturnalia tupiniquim (MCP 3844-PV); E, Guaibasaurus candelariensis (UFRGS
PV 0725T); and F, Riojasaurus incertus (PVL 3808). Abbreviations: 372, curvature of iliac blade in dorsal view; fsr, first sacral rib; sac,
supraacetabular crest; pms, posteromedial shelf; plp, posterolateral prong; pr, posterior rugosities. Not to scale.
Saturnaliinae has been coined here. This clade includes
Saturnalia tupiniquim, Chromogisaurus novasi, and all the
descendants from their most common ancestor (see System-
atic Palaeontology).
The monophyly of Guaibasauridae is supported by the
following unambiguous synapomorphies common to all
the recovered MPTs: (1) ilium with an incipiently open
acetabular wall; (2) iliac postacetabular process longer
than the distance between the pubic and ischial peduncles
(Fig. 17); (3) femur with the proximal tip of the anterior
trochanter at level with the femoral head; (4) distal end of
the tibia with a concave posterolateral corner; and probably
(5) scapula with posterior margin of the acromion process
which rises from the blade at an angle greater than 65
◦
from
the long axis of the bone at its steepest point (unknown
in Guaibasaurus, Agnosphitys and Chromogisaurus); (6)
presence of a caudosacral vertebrae (unknown in Agnosphi-
tys and Panphagia); and (7) pubic shaft almost perpen-
dicular to the longitudinal axis of the ilium (unknown in
Agnosphitys, Chromogisaurus and Panphagia). Further-
more, Chromogisaurus and Saturnalia are nested within
Saturnaliinae by an ulna with an extremely enlarged olecra-
non process with a strongly striated posterolateral surface,
iliac postacetabular process with a pointed posteroventral
corner and a rounded posterodorsal margin, and a strong and
anterodorsally tapering trapezoidal rugosity for the origin
of the Mm. flexor tibialis and iliotibialis (Langer 2003) (Fig.
14A, B), and probably proximal caudal transverse processes
anteriorly bowed.
Beyond the phylogenetic position of Chromogisaurus,
the phylogenetic analysis performed here provides novel
hypotheses regarding basal dinosaur phylogeny. Previous
authors found Agnosphitys and Guaibasaurus to be basal
theropods (Langer 2004; Langer & Benton 2006; Yates
2007a, b), but they are interpreted here as guaibasaurid
sauropodomorphs. Yates (2007a, b) found Agnosphitys to
be a basal theropod based on cranial apomorphies, but
this taxon is restricted here to its holotype (i.e. an isolated
ilium; Fraser et al. 2002). Accordingly, the present analysis
found Agnosphitys as a guaibasaurid sauropodomorph due
to the presence of an ilium with an incipiently open acetab-
ular wall and strongly elongated postacetabular process. A
constraint of the monophyly of the clades obtained in one of
the MPTs was enforced but leaving Agnosphitys as a pivotal
taxon. The search of suboptimal trees under this enforced
constraint showed that three additional steps are required
to obtain Agnosphitys as a non-dinosaurian dinosauriform,
four for a non-eusaurischian position, and five to recover it
as a basal theropod.
Guaibasaurus candelariensis is currently known from
three partial skeletons from the Norian of Brazil (Bona-
parte et al. 1999, 2007), but cranial and cervical elements
remain unknown. Guaibasaurus has been included in previ-
ous cladistic analyses, depicting it as a basal theropod
(Langer 2004; Langer & Benton 2006; Yates 2007a, b)
or a non-eusaurischian saurischian (Langer et al. 2007c).
However, in the present analysis Guaibasaurus has been
found as a member of Sauropodomorpha for the first time.
Guaibasaurus shares with sauropodomorphs, but not with
theropods, the presence of proximal caudal vertebrae with
the base of the neural spine longer than half the length of
the neural arch, ilium with strongly laterally curved blade
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390 M. D. Ezcurra
Figure 17. Iliac character-states among basal saurischians. A, Caseosaurus crosbyensis ( = Chindesaurus?) (UMMP 8870); B,
Guaibasaurus candelariensis (UFRGS PV 0725T); C, Chromogisaurus novasi (PVSJ 845); and D, Saturnalia tupiniquim (MCP 3444-
PV). Abbreviations: 251, medial wall of acetabulum; 252, length of the pubic peduncle; 255, length of the postacetabular process; 258,
shape of the posterior margin of the postacetabular process; 362, muscle origin areas (Mm. flexor tibialis and iliotibialis) on the posterior
portion of the postacetabular process. Not to scale.
(Fig. 16), an elongated pubic peduncle (Fig. 17), and an
ischial shaft with triangular transverse section. Further-
more, Guaibasaurus is included within Guaibasauridae due
to the presence of the synapomorphies listed above. Bona-
parte et al. (2007) suggested that Saturnalia, Guaibasaurus
and Agnosphitys conform a natural group (Guaibasauri-
dae), based on a very similar iliac morphology. The latter
hypothesis is supported here for the first time in a quanti-
tative analysis. It must be pointed out that Guaibasaurus
exhibits some intriguing neotheropod-like features, such
as the presence of a distal tibia with strongly externally
projected posterolateral process (MCP 2355-PV). Never-
theless, the latter condition is also found in other basal
saurischians, including Chindesaurus (Nesbitt et al. 2007)
and Eoraptor (PVSJ 512). Thus, the distribution of this
character is not currently clear within Saurischia. Subopti-
mal trees, under an enforced constraint topology, required
two additional steps to recover Guaibasaurus as a basal
theropod.
Panphagia protos is an early dinosaur recently described
by Martinez & Alcober (2009) from the lower third of
the Ischigualasto Fm. (Valle Pintado locality, late Carnian).
The phylogenetic analysis performed by Martinez &
Alcober (2009), based on the data matrix of Langer &
Benton (2006), recovered Panphagia as the most basal
known sauropodomorph, being the sister-taxon of Satur-
nalia and more derived sauropodomorphs. As mentioned
above, Panphagia was also found here to be a member of
Sauropodomorpha; but within this clade, Panphagia was
recovered as a non-saturnaliin guaibasaurid, and not as the
most basal sauropodomorph. The inclusion of Panphagia in
Sauropodomorpha is supported here by the following char-
acters: (1) supraoccipital wider than high; (2) length of the
cervical centra 3–5 is 2.5–4 times the height of their ante-
rior faces; (3) cervical neural arches 4–8 without postzy-
godiapophyseal lamina; (4) cervical neural arches 4–8 with
weakly developed laminae; (5) ilium with strongly laterally
curved blade; (6) length of the iliac pubic peduncle greater
than twice the anteroposterior depth of its distal end; and (7)
proximal lateral condyle of the tibia more anteriorly placed
than the medial one. Furthermore, the following charac-
ters support the membership of Panphagia in Guaibasauri-
dae: (1) scapula with posterior margin of the acromion
process which rises from the blade at an angle greater than
65
◦
from the long axis of the bone at its steepest point
(unknown in Guaibasaurus, Agnosphitys and Chromo-
gisaurus); (2) iliac acetabular wall incipiently open; (3) iliac
postacetabular process longer than the distance between the
pubic and ischial peduncles; and (4) tibial posterolateral
corner concave (unknown in Agnosphitys). Panphagia is
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A new early dinosaur and reassessment of dinosaur origin and phylogeny 391
more basal than Chromogisaurus and Saturnalia within
Guaibasauridae due to the absence of the synapomorphies
listed above for Saturnaliinae. The recovery of subopti-
mal trees under an enforced constraint topology showed
that four additional steps were required to obtain Panpha-
gia as the most basal sauropodomorph (cf. Martinez &
Alcober 2009), and three additional steps to place it as
a sauropodomorph more derived than guaibasaurids. Two
additional steps were necessary to recover Panphagia as the
sister-taxon of Chromogisaurus.
Martinez & Alcober (2009) justified the position of
Panphagia as less derived than Saturnalia and other
sauropodomorphs based on three characters: (1) distally
recurved crowns; (2) roughly semicircular distal outline
of ischium; and (3) proximal lateral condyle of tibia
posteriorly located. However, the following comments are
warranted:
1. Distally recurved crowns are also found in the most
anterior teeth of the dentary of Saturnalia (MACP
3845-PV) and Pantydraco (Yates 2003a, fig. 8B;
evident in the second crown). Thus this trait is
not only restricted to Panphagia within very basal
sauropodomorphs.
2. Ischia with semicircular distal outline are also present
in Staurikosaurus and Eoraptor (Langer & Benton
2006). The latter two taxa were found within succes-
sive sister-taxa of Sauropodomorpha in the present
phylogenetic analysis, thus the distribution of this
pelvic character is ambiguous within Eusaurischia.
3. A review of the type material of Panphagia shows
that this taxon presents a lateral condyle more anteri-
orly positioned than the medial one (PVSJ 874), and
not equally posteriorly projected as it was originally
described by Martinez & Alcober (2009). Accord-
ingly, Panphagia exhibits the apomorphic state of this
character, as it occurs in Saturnalia, Chromogisaurus
and more derived sauropodomorphs.
The position of Herrerasauria as the most basal saurischi-
ans (Yates 2003a, 2007a, b; Langer 2004; Langer & Benton
2006; Ezcurra 2006; Irmis et al. 2007) is favoured here.
MACN-PV 18649a (Ezcurra & Novas 2007a, 2008) was
found to be a member of Herrerasauria. It is represented by
a partial small forelimb collected from the Ischigualasto
Fm, sharing with Herrerasaurus a manual phalanx 1-I
longer than metacarpal I, strongly curved manual unguals,
and metacarpals IV–V ventral to the others. The new
herrerasaurian specimen exhibits the following autapo-
morphies: (1) phalanx 1-II with conspicuous longitudinal
ridge on its proximolateral border; and (2) manual unguals
with a posteriorly bifurcated lateral groove. Furthermore,
this specimen differs from Herrerasaurus in the presence
of metacarpal I with strongly proximodistally asymmet-
ric condyles, ulnar articular surface subequal to ulnar
distal articular end, radial tapering medially, well devel-
oped proximodorsal lip of phalanx 1-I, and metacarpal
V proportionally longer. These features show that this
specimen belongs to a distinct species of early dinosaur
from that previously described for the Ischigualasto Fm,
which will be described elsewhere (Ezcurra & Novas in
prep.).
Chindesaurus, a fragmentary dinosauriform from the
Norian of USA (Long & Murry 1995), was originally
interpreted as a close relative of Herrerasaurus (Long &
Murry 1995), an assignment subsequently followed by
Novas (1997). Nevertheless, more recent numerical anal-
yses alternatively recovered Chindesaurus as a basal thero-
pod (Yates 2007a, b), a herrerasaurian (Irmis et al. 2007)
or a herrerasaurid (Nesbitt et al.
2009). Otherwise, Nesbitt
et al. (2007) claimed that Chindesaurus cannot be assigned
beyond Saurischia indet. In the present analysis, several
scorings for Chindesaurus have been modified from the
original data matrix of Yates (2007b), some of them previ-
ously supporting its theropodan affinities (see Appendix 2).
Character states which supported the theropod affinities of
Chindesaurus, and were modified here, have been changed
as follows: (1) femur without rounded fourth trochanter in
profile (PEFO 10395; GR 226); (2) unknown presence of
pubic tubercle on the lateral surface of the proximal end
of the bone; and (3) medial peg of calcaneum fitting into
astragalus (Nesbitt et al. 2007).
In the phylogenetic analysis performed here, Chinde-
saurus is found to be either a basal theropod or a non-
eusaurischian saurischian, thus the strict consensus tree
depicts the taxon within a trichotomy composed of Chin-
desaurus, Sauropodomorpha and Theropoda (Fig. 15).
Chindesaurus shares with other saurischians the follow-
ing apomorphies: (1) presence of hyposphene in dorsal
vertebrae; (2) proximal tip of femoral anterior trochanter
distal to the femoral head; (3) a sharp medial margin
around the depression posterior to the ascending process
of the astragalus. Within Saurischia, Chindesaurus would
be more derived than herrerasaurids by the presence of an
ilium with square-ended posterior margin of the postac-
etabular process, but this assignment is weak (Fig. 15B).
Some of the recovered MPTs found Chindesaurus outside
Eusaurischia, as its sister-taxon, due to the absence of a
brevis fossa on the postacetabular process of the ilium.
Furthermore, Chindesaurus is excluded from Theropoda
in some of the MPTs due to the absence of a dorsosacral
vertebra, an anterior end of brevis shelf not connected to
the supraacetabular crest, and supraacetabular crest not
flaring lateroventrally. Accordingly, in the present analy-
sis neither the herrerasaurian or theropodan affinities of
Chindesaurus are consistently favoured. In this regard, the
recovery of suboptimal trees under an enforced constraint
topology showed that only one additional step is required
to obtain Chindesaurus as a herrerasaurian or a basal
sauropodomorph.
Downloaded By: [Ezcurra, Martín Daniel] At: 14:41 31 July 2010
392 M. D. Ezcurra
Eoraptor lunensis was originally interpreted as the most
basal known theropod (Sereno et al. 1993), but recent
phylogenetic analyses have found this early dinosaur to be a
non-eusaurischian saurischian (e.g. Langer 2004; Langer &
Benton 2006; Yates 2007a, b). Numerous character-states
for Eoraptor have been modified here from the original
data set of Yates (2007b), and several of them previously
supported the non-eusaurischian affinities of the taxon.
Among these modified characters are the absence of a broad
suture between the premaxilla and the nasal, the length of
the radius less than the 80% of the humerus, the presence of
a distal expansion in the ischium, and the presence of a distal
tibial articular surface with the lateral side narrower than
the medial side. After these modifications and the new char-
acters added here, the present phylogenetic analysis consis-
tently placed Eoraptor as the sister-taxon of Neotheropoda,
supporting the hypothesis of Ezcurra (2006). Several
apomorphies are shared between Eoraptor (PVSJ 512)
and basal neotheropods (e.g. Dilophosaurus, Zupaysaurus,
Liliensternus, Coelophysis; UCMP 37302, 37303, 77270,
129618; PULR 076; MB R. 2175; QG 1) (Fig. 18), such
as the presence of a subnarial gap, maxilla with a dorsally
upturned anterior end of the alveolar margin, an alveolar
ridge, a subquadrangular anterior border of the maxillary
antorbital fossa, lacrimal ventral ramus with lateral lamina
interrupting the antorbital fossa only near its proximal end
and ventrally restricted to its posterior margin, a dorsal
added to the sacral series, and iliac brevis shelf connected
with the supraacetabular crest. Indeed, several cranial char-
acters previously claimed as coelophysoid synapomorphies
(Rowe & Gauthier 1990; Rauhut 2003; Carrano et al.
2005; Tykoski 2005; Ezcurra and Cuny 2007; Ezcurra
and Novas 2007b) are present in Eoraptor, and therefore
re-interpreted as putative synapomorphies of Theropoda.
Suboptimal trees, under enforced topology, show that four
additional steps are required to obtain Eoraptor as a non-
eusaurischian saurischian or a basal sauropodomorph.
Bootstrapping and Bremer suppor t. In order to test
the robustness of the obtained MPTs, both bootstrap and
Bremer support were performed (Fig. 15B). This anal-
ysis was carried out after the exclusion of Agnosphitys
from the data matrix. Due to the fragmentary nature of
Agnosphitys, several potential guaibasaurid apomorphies
will be treated as ambiguous characters, resulting in a lower
support for the clade. The bootstrap analysis was carried out
with 10 000 replications. Bootstrap support is weak (lower
than 50%) throughout much of the tree, including that of
Guaibasauridae, but some high values are also present. The
clade Dinosauriformes is supported by a bootstrap value of
99%, and the Silesaurus + Dinosauria clade is supported
by 94%. Dinosauria presents a bootstrap frequency of 66%,
and Saurischia a value of 51%. Within Dinosauria, the high-
est recorded bootstrap value is that of Saturnaliinae (85%).
The monophyly of sauropodomorphs more derived than
guaibasaurids and that of sauropodomorphs more derived
than Thecodontosaurus are supported by bootstrap values
of 68% and 75%, respectively.
Bremer support values are shown in Fig. 15B. Decay
indexes are very low (i.e. 1) in only a couple of nodes,
namely Herrerasauridae and Chindesaurus + Eusaurischia.
The decay index of the latter clade is low due to the
pivotal position of Chindesaurus. Within basal Dinosauri-
formes, several nodes are well supported, with a decay
index of 4. Among these clades are Dinosauria, Saurischia,
Sauropodomorpha and sauropodomorphs more derived
than gauibasaurids. Guaibasauridae and Saturnaliinae
present an intermediate decay index (2). Accordingly, the
monophyly of Dinosauria and Saurischia are both quite well
supported by bootstrap and Bremer support in the present
numerical analysis.
Implications in the Late Triassic
biostratigraphy
The close affinities between Chromogisaurus and Satur-
nalia are biostratigraphically relevant. The common pres-
ence of saturnalliins in the lower levels of the Ischigualasto
Fm. and the Brazilian Santa Maria Fm. allow reinforcing
previous biostratigraphical correlations between the Hyper-
odapedon-Acme Zones (late Carnian) of these sedimentary
units (Langer 2005b; Langer et al. 2007a).
Implications in the rise of dinosaurs
The new dinosaur remains reported here help to modify
our understanding of the earliest dinosaur faunas. Chro-
mogisaurus, the new herrerasaurian specimen (MACN-
PV 18649a) and Panphagia protos (Martinez & Alcober
2009) drastically increase the dinosaur alpha-diversity of
the lower levels of the Ischigualasto Fm., as well as the
Carnian global record of the group. Accordingly, they
demonstrate that the diversity of early dinosaurs was not
as restricted as previously thought. In fact, the number
of dinosaur species recognized in the lower levels of the
Ischigualasto Fm. approaches that of the most diverse
tetrapod groups documented in this assemblage, namely
crurotarsans and cynodonts (Table 3). Otherwise, although
predatory dinosaurs were abundant, dinosaurs as a whole
represent around 6% of the total tetrapod sample of the
Ischigualasto Fm. (Rogers et al. 1993). This stratigraph-
ical unit shows that although dinosaurs were a numeri-
cally minor component of the Carnian terrestrial ecosys-
tems (Benton 1988; Rogers et al. 1993), they were already
quite diverse in this early stage of their evolution.
Previous studies have suggested that Carnian dinosaur
diversity was very low (Bonaparte 1982; Charig 1984;
Benton 1988, 2004, 2006; Rogers et al. 1993) in compar-
ison with that of Norian dinosaur-bearing assemblages,
and a steady diversity increase has been described from
the Carnian to the Early Jurassic (Brusatte et al. 2008a).
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A new early dinosaur and reassessment of dinosaur origin and phylogeny 393
Figure 18. Cranial character-states among basal saurischians. A, Herrerasaurus (PVSJ 407); B, Eoraptor (PVSJ 512); and C, Zupaysaurus
(PULR 076). Abbreviations: 38, shape of the lacrimal; 46, shape of the orbit; 364, subnarial gap; 365, alveolar margin of anterior-most
maxilla; 366, anterior margin of maxillary antorbital fossa; 367, dorsoventrally compressed ridge on lateral surface of maxilla (alveolar
ridge); 368, exposition of the lacrimal antorbital fossa in lateral view. Not to scale.
Downloaded By: [Ezcurra, Martín Daniel] At: 14:41 31 July 2010
394 M. D. Ezcurra
Table 3. Diversity of Late Triassic tetrapod species. Tetrapod sample of the lower Ischigualasto Fm. compared to those of Norian
assemblages (lower Caturrita Fm., Petrified Forest Member of the Chinle Fm., upper Los Colorados Fm., and Lower Elliot Fm.).
Abbreviations: Dino, Dinosauria (non-dinosaurian dinosauromorphs between brackets); Prot, Proterochampsidae; Ch, Chelonia; Cru,
Crurotarsi; Sph, Sphenodontia; Proc, Procolophonidae; Dic, Dicynodontia; Cyn, Cynodontia.
Dino Tem Prot Ch Cru Sph Rhy Proc Dic Cyn
Ischigualasto Fm. 5 (0) 2 1 0 4 0 2 0 1 5
Caturrita Fm. 2 (1) 0 0 0 1 1 1 1 1 6
Chinle Fm. 3 (2) 1 0 0 10 0 0 1 0 0
Los Colorados Fm. 4 (0) 0 0 1 5 0 0 0 0 1
Lower Elliot Fm. 6 (0) 1 0 0 1 0 0 0 0 2
However, the worldwide dinosaur Carnian record has been
traditionally compared with the whole Norian record.
This results in underestimation of Carnian relative to
Norian dinosaur diversity, because Carnian dinosaur-
bearing assemblages are mostly restricted to three areas,
corresponding to beds of the Ischigualasto (Argentina),
Santa Maria (Brazil), and Lower Maleri (India) forma-
tions (Langer 2004, 2005a). In sharp contrast, rich
Norian dinosaur-bearing assemblages are numerous and
widely distributed globally, including the Los Colorados
(Argentina; Bonaparte 1972), Laguna Colorada (Argentina;
Casamiquela 1980), Caturrita (Brazil; Langer 2005b),
Lower Elliot (South Africa, Kitching & Raath 1984; Yates
& Kitching 2003; Butler et al. 2007) and Lower Dharmaram
formations (India; Novas et al. 2006; Kutty et al. 2007), and
several Norian depocenters of western Europe (Galton &
Upchurch 2004; Rauhut & Hungerb
¨
uhler 2000) and USA
(Long & Murry 1995; Lucas et al. 1998; Irmis 2005; Irmis
et al. 2007; Nesbitt & Chatterjee 2008). Nevertheless, if
the early dinosaur alpha diversity of the lower Ischigualasto
Fm. is compared with each of these Norian assemblages,
Carnian dinosaur diversity closely resembles that of Norian
times (Table 3).
On the other hand, contrasting with Carnian beds,
dinosaurs were more numerically abundant in Norian
assemblages (Bonaparte 1982). Indeed, dinosaurs repre-
sent between 25% and 60% of the total number of
terrestrial tetrapods in Norian assemblages (Benton 1983,
1994). Accordingly, although dinosaurs increased numer-
ically during the Norian, they did not experience a major
alpha diversification after the Carnian–Norian boundary
(Fig. 19). Therefore, increase in dinosaur diversity and their
numerical dominance over other terrestrial tetrapods were
diachronous processes. Thus, Norian dinosaur dominance
(e.g. Casamiquela 1980; Benton 1983, 1994; Kitching &
Raath 1984; Sander 1992) was preceded by a period of low
abundance but high diversity during the late Carnian. In
this context, the first recorded major step in the early radi-
ation of dinosaurs (i.e. diversification) occurred during the
Carnian.
The Carnian increase of dinosaur diversity did not occur
in an empty ecospace. Indeed, Carnian tetrapod terres-
trial communities were dominated by herbivorous rhyn-
chosaurs and cynodonts, whereas carnivorous crurotarsans
and cynodonts were also common and diverse faunal
components (Azevedo et al. 1990; Rogers et al. 1993).
A high Carnian diversity but relatively poor abundance
of dinosaurs may reflect competitive pressure by non-
dinosaurian tetrapods (Novas 1997). Alternatively, Brusatte
et al. (2008a, b) demonstrated that Carnian and Norian
Figure 19. Diversity of major terrestrial tetrapods during the Carnian–Norian time span in South America. Samples correspond to
the Ischigualasto (lower-third), Caturrita (lower levels) and Los Colorados (La Esquina Fauna) formations. Abbreviations: Ch, Chelo-
nia; Di, Dicynodontia; Pr, Proterochampsidae; Rhy, Rhynchosauria; Tem, Temnospondyli. For detailed explanations see supplementary
material 4.
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A new early dinosaur and reassessment of dinosaur origin and phylogeny 395
temporal trends do not show a coupled increase in dinosaur
evolutionary rates and decrease in crurotarsan rates. The
near extinction of crurotarsans at the Triassic–Jurassic
boundary was not followed by a subsequent radiation of
dinosaurs, as might be expected under competitive models
(Brusatte et al. 2008a). Although the numerical increase of
dinosaurs may be linked with the end-Carnian extinction
event (Benton 1993, 2006; Brusatte et al. 2008a, b), there
is not enough evidence to link this process with a hazardous
historical contingency or a competitive model.
In summary, in contrast with previous hypotheses, the
South American record suggests that the early radiation
of dinosaurs did not occur as a single process during
the Triassic but, at least in two distinct stages: firstly,
lineage diversification, but with low abundance, during the
late Carnian; and secondly, increase in abundance during
the Norian. These processes acting together established the
initial success of dinosaurs and moulded terrestrial tetrapod
communities for the rest of the Mesozoic.
Acknowledgements
I am indebted to F. Novas (MACN) and R. Martinez
(UNSJ) for allowing the study of these materials. I thank
R. Martinez (UNSJ) and A. Kramarz (MACN) for loan
of specimens here described. Several people allowed me
to study specimens under their care: M. Langer (USP),
C. Malabarba (PUCS), J. Ferigolo (UFRGS), R. Martinez
(UNSJ), E. Vaccari (PULR), A. Kramarz (MACN), J.
Powell (PVL), M. Reguero (MLP), K. Padian, P. Holroyd
and R. Irmis (UCMP). I am also indebted to Fernando
Novas, Randy Irmis, and Julia Desojo who provided
me unpublished photographs of several archosaur speci-
mens very useful for the present work. This study bene-
fited greatly from discussions with and comments from
Max Langer, Diego Pol, Randy Irmis, Federico Agnolin,
Jonathas Bittencourt, Greg Edgecombe, and an anonymous
reviewer during an early draft of the manuscript. I thank
E. L
´
opez-Rolandi for the drawing of Figure 2 and the
silhouettes of Figure 19. This research was partially funded
by the Samuel Welles Fund Grant of the UCMP (to M.
Ezcurra) and the Agencia Nacional de Promoci
´
on Cient
´
ıfica
yT
´
ecnica (to F. Novas). I thank M. Isasi (MACN) for his
help and guidance during the preparation of the holotype
of Chromogisaurus. Access to the free version of TNT 1.1
was possible due to the Willi Henning Society.
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Young, C. C. 1947. On Lufengosaurus magnus (sp. nov.) and addi-
tional finds of Lufengosaurus huenei Young. Palaeontologia
Sinica, 12, 1–53.
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Palaeontologia Sinica, 13, 1–96.
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400 M. D. Ezcurra
Appendix 1: character list
Characters 1–353 correspond to Yates (2007b), 354–361 are
from Smith & Pol (2007), and 362–378 are characters added
here. Modifications in the characters of previous authors are
indicated.
1. Skull to femur ratio: greater than (0); less than (1),
0.6. (Gauthier 1986; Yates 2007b)
2. Lateral plates appressed to the labial side of the
premaxillary, maxillary and dentary teeth: absent
(0); present (1). (Upchurch 1995)
3. Relative height of the rostrum at the posterior
margin of the naris: more than (0) 0.6 of the height
of the skull at the middle of the orbit; less than (1).
(Langer 2004)
4. Foramen on the lateral surface of the premaxillary
body: absent (0); present (1). (Yates 2007b)
5. Distal end of the dorsal premaxillary process:
tapered (0); transversely expanded (1). (Sereno
1999)
6. Profile of premaxilla: convex (0); with an inflection
at the base of the dorsal process (1). (Upchurch
1995)
7. Size and position of the posterolateral process of
premaxilla: large and lateral to the anterior process
of the maxilla (0); small and medial to the anterior
process of the maxilla (1). (Yates 2007a)
8. Relationship between posterolateral process of the
premaxilla and the anteroventral process of the
nasal: broad sutured contact (0); point contact (1);
separated by maxilla (2). (Gauthier 1986; Yates
2007a)
9. Posteromedial process of the premaxilla: absent (0);
present (1). (Rauhut 2003)
10. Shape of the anteromedial process of the maxilla:
narrow, elongated and projecting anterior to lateral
premaxilla-maxilla suture (0); short, broad and
level with lateral premaxilla-maxilla suture (1).
(Yates 2007a)
11. Development of external narial fossa: absent to
weak (0) or well developed with sharp posterior
and anteroventral rims (1). (Yates 2007a)
12. Development of narial fossa on the anterior ramus
of the maxilla: weak and orientated laterally to
dorsolaterally (0); well developed and forming a
horizontal shelf (1). (Upchurch 1995; Yates 2007b)
13. Size and position of subnarial foramen: absent (0),
small (no larger than adjacent maxillary neurovas-
cular foramina) and positioned outside of narial
fossa (1); large and on the rim of, or inside,
the narial fossa (2). (Sereno et al. 1993; Yates
2007b)
14. Shape of subnarial foramen: rounded (0); slot-
shaped (1). (Yates 2007b)
15. Maxillary contribution to the margin of the narial
fossa: absent (0); present (1). (Yates 2007b)
16. Diameter of external naris: less than 0–5 of the
orbital diameter (0); greater than (1). (Wilson &
Sereno 1998)
17. Shape of the external naris (in adults): rounded (0);
subtriangular with an acute posteroventral corner
(1). (Galton & Upchurch 2004)
18. Level of the anterior margin of the external naris:
anterior to the mid-length of the premaxillary body
(0); posterior to (1). (Rauhut 2003)
19. Level of the posterior margin of external naris: ante-
rior to, or level with the premaxilla-maxilla suture
(0); posterior to the first maxillary alveolus (1);
posterior to the midlength of the maxillary tooth
row and the anterior margin of the antorbital fenes-
tra (2). (Wilson & Sereno 1998; Yates 2007b)
20. Dorsal profile of the snout: straight to gently convex
(0); with a depression behind the naris (1). (Yates
2007a)
21. Elongate median nasal depression: absent (0);
present (1). (Sereno 1999)
22. Width of anteroventral process of nasal at its base:
less than (0) or greater than (1) width of anterodor-
sal process at its base. (Sereno 1999; Yates 2007b)
23. Nasal relationship with dorsal margin of antorbital
fossa: not contributing to the margin of the antor-
bital fossa (0), lateral margin overhangs the antor-
bital fossa and forms its dorsal margin (1), overhang
extensive, obscuring the dorsal lachrymal-maxilla
contact in lateral view (2). (Sereno 1999; Yates
2007b)
24. Pointed posterolateral process of the nasal over-
lapping the lachrymal: absent (0) or present (1).
(Sereno 1999)
25. Anterior profile of the maxilla: slopes continuously
towards the anterior tip (0) or with a strong inflec-
tion at the base of the ascending ramus, creating
an anterior ramus with parallel dorsal and ventral
margins (1). (Sereno et al. 1996)
26. Length of anterior ramus of the maxilla: less than
(0), or greater than (1), its dorsoventral depth.
(Sereno et al. 1996)
27. Shape of the main body of the maxilla: tapering
posteriorly (0) or dorsal and ventral margins parallel
for most of their length (1). (Yates 2007a)
28. Shape of the ascending ramus of the maxilla in
lateral view: tapering dorsally (0) or with an antero-
posterior expansion at the dorsal end (1). (Yates
2007a)
29. Anteroposterior length of the antorbital fossa:
greater (0), or less (1), than that of the orbit. (Yates
2003a)
30. Posteroventral extent of medial wall of antorbital
fossa: reaching (0), or terminating anterior to (1),
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A new early dinosaur and reassessment of dinosaur origin and phylogeny 401
the posteroventral corner of the internal antorbital
fenestra (modified from Galton & Upchurch 2004)
31. Development of the antorbital fossa on the ascend-
ing ramus of the maxilla: deeply impressed and
delimited by a sharp, scarp-like rim (0); weakly
impressed and delimited by a rounded rim or a
change in slope (1). (Yates 2007a)
32. Shape of the antorbital fossa: crescentic with a
strongly concave posterior margin that is roughly
parallel to the anterior margin of the antorbital fossa
(0); subtriangular with a straight to gently concave
posterior margin (1); antorbital fossa absent (2).
(Galton 1985; Yates 2007b)
33. Size of the neurovascular foramen at the posterior
end of the lateral maxillary row: not larger than the
others (0); distinctly larger than the others in the
row (1). (Yates 2003a)
34. Direction that the neurovascular foramen at the
posterior end of the lateral maxillary row opens:
posteriorly (0); anteriorly, ventrally or laterally (1).
(Sereno 1999; Yates 2007b)
35. Arrangement of lateral maxillary neurovascular
foramina: linear (0) or irregular (1). (Sereno 1999;
Yates 2007b)
36. Longitudinal ridge on the posterior lateral surface
of the maxilla: absent (0); present (1). (Barrett et al.
2005)
37. Dorsal exposure of the lachrymal: present (0);
absent (1). (Gauthier 1986)
38. Shape of the lachrymal: dorsoventrally short
and blockshaped (0); dorsoventrally elongate and
shaped like an inverted L (1). (Rauhut 2003)
39. Orientation of the lachrymal orbital margin:
strongly sloping anterodorsally (0); erect and close
to vertical (1). (Yates 2007a)
40. Length of the anterior ramus of the lachrymal:
greater than (0); less than (1); half the length of
the ventral ramus, or absent altogether (2). (Galton
1990; Yates 2007b)
41. Web of bone spanning junction between anterior
and ventral rami of lachrymal: absent and antor-
bital fossa laterally exposed (0); present, obscuring
posterodorsal corner of antorbital fossa (1). (Yates
2007a)
42. Extension of the antorbital fossa onto the ventral
end of the lachrymal: present (0); absent (1).
(Wilson & Sereno 1998; Yates 2007b)
43. Length of the posterior process of the prefrontal:
short (0), or elongated (1), so that total prefrontal
length is equal to the anteroposterior diameter of
the orbit. (Galton 1985)
44. Ventral process of prefrontal extending down the
posteromedial side of the lachrymal: present (0);
absent (1). (Wilson & Sereno 1998)
45. Maximum transverse width of the prefrontal: less
than (0), or more than (1), 0.25 of the skull width
at that level. (Galton 1990; Yates 2007b)
46. Shape of the orbit: subcircular (0); ventrally
constricted making the orbit subtriangular (1).
(Wilson & Sereno 1998)
47. Slender anterior process of the frontal intruding
between the prefrontal and the nasal: absent (0);
present (1). (Sereno 1999; Yates 2007b)
48. Jugal–lachrymal relationship: lachrymal overlap-
ping lateral surface of jugal or abutting it dorsally
(0); jugal overlapping lachrymal laterally (1).
(Sereno et al. 1993)
49. Shape of the suborbital region of the jugal: an
anteroposteriorly elongate bar (0); an anteropos-
teriorly shortened plate (1). (Yates 2007a)
50. Jugal contribution to the antorbital fenestra: absent
(0); present (1). (Holtz 1994)
51. Dorsal process of the anterior jugal: present (0);
absent (1). (Rauhut 2003; Yates 2007b)
52. Ratio of the minimum depth of the jugal below the
orbit to the distance between the anterior end of the
jugal and the anteroventral corner of the infratem-
poral fenestra: less than (0) or greater than (1) 0.2.
(Galton 1985; Yates 2007b)
53. Transverse width of the ventral ramus of the postor-
bital: less than (0), or greater than (1) its antero-
posterior width at midshaft. (Wilson & Sereno
1998)
54. Shape of the dorsal margin of postorbital in lateral
view: straight to gently curved (0); with a distinct
embayment between the anterior and posterior
dorsal processes (1). (Yates 2007b)
55. Height of the postorbital rim of the orbit: flush with
the posterior lateral process of the postorbital (0);
raised so that it projects laterally to the posterior
dorsal process (1). (Yates 2007b)
56. Postfrontal bone: present (0); absent (1). (Sereno
et al. 1993)
57. Position of the anterior margin of the infratemporal
fenestra: behind the orbit (0); extends under the rear
half of the orbit (1); extends as far forward as the
midlength of the orbit (2). (Upchurch 1995; Yates
2007b)
58. Frontal contribution to the supratemporal fenes-
tra: present (0); absent (1). (Gauthier 1986; Yates
2007b)
59. Orientation of the long axis of the supratemporal
fenestra: longitudinal (0); transverse (1). (Wilson
& Sereno 1998)
60. Medial margin of supratemporal fossa:
simple smooth curve (0); a projection at the
frontal/postorbital-parietal suture producing a
scalloped margin (1). (Leal et al. 2004)
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402 M. D. Ezcurra
61. Length of the quadratojugal ramus of the squamosal
relative to the width at its base: less than four times
its width (0); greater than (1). (Sereno 1999)
62. Proportion of infratemporal fenestra bordered by
squamosal: more than 0.5 of the depth of the
infratemporal fenestra (0); less than (1). (Yates
2007a)
63. Squamosal–quadratojugal contact: present (0);
absent (1). (Gauthier 1986)
64. Angle of divergence between jugal and squamosal
rami of quadratojugal: close to 90 degrees (0); close
to parallel (1). (Yates 2007a)
65. Length of jugal ramus of quadratojugal: no longer
than (0); longer than (1), the squamosal ramus
(Wilson & Sereno 1998).
66. Shape of the anterior end of the jugal ramus
of the quadratojugal: tapered (0); dorsoventrally
expanded (1). (Wilson & Sereno 1998)
67. Relationship of quadratojugal to jugal: jugal over-
laps the lateral surface of the quadratojugal (0);
quadratojugal overlaps the lateral surface of the
jugal (1); quadratojugal sutures along the ventro-
lateral margin of the jugal (2). (Yates 2007a)
68. Position of the quadrate foramen: on the quadrate-
quadratojugal suture (0); deeply incised into, and
partly encircled by, the quadrate (1); on the
quadrate-squamosal suture, just below the quadrate
head (2). (Rauhut 2003; Yates 2007b)
69. Shape of posterolateral margin of quadrate: slop-
ing anterolaterally from posteromedial ridge (0);
everted posteriorly creating a posteriorly facing
fossa (1); posterior fossa deeply excavated, invad-
ing quadrate body (2). (Wilson & Sereno 1998)
70. Exposure of the lateral surface of the quadrate head:
absent, covered by lateral sheet of the squamosal
(0); present (1). (Sereno et al. 1993)
71. Proportion of the length of the quadrate that is occu-
pied by the pterygoid wing: at least 70% (0); greater
than 70% (1). (Yates 2003a)
72. Depth of the occipital wing of the parietal: less
than (0) or more than (1), 1–5 times the depth of
the foramen magnum. (Wilson & Sereno 1998)
73. Position of foramina for mid-cerebral vein on
occiput: between supraoccipital and parietal (0); on
the supraoccipital (1). (Yates 2003a, 2007b)
74. Postparietal fenestra between supraoccipital and
parietals: absent (0); present (1).
75. Shape of the supraoccipital: diamond-shaped, at
least as high as wide (0); semilunate and wider
than high (1). (Yates 2003b)
76. Orientation of the supraoccipital plate: erect to
gently sloping (0); strongly sloping forward so
that the dorsal tip lies level with the basipterygoid
processes (1). (Galton & Upchurch 2004)
77. Orientation of the paroccipital processes in occipi-
tal view: slightly dorsolaterally directed to horizon-
tal (0); ventrolaterally directed (1). (Rauhut 2003)
78. Orientation of the paroccipital processes in dorsal
view: posterolateral forming a V-shaped occiput
(0); lateral forming a flat occiput (1). (Wilson 2002)
79. Size of the post-temporal fenestra: large fenestra
(0); a small hole much less than half the depth of
the paroccipital process (1). (Yates 2007a)
80. Exit of the mid-cerebral vein: through trigeminal
foramen (0); through a separate foramen anterodor-
sal to trigeminal foramen (1). (Rauhut 2003)
81. Shape of the floor of the braincase in lateral view:
relatively straight with the basal tuberae, basiptery-
goid processes and parasphenoid rostrum roughly
aligned (0); bent with the basipterygoid processes
and the parasphenoid rostrum below the level of
the basioccipital condyle and the basal tuberae (1);
bent with the basal tuberae lowered below the level
of the basioccipital and the parasphenoid rostrum
raised above it (2). (Galton 1990; Yates 2007b)
82. Shape of basal tuberae: knob-like, with basisphe-
noidal component anterior to basioccipital compo-
nent (0); forming a transverse ridge with the
basisphenoidal component lateral to the basioccip-
ital component (1). (Yates 2007a)
83. Length of the basipterygoid processes (from the
top of the parasphenoid to the tip of the process):
less than (0), or greater than (1), the height of the
braincase (from the top of the parasphenoid to the
top of the supraoccipital). (Benton et al. 2000)
84. Ridge formed along the junction of the paraba-
sisphenoid and the basioccipital, between the basal
tuberae: present with a smooth anterior face (0);
present with a median fossa on the anterior face
(1); absent with the basal tuberae being separated
by a deep posteriorly opening U-shaped fossa (2).
(Yates 2007a)
85. Deep septum spanning the interbasipterygoid
space: absent (0); present (1). (Galton 1990)
86. Dorsoventral depth of the parasphenoid rostrum:
much less than (0) or about equal to (1), the trans-
verse width. (Yates 2003a)
87. Shape of jugal process of ectopterygoid: gently
curved (0); strongly recurved and hook-like (1).
(Yates 2003a)
88. Pneumatic fossa on the ventral surface of the
ectopterygoid: present (0); absent (1). (Sereno et al.
1996)
89. Relationship of the ectopterygoid to the pterygoid:
ectopterygoid overlapping the ventral (0), or dorsal
(1), surface of the pterygoid. (Sereno et al.
1993)
90. Position of the maxillary articular surface of the
palatine: along the lateral margin of the bone (0); at
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A new early dinosaur and reassessment of dinosaur origin and phylogeny 403
the end of a narrow anterolateral process due to the
absence of the posterolateral process (1). (Wilson
& Sereno 1998)
91. Centrally located tubercle on the ventral surface of
palatine: absent (0); present (1).
92. Medial process of the pterygoid forming a hook
around the basipterygoid process: absent (0); flat
and blunt-ended (1); bent upward and pointed (2)
(Wilson & Sereno 1998; Yates 2007b)
93. Length of the vomers: less than (0), or more than
(1), 0–25 of the total skull length.
94. Position of jaw joint: no lower than the level of the
dorsal margin of the dentary (0); depressed well
below this level (1). (Sereno 1999)
95. Shape of upper jaws in ventral view: narrow with
an acute anterior apex (0); broad and U-shaped (1).
(Wilson & Sereno 1998)
96. Length of the external mandibular fenestra: more
than (0), or less than (1), 0.1 of the length of the
mandible. (Upchurch 1995; Yates 2007b)
97. Posterior end of dentary tooth row medially inset
with a thick lateral ridge on the dentary form-
ing a buccal emargination: absent (0); present (1).
(Gauthier 1986)
98. Height: length ratio of the dentary: less than (0),
or greater than (1), 0.2. (Benton et al. 2000; Yates
2007b)
99. Orientation of the symphyseal end of the dentary:
in line with the long axis of the dentary (0); strongly
curved ventrally (1). (Sereno 1999)
100. Position of first dentary tooth: adjacent to symph-
ysis (0); inset one tooth’s width from the symphysis
(1). (Sereno 1999)
101. Dorsoventral expansion at the symphyseal end of
the dentary: absent (0); present (1). (Wilson &
Sereno 1998)
102. Splenial foramen: absent (0); present and enclosed
(1); present and open anteriorly (2). (Rauhut 2003)
103. Splenial–angular joint: flattened sutured contact
(0); synovial joint surface between tongue-like
process of angular fitting in groove of the splenial
(1). (Sereno et al. 1993)
104. A stout, triangular, medial process of the articular,
behind the glenoid: present (0); absent (1) (Yates
2003a)
105. Length of the retroarticular process: less than (0),
or greater than (1), the depth of the mandible below
the glenoid. (Yates 2003a)
106. Strong medial embayment behind glenoid of the
articular in dorsal view: absent (0); present (1).
(Yates & Kitching 2003)
107. Number of premaxillary teeth: four (0); more than
four (1). (Galton 1990)
108. Number of dentary teeth (in adults): less than 18
(0); 18 or more (1). (Wilson & Sereno 1998; Yates
2007b)
109. Arrangement of teeth within the jaws: linearly
placed, crowns not overlapping (0); imbricated with
distal side of tooth overlapping mesial side of the
succeeding tooth (1). (Yates 2007b)
110. Orientation of the maxillary tooth crowns: erect (0);
procumbent (1). (Gauthier 1986; Yates 2007b)
111. Orientation of the dentary tooth crowns: erect (0);
procumbent (1). (Gauthier 1986; Yates 2007b)
112. Teeth with basally constricted crowns: absent (0);
present (1). (Gauthier 1986)
113. Tooth–tooth occlusal wear facets: absent (0);
present (1). (Wilson & Sereno 1998)
114. Mesial and distal serrations of the teeth: fine and set
at right angles to the margin of the tooth (0); coarse
and angled upwards at an angle of 45 degrees to the
margin of the tooth (1). (Benton et al. 2000)
115. Distribution of serrations on the maxillary and
dentary teeth: present on both the mesial and distal
carinae (0); absent on the posterior carinae (1);
absent on both carinae (2). (Wilson 2002)
116. Long axis of the tooth crowns distally recurved:
present (0); absent (1). (Gauthier 1986)
117. Texture of the enamel surface: entirely smooth (0);
finely wrinkled in some patches (1); extensively
and coarsely wrinkled (2). (Wilson & Sereno 1998;
Yates 2007b)
118. Lingual concavities of the teeth: absent (0); present
(1). (Upchurch 1995)
119. Longitudinal labial grooves on the teeth: absent (0);
present (1). (Upchurch 1998)
120. Distribution of the serrations along the mesial and
distal carinae of the tooth: extend along most of the
length of the crown (0); are restricted to the upper
half of the crown (1). (Yates 2003a)
121. Number of cervical vertebrae: eight or fewer (0);
9–10 (1); 12–13 (2); more than 13 (3). (Wilson &
Sereno 1998; Yates 2007b)
122. Shallow, dorsally facing fossa on the atlantal
neurapophysis bordered by a dorsally everted lateral
margin: absent (0); present (1). (Yates & Kitching
2003)
123. Width of axial intercentrum: less than (0), or greater
than (1), width of axial centrum. (Sereno 1999)
124. Position of axial prezygapophyses: on the antero-
lateral surface of the neural arch (0); mounted
on anteriorly projecting pedicels (1). (Yates
2007a).
125. Posterior margin of the axial postzygapophyses:
overhang the axial centrum (0); flush with the poste-
rior face of the axial centrum (1). (Sereno 1999)
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404 M. D. Ezcurra
126. Length of the axial centrum: less than (0), or at
least (1), three times the height of the centrum.
(Yates 2007a)
127. Length of the anterior cervical centra (cervicals
3–5): no more than (0), or greater than (1), the
length of the axial centrum. (Yates 2007a)
128. Length of middle to posterior cervical centra (cervi-
cals 6–8): no more than (0), or greater than (1), the
length of the axial centrum. (Yates 2007a)
129. Dorsal excavation of the cervical parapophyses:
absent (0); present (1). (Upchurch 1998)
130. Lateral compression of the anterior cervical verte-
brae: centra no higher than they are wide (0);
approximately 1.25 times higher than wide (1).
(Upchurch 1998)
131. Relative elongation of the anterior cervical centra
(cervicals 3–5): lengths of the centra less than 2.5
times the height of their anterior faces (0); lengths
2.5–4 times the height of their anterior faces (1); the
length of at least cervical 4 or 5 exceeds 4 times the
anterior centrum height (2). (Sereno 1999; Yates
2007b)
132. Ventral keels on anterior cervical centra: present
(0); absent (1). (Upchurch 1998; Yates 2007b)
133. Height of the mid cervical neural arches: no more
than (0), or greater than (1), height of the posterior
centrum face. (Yates 2007a)
134. Cervical epipophyses on the dorsal surface of the
postzygapophyses: absent (0); present on at least
some cervical vertebrae (1). (Yates 2007a)
135. Posterior ends of anterior, postaxial epipophyses:
with a free pointed tip (0); joined to the postzy-
gapophysis along their entire length (1). (Yates
2007a)
136. Shape of the epipophyses: tall ridges (0); flattened,
horizontal plates (1). (Yates 2003a)
137. Epipophyses overhanging the rear margin of the
postzygapophyses: absent (0); present in at least
some postaxial cervical vertebrae (1). (Sereno et al.
1993)
138. Anterior spur-like projections on mid-cervical
neural spines: absent (0); present (1). (Yates 2007a)
139. Shape of mid-cervical neural spines: less than
(0), or at least (1), twice as long as high. (Yates
2007b)
140. Shape of cervical rib shafts: short and posteroven-
trally directed (0); longer than the length of their
centra and extending parallel to cervical column
(1). (Sereno 1999)
141. Position of the base of the cervical rib shaft: level
with, or higher than the ventral margin of the
cervical centrum (0) or located below the ventral
margin due to a ventrally extended parapophysis
(1). (Wilson & Sereno 1998)
142. Postzygodiapophyseal lamina in cervical neural
arches 4–8: present (0); absent (1). (Yates 2003a)
143. Laminae of the cervical neural arches 4–8: well
developed tall laminae (0); weakly developed low
ridges (1). (Wilson & Sereno 1998)
144. Shape of anterior centrum face in cervical centra:
concave (0); flat (1); convex (2). (Gauthier 1986;
Yates 2007b)
145. Ventral surface of the centra in the cervicodorsal
transition: transversely rounded (0); with longitu-
dinal keels (1). (Rauhut 2003)
146. Number of vertebrae between cervicodorsal transi-
tion and primordial sacral vertebrae: 15–16 (0); no
more than 14 (1). (Wilson & Sereno 1998; Yates
2007b)
147. Lateral surfaces of the dorsal centra: with, at most,
vague, shallow depressions (0); with deep fossae
that approach the midline (1); with invasive, sharp-
rimmed pleurocoels (2). (Gauthier 1986)
148. Oblique ridge dividing pleural fossa of cervical
vertebrae: absent (0); present (1). (Wilson & Sereno
1998)
149. Laterally expanded tables at the midlength of the
dorsal surface of the neural spines: absent in all
vertebrae (0); present on the pectoral vertebrae (1);
present on the pectoral and cervical vertebrae (2).
(Yates & Kitching 2003)
150. Dorsal centra: entirely amphicoelous to
amphiplatyan (0); first two dorsals are opistho-
coelous (1); anterior half of dorsal column is
opisthocoelous (2).(Wilson & Sereno 1998)
151. Shape of the posterior dorsal centra: relatively elon-
gated for their size (0); strongly axially compressed
for their size (1). (Novas 1993; Yates 2007b)
152. Laminae bounding triangular infradiapophyseal
fossae (chonae) on dorsal neural arches: absent (0);
present (1). (Wilson 1999)
153. Location of parapophysis in first two dorsals: at the
anterior end of the centrum (0); located at the mid-
length of the centrum, within the middle chonos
(1). (Yates 2007a)
154. Parapophyses of the dorsal column completely shift
from the centrum to the neural arch: anterior (0),
or posterior (1), to the thirteenth presacral vertebra.
(Langer 2004)
155. Orientation of the transverse processes of the
dorsal vertebrae: most horizontally directed (0); all
upwardly directed (1). (Upchurch 1998)
156. Contribution of the paradiapophyseal lamina to the
margin of the anterior chonos in mid-dorsal verte-
brae: present (0); prevented by high placement of
parapophysis (1). (Yates 2007b)
157. Hyposphenes in the dorsal vertebrae: absent (0);
present but less than the height of the neural canal
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A new early dinosaur and reassessment of dinosaur origin and phylogeny 405
(1); present and equal to the height of the neural
canal (2). (Gauthier 1986; Yates 2007b)
158. Prezygodiapophyseal lamina and associated ante-
rior triangular fossa (chonos): present on all dorsals
(0); absent in mid-dorsals (1). (Yates 2003a)
159. Anterior centroparapophyseal lamina in dorsal
vertebrae: absent (0); present (1). (Wilson 2002)
160. Prezygoparapophyseal lamina in dorsal vertebrae:
absent (0); present (1). (Yates 2007b)
161. Accessory lamina dividing posterior chonos from
postzygapophysis: absent (0); present (1). (Yates
2007b)
162. Lateral pneumatic fenestra in middle chonos of
middle and posterior dorsal vertebrae opening into
neural cavity: absent (0); present (1). (Wilson &
Sereno 1998)
163. Separation of lateral surfaces of anterior dorsal
neural arches under transverse processes: widely
spaced (0); only separated by a thin midline septum
(1). (Upchurch et al. 2004)
164. Height of dorsal neural arches, from neurocentral
suture to level of zygapophyseal facets: much less
than (0), or subequal to or greater than (1), height
of centrum. (Yates 2007a)
165. Form of anterior surface of neural arch: simple
centroprezygopophyseal ridge (0); broad anteriorly
facing surface bounded laterally by centroprezy-
gopophyseal lamina (1). (Bonaparte 1999)
166. Shape of posterior dorsal neural canal: subcircular
(0); slit-shaped (1). (Wilson & Sereno 1998)
167. Height of middle dorsal neural spines: less than the
length of the base (0); higher than the length of the
base but less than 1–5 times the length of the base
(1); greater than 1–5 times the length of the base
(2). (Bonaparte 1986; Yates 2007b)
168. Shape of anterior dorsal neural spines: lateral
margins parallel in anterior view (0); transversely
expanding towards dorsal end (1). (Yates 2007a)
169. Cross-sectional shape of dorsal neural spines: trans-
versely compressed (0); broad and triangular (1);
square-shaped in posterior vertebrae (2). (Bona-
parte 1986; Yates 2007b)
170. Spinodiapophyseal lamina on dorsal vertebrae:
absent (0); present and separated from spinopostzy-
gapophyseal lamina (1); present and joining spino-
postzygapophyseal lamina to create a composite
posterolateral spinal lamina (2). (Wilson & Sereno
1998)
171. Well developed, sheet-like suprapostzygapophyseal
laminae: absent (0); present on at least the posterior
dorsal vertebrae (1). (Bonaparte 1986)
172. Shape of the spinopostzygapophyseal lamina in
middle and posterior dorsal vertebrae: singular (0);
bifurcated at its distal end (1). (Wilson 2002)
173. Shape of posterior margin of middle dorsal neural
spines in lateral view: approximately straight (0);
concave with a projecting posterodorsal corner (1).
(Yates 2003b)
174. Transversely expanded plate-like summits of poste-
rior dorsal neural spines: absent (0); present (1).
(Novas 1993)
175. Last presacral rib: free (0); fused to vertebra (1).
(Yates 2007a)
176. Sacral rib much narrower than the transverse
process of the first primordial sacral vertebra (and
dorsosacral if present) in dorsal view: absent (0);
present (1). (Yates & Kitching 2003)
177. Number of dorsosacral vertebrae: none (0); one (1);
two (2). (Gauthier 1986; Yates 2007b)
178. Caudosacral vertebra: absent (0); present (1).
(Galton & Upchurch 2004)
179. Shape of the iliac articular facets of the first primor-
dial sacral rib: singular (0); divided into dorsal and
ventral facets separated by a non-articulating gap
(1). (Yates 2007a)
180. Depth of the iliac articular surface of the primordial
sacrals: less than (0), or greater than (1), 0.75 of the
depth of the ilium. (Novas 1992; Yates 2007b)
181. Sacral ribs contributing to the rim of the acetabu-
lum: absent (0); present (1). (Wilson 2002)
182. Posterior and anterior expansion of the trans-
verse processes of the first and second primor-
dial sacral vertebrae, respectively, partly roofing the
intercostal space: absent (0); present (1). (Langer
2004)
183. Length of first caudal centrum: greater than (0), or
less than (1), its height. (Yates 2003a)
184. Length of base of the proximal caudal neural spines:
less than (0), or greater than (1), half the length of
the neural arch. (Gauthier 1986)
185. Position of postzygapophyses in proximal caudal
vertebrae: protruding with an interpostzygapophy-
seal notch visible in dorsal view (0); placed on
either side of the posterior end of the base of the
neural spine without any interpostzygapophyseal
notch (1). (Yates 2003a)
186. A hyposphenal ridge on caudal vertebrae: absent
(0); present (1). (Upchurch 1995)
187. Depth of the bases of the proximal caudal transverse
processes: shallow, restricted to the neural arches
(0); deep, extending from the centrum to the neural
arch (1). (Upchurch 1998)
188. Position of last caudal vertebra with a protruding
transverse process: distal (0), or proximal (1), to
caudal 16. (Wilson 2002)
189. Orientation of posterior margin of proximal caudal
neural spines: sloping posterodorsally (0); vertical
(1). (Novas 1992)
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406 M. D. Ezcurra
190. Longitudinal ventral sulcus on proximal and middle
caudal vertebrae: present (0); absent (1). (Upchurch
1995; Yates 2007b)
191. Length of midcaudal centra: greater than (0), or less
than (1), twice the height of their anterior faces.
(Yates 2003a)
192. Cross-sectional shape of the distal caudal centra:
oval with rounded lateral and ventral sides (0);
square-shaped with flattened lateral and ventral
sides (1). (Yates 2007a)
193. Length of distal caudal prezygapophyses: short,
not overlapping the preceding centrum by more
than a quarter (0); long, overlapping the preceding
centrum by more than a quarter. (Gauthier 1986)
194. Shape of the terminal caudal vertebrae: unfused,
size decreasing toward tip (0); expanded and fused
to form a club-shaped tail (1). (Upchurch 1995)
195. Length of the longest chevron: less than (0), or
greater than (1), twice the length of the preceding
centrum. (Yates 2003a, 2007b)
196. Anteroventral process on distal chevrons: absent
(0); present (1). (Upchurch 1995)
197. Mid-caudal chevrons with a ventral slit: absent (0);
present (1). (Upchurch 1995)
198. Longitudinal ridge on the dorsal surface of the ster-
nal plate: absent (0); present (1). (Upchurch 1998)
199. Anteroposterior length of the acromion process of
the scapula: less than (0), or greater than (1), 1.5
times the minimum width of the scapular blade.
(Wilson and Sereno 1998)
200. Minimum width of the scapula: less than (0), or
greater than (1), 20% of its length. (Gauthier 1986)
201. Posterior margin of the acromion process of the
scapula: rises from the blade at angle that is less
than (0), or greater than (1), 65 degrees from the
long axis of the scapula, at its steepest point. (Novas
1992; Yates 2007b)
202. Width of dorsal expansion of the scapula: less than
(0), or equal to (1), the width of the ventral end of
the scapula. (Pol & Powell 2007)
203. Flat posteroventrally facing surface on the coracoid
between glenoid and coracoid tubercle: absent (0);
present (1). (Yates & Kitching 2003)
204. Coracoid tubercle: present (0); absent (1). (P
´
erez-
Moreno et al. 1994; Yates 2007b)
205. Length of the humerus: less than 55% (0); 55–65%
(1); 65–70% (2); more than 70% (3), of the length
of the femur. (Gauthier 1986; Yates 2007b)
206. Shape of the deltopectoral crest: subtriangular (0);
subrectangular (1). (Gauthier 1986)
207. Length of the deltopectoral crest of the humerus:
less than 30% (0), 30–50% (1), or greater than 50%
(2), of the length of the humerus. (Sereno et al.
1993; Yates 2007b)
208. Shape of the anterolateral margin of the deltopec-
toral crest of the humerus: straight (0); strongly
sinuous (1). (Yates 2003a)
209. Rugose pit centrally located on the lateral surface
of the deltopectoral crest: absent (0); present (1).
(Yates 2007a)
210. Well-defined fossa on the distal flexor surface of the
humerus: present (0); absent (1). (Yates & Kitching
2003)
211. Transverse width of the distal humerus: is less than
(0), or greater than (1), 33% of the length of the
humerus. (Langer 2004)
212. Shape of the entepicondyle of the distal humerus:
rounded process (0) or with a flat distomedially
facing surface bounded by a sharp proximal margin
(1). (Yates 2007a)
213. Length of the radius: greater than (0), or less than
(1), 80% of the humerus. (Langer 2004)
214. Deep radial fossa, bounded by an anterolateral
process, on proximal ulna: absent (0); present (1).
(Wilson & Sereno 1998)
215. Olecranon process on proximal ulna: present (0);
absent (1); greatly enlarged with a separate ossi-
fication forming a strongly striated proximoante-
rior portion (2). (Modified from Wilson & Sereno
1998)
216. Maximum linear dimensions of the ulnare and radi-
ale: exceed that of at least one of the first three distal
carpals (0); less than any of the distal carpals (1).
(Yates 2003a)
217. Transverse width of the first distal carpal: less than
(0), or greater than (1), 120% of the transverse width
of the second distal carpal. (Sereno 1999)
218. Sulcus across the medial end of the first distal
carpal: absent (0); present (1). (Yates 2007a)
219. Lateral end of first distal carpal: abuts (0), or over-
laps (1), second distal carpal. (Yates 2003a)
220. Second distal carpal: does (0), or does not (1),
completely cover the proximal end of the second
metacarpal. (Yates & Kitching 2003)
221. Fifth distal carpal: ossified but similar in size to
other distal carpals (0), ossified but much larger
than other distal carpals (1) or absent (2). (Modified
from Yates 2007a)
222. Length of the manus: less than 38% (0), 38–45%
(1), or greater than 45% (2), of the humerus +
radius. (Sereno et al. 1993; Yates 2007b)
223. Shape of metacarpus: flattened to gently curved
and spreading (0); a colonnade of subparallel
metacarpals tightly curved into a U-shape (1).
(Wilson & Sereno 1998)
224. Proximal width of first metacarpal: less than (0), or
greater than (1), the proximal width of the second
metacarpal. (Gauthier 1986; Yates 2007b)
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225. Minimum transverse shaft width of first
metacarpal: less than (0), or greater than (1), twice
the minimum transverse shaft width of second
metacarpal. (Yates 2007a)
226. Proximal end of first metacarpal: flush with other
metacarpals (0); inset into the carpus (1). (Sereno
1999)
227. Shape of the first metacarpal: proximal width less
than 65% (0), 65–80% (1), 80–100% (2), or greater
than 100% (3), of its length. (Sereno 1999; Yates
2007b)
228. Strong asymmetry in the lateral and medial distal
condyles of the first metacarpal: absent (0); present
(1). (Gauthier 1986)
229. Deep distal extensor pits on the second and third
metacarpals: absent (0); present (1). (Novas 1993)
230. Shape of the distal ends of second and third
metacarpals: subrectangular in distal view (0);
trapezoidal with flexor rims of distal collateral liga-
ment pits flaring beyond extensor rims (1). (Yates
2007a)
231. Shape of the fifth metacarpal: longer than wide at
the proximal end with a flat proximal surface (0);
close to as wide as it is long with a strongly convex
proximal articulation surface (1). (Yates 2003a)
232. Length of the fifth metacarpal: less than (0), or
greater than (1), 75% of the length of the third
metacarpal. (Upchurch 1998)
233. Length of manual digit one: less than (0), or greater
than (1), the length of manual digit two. (Yates
2003a)
234. Ventrolateral twisting of the transverse axis of the
distal end of the first phalanx of manual digit one
relative to its proximal end: absent (0); present but
much less than 60 degrees (1); 60 degrees (2).
(Sereno 1999)
235. Length of the first phalanx of manual digit one: less
than (0), or greater than (1), the length of the first
metacarpal. (Gauthier 1986)
236. Shape of the proximal articular surface of the first
phalanx of manual digit one: rounded (0); with an
embayment on the medial side (1). (Sereno 1999;
Yates 2007b)
237. Shape of the first phalanx of manual digit one: elon-
gate and subcylindrical (0); strongly proximodis-
tally compressed and wedge-shaped (1). (Wilson
2002)
238. Length of the penultimate phalanx of manual digit
two: less than (0), or greater than (1), the length of
the second metacarpal. (Rauhut 2003)
239. Length of the penultimate phalanx of manual digit
three: less than (0), or greater than (1), the length
of the third metacarpal. (Rauhut 2003)
240. Shape of non-terminal phalanges of manual digits
two and three: longer than wide (0) or as long as
wide (1) (Yates 2003a).
241. Shape of the unguals of manual digits two and
three: straight (0); strongly curved with tips project-
ing well below flexor margin of proximal articular
surface (1). (Sereno et al. 1993)
242. Length of the ungual of manual digit two: greater
than the length of the ungual of manual digit
one (0); 75–100% of the ungual of manual
digit one (1); less than 75% of the ungual of
manual digit one (2); the ungual of manual
digit two is absent (3). (Gauthier 1986; Yates
2007b)
243. Phalangeal formula of manual digits two and three:
three and four, respectively (0); with at least one
phalanx missing from each digit (1). (Wilson &
Sereno 1998; Yates 2007b)
244. Phalangeal formula of manual digits four and five:
greater than (0), or less than (1), 2–0, respectively.
(Gauthier 1986)
245. Dorsal margin of the ilium in lateral view: straight
(0); concave (1); convex (2). (Modified from
Gauthier 1986 and Ezcurra 2006)
246. Anterior extent of preacetabular process of ilium:
does not (0), or does (1), project further forward
than anterior end of the pubic peduncle. (Yates
2003a)
247. Shape of the preacetabular process: blunt and rect-
angular (0); with a pointed, projecting anteroventral
corner and a rounded dorsum (1). (Sereno 1999;
Yates 2007b)
248. Depth of the preacetabular process of the ilium:
much less than (0), or subequal to (1), the depth
of the ilium above the acetabulum. (Gauthier 1986;
Yates 2007b)
249. Length of preacetabular process of the ilium: less
than (0), or greater than (1), twice its depth. (Yates
2007a)
250. Buttress between preacetabular process and the
supraacetabular crest of the ilium: absent (0);
present (1). (Gauthier 1986; modified from Yates
2007b)
251. Medial wall of acetabulum: fully closing acetab-
ulum with a triangular ventral process between
the pubic and ischial peduncles (0); partially open
acetabulum (1); fully open acetabulum with medial
ventral margin closely approximating lateral rim
of acetabulum (2). (Gauthier 1986; modified from
Yates 2007b)
252. Length of the pubic peduncle of the ilium: less than
(0), or greater than (1), twice the anteroposterior
width of its distal end. (Sereno 1999)
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408 M. D. Ezcurra
253. Posteriorly projecting ‘heel’ at the distal end of
the ischial peduncle: absent (0); present (1). (Yates
2003b)
254. Length of the ischial peduncle of the ilium: simi-
lar to pubic peduncle (0); much shorter than pubic
peduncle (1); virtually absent so that the chord
connecting the distal end of the pubic peduncle with
the ischial articular surface contacts the postacetab-
ular process (2). (Upchurch et al. 2004)
255. Length of the postacetabular process of the ilium:
between 40 and 100% of the distance between the
pubic and ischial peduncles (0); less than 40% of
this distance (1); more than 100% of this distance
(2). (Yates 2007a)
256. Well developed brevis fossa with sharp margins on
the ventral surface of the postacetabular process of
the ilium: absent (0); present, being lateroventrally
facing (1); present, being directly ventrally facing
(2). (Modified from Gauthier 1986)
257. Anterior end of brevis shelf: not connected to (0), or
joining (1) supracetabular crest. (Ezcurra & Novas
2007b)
258. Shape of the posterior margin of the postacetabular
process of the ilium: rounded to bluntly pointed (0);
square ended (1); with a pointed ventral corner and
a rounded posterodorsal margin (2). (Yates 2003b)
259. Width of the conjoined pubes: less than (0), or
greater than (1), 75% of their length. (Cooper 1984)
260. Pubic tubercle on the lateral surface of the proximal
pubis: present (0); absent (1). (Yates 2003a)
261. Proximal anterior profile of pubis: anterior margin
of pubic apron smoothly confluent with anterior
margin of iliac pedicel (0); iliac pedicel set anterior
to the pubic apron creating a prominent inflection in
the proximal anterior profile of the pubis (1). (Yates
2007a)
262. Minimum transverse width of the pubic apron:
much more than (0), or less than (1), 40% of the
width across the iliac peduncles of the ilium. (Yates
2007a)
263. Position of the obturator foramen of the pubis: at
least partially occluded by the iliac pedicel (0), or
completely visible (1), in anterior view. (Galton &
Upchurch 2004)
264. Lateral margins of the pubic apron in anterior view:
straight (0); concave (1). (Yates & Kitching 2003)
265. Orientation of distal third of the blades of the pubic
apron: confluent with the proximal part of the pubic
apron (0); twisted posterolaterally relative to proxi-
mal section so that the anterior surface turns to face
laterally (1). (Langer 2004)
266. Orientation of the entire blades of the pubic apron:
transverse (0); twisted posteromedially (1). (Wilson
& Sereno 1998)
267. Anteroposterior expansion of the distal pubis:
absent (0), less than 15% (1), or greater than 15%
(2), of the length of the pubis. (Gauthier 1986; Yates
2007b)
268. Notch separating posteroventral end of the ischial
obturator plate from the ischial shaft: present (0);
absent (1). (Rauhut 2003)
269. Elongate interischial fenestra: absent (0); present
(1). (Yates 2003b)
270. Longitudinal dorsolateral sulcus on proximal
ischium: absent (0); present (1). (Yates 2003a)
271. Shape of distal ischium: broad and plate-like, not
distinct from obturator region (0); with a discrete
rod-like distal shaft (1). (Yates 2007a)
272. Length of ischium: less than (0) or greater than (1)
that of the pubis. (Salgado et al. 1997)
273. Ischial component of acetabular rim: larger than
(0), or equal to (1), the pubic component. (Galton
& Upchurch 2004)
274. Shape of the transverse section of the ischial shaft:
ovoid to subrectangular (0); triangular (1). (Sereno
1999)
275. Orientation of the long axes of the transverse
section of the distal ischia: meet at an angle (0);
are coplanar (1). (Wilson & Sereno 1998)
276. Depth of the transverse section of the ischial shaft:
much less than (0), or at least as great as (1), the
transverse width of the section. (Wilson & Sereno
1998)
277. Distal ischial expansion: absent (0); present (1).
(Holtz 1994)
278. Transverse width of the conjoined distal ischial
expansions: greater than (0), or less than (1), their
sagittal depth. (Yates 2003a)
279. Length of the hindlimb: greater than (0), or less
than (1), the length of the trunk. (Gauthier 1986)
280. Longitudinal axis of the femur in lateral view:
strongly bent with an offset between the proximal
and distal axes greater than 15 degrees (0); weakly
bent with an offset of less than 10 degrees (1);
straight (2). (Cooper 1984)
281. Shape of the cross-section of the mid-shaft of the
femur: subcircular (0); strongly elliptical with the
long axis orientated mediolaterally (1). (Wilson &
Sereno 1998)
282. Angle between the long axis of the femoral head
and the transverse axis of the distal femur: about 30
degrees (0); close to 0 degrees (1). (Carrano 2000)
283. Shape of femoral head: roughly rectangular in
profile with a sharp medial distal corner (0); roughly
hemispherical with no sharp medial distal corner
(1). (Yates 2007a)
284. Posterior proximal tubercle on femur: well devel-
oped (0); indistinct to absent (1). (Novas 1996)
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285. Shape of the lesser trochanter: small rounded tuber-
cle (0); proximodistally orientated, elongate ridge
(1); absent (2). (Gauthier 1986; Yates 2007b)
286. Position of proximal tip of lesser trochanter: level
with (0), or distal to (1), the femoral head. (Galton
& Upchurch 2004)
287. Projection of the lesser trochanter: just a scar upon
the femoral surface (0); a raised process (1). (Yates
2007a)
288. Transverse ridge extending laterally from the lesser
trochanter: absent (0); present (1). (Rowe 1989)
289. Height of the lesser trochanter in cross section: less
than (0), or at least as high as (1), basal width.
(Galton 1990; Yates 2007b)
290. Position of the lesser trochanter: near the centre of
the anterior face (0), or close to the lateral margin
(1), of the femoral shaft in anterior view. (Yates
2007a)
291. Visibility of the lesser trochanter in posterior view:
not visible (0); visible (1). (Galton & Upchurch
2004)
292. Height of the fourth trochanter: a low rugose ridge
(0); tall crest (1). (Reversed from Gauthier 1986)
293. Position of the fourth trochanter along the length of
the femur: in the proximal half (0); straddling the
midpoint (1). (Galton 1990)
294. Symmetry of the profile of the fourth trochanter of
the femur: subsymmetrical without a sharp distal
corner (0); asymmetrical with a steeper distal slope
than the proximal slope and a distinct distal corner
(1). (Langer 2004)
295. Shape of the profile of the fourth trochanter of
the femur: rounded (0); subrectangular (1). (Yates
2007a)
296. Position of fourth trochanter along the mediolat-
eral axis of the femur: centrally located (0); on the
medial margin (1). (Galton 1990)
297. Extensor depression on anterior surface of the distal
end of the femur: absent (0); present (1). (Molnar
et al. 1990)
298. Size of the medial condyle of the distal femur: sube-
qual to (0), or larger than (1), the fibular + lateral
condyles. (Wilson 2002; Yates 2007b)
299. Tibia: femur length ratio: greater than 1.0 (0);
between 0.6 and 1.0 (1); less than 0.6 (2). (Gauthier
1986; Yates 2007b)
300. Orientation of cnemial crest: projects anteriorly to
anterolaterally (0); projecting laterally (1). (Wilson
& Sereno 1998)
301. Paramarginal ridge on lateral surface of cnemial
crest: absent (0); present (1). (Yates 2007b)
302. Position of the tallest point of the cnemial crest:
close to the proximal end of the crest (0); about
half-way along the length of the crest, creating an
anterodorsally sloping proximal margin of the crest
(1). (Yates 2007a)
303. Proximal end of tibia with a flange of bone
that contacts the fibula: absent (0); present (1).
(Gauthier 1986)
304. Position of the posterior end of the fibular condyle
on the proximal articular surface tibia: anterior to
(0) or level with (1), the posterior margin of proxi-
mal articular surface. (Yates 2007a)
305. Shape of the proximal articular surface of the tibia:
ovoid, anteroposteriorly longer than transversely
wide (0); subcircular and as wide transversely as
anteroposteriorly long (1). (Wilson & Sereno 1998)
306. Transverse width of the distal tibia: subequal to
(0), or greater than (1), its anteroposterior length.
(Gauthier 1986)
307. Anteroposterior width of the lateral side of the
distal articular surface of the tibia: as wide (0),
or narrower than (1), the anteroposterior width of
the medial side. (Yates 2007a)
308. Relationship of the posterolateral process of the
distal end of the tibia with the fibula: not flaring
laterally and not making significant contact with
the fibula (0); flaring laterally and backing the fibula
(1). (Yates 2007a)
309. Shape of the distal articular end of the tibia in distal
view: ovoid (0); subrectangular (1). (Yates 2007a)
310. Shape of the anteromedial corner of the distal
articular surface of the tibia: forming a right
angle (0); forming an acute angle (1). (Langer
2004)
311. Position of the lateral margin of descending
posteroventral process of the distal end of the tibia:
protrudes laterally at least as far as (0), or set well
back from (1), the anterolateral corner of the distal
tibia. (Wilson & Sereno 1998)
312. A triangular rugose area on the medial side of the
fibula: absent (0) or present (1) (Wilson & Sereno
1998)
313. Transverse width of the midshaft of the fibula:
greater than 0.75 (0), between 0.5 and 0.75 (1),
or less than 0.5 (2), of the transverse width of the
midshaft of the tibia. (Langer 2004)
314. Position of fibular trochanter: on anterior surface
of fibula (0); laterally facing (1); anteriorly facing
but with strong lateral bulge (2). (Wilson & Sereno
1998; Yates 2007b)
315. Depth of the medial end of the astragalar body in
anterior view: roughly equal to the lateral end (0);
much shallower creating a wedge-shaped astragalar
body (1). (Wilson & Sereno 1998)
316. Shape of the posteromedial margin of the astragalus
in dorsal view: forming a moderately sharp corner
of a subrectangular astragalus (0); evenly rounded
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410 M. D. Ezcurra
without formation of a posteromedial corner (1).
(Wilson & Sereno 1998)
317. Dorsally facing horizontal shelf forming part of the
fibular facet of the astragalus: present (0); absent
with a largely vertical fibular facet (1). (Sereno
1999)
318. Pyramidal dorsal process on the posteromedial
corner of the astragalus: absent (0); present (1).
(Yates 2007a)
319. Shape of the ascending process of the astragalus:
anteroposteriorly deeper than transversely wide (0);
transversely wider than anteroposteriorly deep (1).
(Yates 2007a)
320. Posterior extent of ascending process of the astra-
galus: well anterior to (0), or close to the posterior
margin of (1), the astragalus. (Wilson & Sereno
1998)
321. Sharp medial margin around the depression poste-
rior to the ascending process of the astragalus:
absent (0); present (1) (Novas 1996)
322. Buttress dividing posterior fossa of astragalus and
supporting ascending process: absent (0); present
(1). (Wilson & Sereno 1998)
323. Vascular foramina set in a fossa at the base of the
ascending process of the astragalus: present (0);
absent (1). (Wilson & Sereno 1998)
324. Transverse width of the calcaneum: greater than
(0), or less than (1), 30% of the transverse width of
the astragalus. (Yates & Kitching 2003)
325. Lateral surface of calcaneum: simple (0); with a
fossa (1). (Yates 2007a)
326. Medial peg of calcaneum fitting into astragalus:
present, even if rudimentary (0); absent (1). (Sereno
et al. 1993)
327. Calcaneal tuber: large and well developed (0);
highly reduced to absent (1). (Yates 2007a)
328. Shape of posteromedial heel of distal tarsal four
(lateral distal tarsal): proximodistally deepest part
of the bone (0); no deeper than the rest of the bone
(1). (Sereno et al. 1993)
329. Shape of posteromedial process of distal tarsal four
in proximal view: rounded (0); pointed (1). (Langer
2004)
330. Ossified distal tarsals: present (0); absent (1).
(Gauthier 1986)
331. Proximal width of the first metatarsal: less than (0),
or at least as great as (1), the proximal width of the
second metatarsal. (Wilson & Sereno 1998; Yates
2007b)
332. Orientation of proximal articular surface of
metatarsal one: horizontal (0); sloping proximo-
laterally relative to the long axis of the bone (1).
(Wilson 2002)
333. Orientation of the transverse axis of the distal end
of metatarsal one: horizontal (0); angled proximo-
medially (1). (Wilson 2002)
334. Shape of the medial margin of the proximal surface
of the second metatarsal: straight (0); concave (1).
(Sereno 1999; Yates 2007b)
335. Shape of the lateral margin of the proximal surface
of the second metatarsal: straight (0); concave (1).
(Sereno 1999; Yates 2007b)
336. Length of the third metatarsal: greater than (0),
or less than (1), 40% of the length of the tibia.
(Gauthier 1986)
337. Minimum transverse shaft diameters of third and
fourth metatarsals: greater than (0), or less than
(1), 60% of the minimum transverse shaft diameter
of the second metatarsal. (Wilson & Sereno 1998)
338. Transverse width of the proximal end of the fourth
metatarsal: less than (0), or at least (1), twice the
anteroposterior depth of the proximal end. (Sereno
1999, Yates 2007b)
339. Transverse width of the proximal end of the fifth
metatarsal: less than 25% (0), between 30 and 49%
(1), or greater than 50% (2), of the length of the
fifth metatarsal. (Sereno 1999; Yates 2007b)
340. Transverse width of distal articular surface of
metatarsal four in distal view: greater (0), or less
(1), than anteroposterior depth. (Sereno 1999)
341. Pedal digit five: large (fifth metatarsal at least 70%
of fourth metatarsal); robust and weight bearing (0);
reduced, non-weight bearing (1). (Reversed from
Wilson & Sereno 1998)
342. Length of non-terminal pedal phalanges: all longer
than wide (0); proximal-most phalanges longer than
wide, more distal phalanges are as wide as long (1);
all non-terminal phalanges as wide, if not wider,
than long (2). (Wilson & Sereno 1998; Yates 2007b)
343. Length of the first phalanx of pedal digit one:
greater than (0), or less than (1), the length of the
ungual of pedal digit one. (Yates & Kitching 2003)
344. Length of the ungual of pedal digit one: less than at
least some non-terminal phalanges (0); longer than
all non-terminal phalanges (1). (Yates 2007a)
345. Shape of the ungual of pedal digit one: shallow,
pointed, with convex sides and a broad ventral
surface (0); deep, abruptly tapering, with flattened
sides and a narrow ventral surface (1). (Wilson &
Sereno 1998)
346. Shape of proximal articular surface of pedal
unguals: proximally facing, visible on medial and
lateral sides (0); proximomedially facing and visi-
ble only in medial view, causing medial deflec-
tion of pedal unguals in articulation (1). (Wilson
& Sereno 1998)
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A new early dinosaur and reassessment of dinosaur origin and phylogeny 411
347. Penultimate phalanges of pedal digits two and three:
well developed (0); reduced disc-shaped elements
if they are ossified at all (1). (Wilson & Sereno
1998)
348. Shape of the unguals of pedal digits two and three:
dorsoventrally deep with a proximal articulating
surface that is at least as deep as it is wide (0);
dorsoventrally flattened with a proximal articulat-
ing surface that is wider than deep (1). (Wilson &
Sereno 1998)
349. Length of the ungual of pedal digit two: greater than
(0), between 90 and 100% of (1), or less than 90%
of (2), the length of the ungual of pedal digit one.
(Gauthier 1986; Yates 2007b)
350. Size of the ungual of pedal digit three: greater than
(0), or less than (1), 85% of the ungual of pedal
digit two in all linear dimensions. (Yates 2003a)
351. Number of phalanges in pedal digit four: four (0);
fewer than four (1). (Gauthier 1986)
352. Phalanges of pedal digit five: present (0); absent
(1). (Gauthier 1986)
353. Femoral length: less than 200 mm (0); between 200
and 399 mm (1); between 400 and 599 mm (2);
between 600 and 799 mm (3); between 800 and
1000 mm (4); greater than 1000 mm. (Yates 2004,
2007b)
354. Lateral extent of ventrolateral flange on plantar
surface of metatarsal II in proximal aspect: simi-
lar in development to ventromedial flange (0); well
developed, extending further laterally than ventro-
medial flange extends medially (1). (Smith & Pol
2007)
355. Distal articular surface of astragalus: relatively flat
or weakly convex (0); extremely convex and ‘roller
shaped’ (1). (Smith & Pol 2007)
356. Distal surface of tibiofibular crest: as deep antero-
posteriorly as wide mediolaterally or deeper (0);
wider mediolaterally than deep anteroposteriorly
(1). (Smith & Pol 2007)
357. Well developed facet on proximolateral corner of
plantar ventrolateral flange of metatarsal II for artic-
ulation with medial distal tarsal: absent (0); present
(1). (Smith & Pol 2007)
358. Proximal outline of metatarsal III: subtriangu-
lar with acute or rounded posterior border (0);
subtrapezoidal, with posterior border broadly
exposed in plantar view (1). (Smith & Pol 2007)
359. Angle formed by the anterior and anteromedial
borders of metatarsal IV: obtuse (0); right angle,
or acute (1). (Smith & Pol 2007)
360. Well developed tibiofibular crest on distal femur:
absent (0); present (1). (Smith & Pol 2007)
361. Shaft of metatarsal I: closely appressed to
metatarsal II throughout its length (0); only
closely appressed proximally, with space between
metatarsals I and II distally (1). (Smith & Pol 2007)
362. Muscle origin areas (Mm. flexor tibialis and iliotib-
ialis) on the posterior portion of the postacetabular
process of the ilium: smooth or as a rectangular
rugosity (0); strong trapezoidal rugosity extended
along the whole height of the posterior third of the
process (1).
363. Supraacetabular crest of ilium: not extended along
the pubic peduncle or only at the base of the pedun-
cle (0); extended along the pubic peduncle as a faint
ridge (1); extended along the entire pubic peduncle
and contacts the distal end as a well developed crest
(2).
364. Subnarial gap (i.e. posterior part of premaxillary
alveolar margin edentelous, resulting in an inter-
ruption of the upper tooth row): absent (0); present
(1). (Gauthier 1986)
365. Alveolar margin of anterior-most maxilla: relatively
straight or slightly convex (0); strongly but gradu-
ally upturned from an extension of more than three
teeth along the alveolar margin and orienting the
first maxillary alveolus anteroventrally (1); sharply
mediodorsally upturned in the anterior-most tip of
the maxilla and orienting the first maxillary alveo-
lus anteroventrally (2). (Rowe 1989; Tykoski 1998;
Ezcurra & Novas 2007b)
366. Anterior margin of maxillary antorbital fossa:
rounded or pointed (0); squared (1). (Rauhut 2003)
367. Dorsoventrally compressed ridge on lateral surface
of maxilla, forming the ventral border of the antor-
bital fossa (alveolar ridge): absent (0); present (1).
(Rowe & Gauthier 1990)
368. Exposition of the lacrimal antorbital fossa in lateral
view: lateral lamina of bone covering most of the
bone, with antorbital fossa exposed only at the distal
end of the vertical process (0); lateral lamina of
bone only interrupting the fossa near the proximal
end of the ventral ramus and ventrally restricted
to posterior margin of the ventral ramus, with
antorbital fossa laterally exposed along most of
the lacrimal (1). (Modified from Ezcurra & Novas
2007b)
369. Medial distal condyle of metacarpal I: of the same
size (0) or dorsoventrally smaller (1) than the lateral
distal condyle.
370. Metacarpals IV and V ventral to metacarpals I-III:
absent (0); present (1). (Sereno 1993)
371. Supraacetabular crest of ilium: present as a weakly
developed ridge (0); present as a well developed
raised shelf (1); flares lateroventrally to form a
hood-like overhang that hides anterodorsal half
of acetabulum in lateral view (2). (Langer 2004;
Tykoski 2005)
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412 M. D. Ezcurra
372. Iliac blade in dorsal view: straight or slightly later-
ally curved along the whole of its anteroposte-
rior extension (0); strongly laterally curved, with
a deeply concave lateral border (1).
373. Pubic shaft: posteriorly bowed (0); nearly straight
(1). (Sereno 1999; Ezcurra & Novas 2007b)
374. Femoral head: weakly developed and slightly
inturned, oriented at more than 120
◦
from the main
axis of the femoral shaft (0); strongly inturned,
oriented at less than 120
◦
from the main axis of
the femoral head, and distinctively separated from
the shaft by a well developed femoral neck (1).
(Ezcurra 2006)
375. Posterolateral corner of the distal end of the tibia:
convex (0); concave (1). (Ezcurra 2006)
376. Ungual of pedal digit II: shorter or equal in length
to (0), or longer than (1), pedal phalanx II-2.
377. Distal outline of ischium: roughly semicircular (0);
sub-triangular (1). (Sereno 1999)
378. Orientation of the pubic shaft: anteroventral (0);
ventral, almost perpendicular to the longitudinal
axis of the ilium, or slightly posteroventral (1);
strongly posteroventral, with the pubic shaft paral-
lel to the ischial shaft (2). (Modified from Sereno
1986 and Novas 1992)
Appendix 2: data matrix
Scorings of all the operational taxonomic units analysed in
the present phylogenetic analyses:
Euparkeria
00000000?0000?0000000?000?10010000000000000000
0?00000000000010000000000000000?0000000?00?000
?000000000?1000000000000000000?00000000000???0
000??000000000?00?0?00??0000000000000000000000
0?0?0?????????000?0020000000000??????000000000
01?0?0?0000???00?0000?0000?0010000000000010000
000000?02?000??01000001?000?100000?0000000??0?
00010??0000??0001?000000000?000????????0000000
000000?1?
Crurotarsi
0000000000000?0[01]000000000?0001000000[01]000
0000000000000000000000000000000000000?00000000
0000000000000000000000000000000000000000000000
00???0000??000002000?00?0?00??0000200000000000
0000000000000000[01]00?0[01]0?0020000000000000
00000000000000000000000[01]000000000?0000?0[01
]00000000000000000000000?00?0000000000001?0000
000000?0000000??0?0000000000000000000000000000
00[01]00--0??0000000000000[01]00?0
Marasuchus
00???????0?0????????????0?00???????0??????????
?0???????????????????????????00???00000???????
????????????????00?00000000?1?100000000010???0
0?0??00?000000?00???00??000?00000000?000000000
??01010000000?000?0121000?0000????????????????
??????????????100001000000?0000010000000000000
001000000011000100000000000000001000100100000?
00000000000000000?10?0??00???10????????00?000?
??00000?0
Agnosphitys
??????????????????????????????????????????????
??????????????????????????????????????????????
??????????????????????????????????????????????
??????????????????????????????????????????????
??????????????????????????????????????????????
??????????????00000111002200??????????????????
??????????????????????????????????????????????
???????????????????????????????????????02?????
??1??????
Anchisaurus
10???00??0102?1??11?????111011?010?00101011000
1100111101200?10?????201?001101?1?2002010?????
?10?10?00??100?0000101?1[12]?0111?0011???10010
01111011?10000?010?001100?000??0000000??0100?0
??0?01?00?10?????11[01]0??21100101100??0??2001
011100100201000002000[01]10102100000?111110001
0011?001010000101101000010[01]1110100000011011
1?1?01?010???10111?0?01??0011?1010000010011??0
????1020000??01?11?11
Antetonitrus
?1????????????????????????????????????????????
??????????????????????????????????????????????
???????????????????1?1012000????????0?[01]1???
?????0??00?000001??00210010010121001000???????
?10000?01100???0?0011??31100010110??????0010?3
100???1010?????????????????????111010001??????
??????1110111100111111110100000011011101??????
???????????1011110????[12]1?00?0????31?100??1?
??????????110??
Barapasaurus
??????????????????????????????????????????????
??????????????????????????????????????????????
???????????????????1?111211???????????1?1????0
0??002??100101??00201101111120121100?0[12]1001
?10?11??1????????101?00?1???????11????????????
?????????????????21110021011000011110011???111
10010???????????????????1?1?1?????????1?1?????
??1?????????0???????????1?1??????5????????01??
?????0?11?1?
Blikanasaurus
??????????????????????????????????????????????
??????????????????????????????????????????????
??????????????????????????????????????????????
??????????????????????????????????????????????
??????????????????????????????????????????????
??????????????????????????????????????????????
???????????????????????0000?0110111?1?00001011
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A new early dinosaur and reassessment of dinosaur origin and phylogeny 413
01011100101111112012110000100?211?0?1?1???????
?????????
Camelotia
??????????????????????????????????????????????
??????????????????????????????????????????????
???????????????????????????????????????1??????
?????0??0??001??002100000000??00?0??????????1?
??0??011??????????????????????????????????????
?????????????????????????????1??????????1??001
11?111011110111?1??110?000000?????????????????
???????????????????[12]???000????5????????????
????????????
Cetiosaurus
1?????????????????????????????????????????????
???????????01?????????????????????????????????
????????????????????????????2??001111011111010
0100020?2001?10?1020??1011102010100???[12]????
?1001??00100???0111101031100100011???????1????
?????????????????2111002?0210?0010?1?011??1101
?00???211112??0???010?111210100010010111??????
?????????????????????????????????5????????????
????????????
Chindesaurus
??????????????????????????????????????????????
??????????????????????????????????????????????
????????????????????????????????????0?????????
?????01?0??0?1??0?1??????000??00?????000???1??
0????1000?????????????????????????????????????
?????????????????????0???001??????0???????????
???0000101110001011100?????10111100???01?11010
0?????????????????????????????1??????0?01?????
??10?10??
Coloradisaurus
?00?1002?0102?111111?1??1110?1111000?10??00?00
1?01110101?100100100?1011011011???110111???0?1
?100101101011101100101010000?1?00?110020010001
1?0110??00?001?1001100000000000000101110??0100
100?0?????????0110111121?011?????0????????????
??????????????00100021100?0?111011001001111101
11?001011010000101111010000?0110110???011110?0
00101???001110012?101?0000210021?011?110?0000?
?????????
Efraasia
100?1001?010??1?111?112?1110?100???00100100000
??0?10??01?1??1??????10?000?1?????0110100?????
?10010010??11?011001010100001???1?110011010010
11011010000001??001?00000000000000000110000101
000?0110000?0?010011212000111001101022010?1100
0001110100010000100021000201100010000001100101
101000011110000101100010000001101?001?011010?0
?01?1110001??0011?1010000010002??0???000100001
??1111??1
Eoraptor
0001?001?01010?0011000101010000010000110100000
?10110010100?01100001001???0??1???????????????
?000000?0???0?0?00?1000000001?????100000000000
?10????000??00?00???00?000??00000011??10???100
??001?00??000?0100??0?10??00100??????20?00011?
000?0?0100000110100120000211??0??00?0???10?001
1?10??0?0110000101100000?1?0011110??1?0??0????
?01????0?0???00?0010000000??000?0????1?0211111
002001000
Eucnemosaurus
??????????????????????????????????????????????
??????????????????????????????????????????????
??????????????????????????????????????????????
????????0???01??001100100000??00?0??????????10
000?01100?????????11??????????????????????????
?????????????????????????????110???0??????????
???001101?1010?1010110??00000110110???????????
??????????????????????????????[34]????????????
????????10??
Gongxianosaurus
1?????0??????????12???????????????????????????
??????????????????????????????????????????????
??????????????00???1??2121????????????0???????
?????1??0??001??0??????0?0??00000????????????0
??0?0?1?0?000?011???2110????1?1???????????????
??????????????0?100????0??????????????????????
???[12]111?2??????0???1101??????1?0??1???0?1?1
????1?11??010???10?2?0111000020005????????????
????????????
Plateosaurus ingens
??????????????????????????????????????????????
??????????????????????????????????????????????
??????????????????????????????????????????????
??????????????????????????????????????01??01??
??????10??????????????????????????????????????
??????????????????????????????????????????????
???????????????????????00?010?????????????????
???????????????????[01]???0?0????4????????????
???????110??
Guaibasaurus
??????????????????????????????????????????????
??????????????????????????????????????????????
??????????????????????????????????????????????
????????0???01??011001000000??00000??001000?01
000?01?0??[01]00??1?????110????1?0???????0????
110??0?1?00??0?0?000?011100220110010000000010?
1011000000100100001011010100?0?01111100100?011
01?001011100000000101100000000001100?00??002??
????0111?111
Herrerasaurus
00000000?0101000000000000?00010000000000100000
010001010101000100001101000000101?0000000?1000
?00000000?100000000000000000101000100000010000
0?000010000011??0010[01]1000000200000010000010
1110000110010100?1110??01100000000000001200000
010000011011010010000012000000010000010???01?0
1010010000101110001011000100001000010001001001
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414 M. D. Ezcurra
0100000011000100001001000000000?02000000000100
000111011[01]01
Isanosaurus
??????????????????????????????????????????????
??????????????????????????????????????????????
????????????????????????????????????0??0??????
?????2??10??0???????????????2?011000??????????
?????????????101?0????????????????????????????
??????????????????????????????????????????????
???211112??0???001?1?0????????????????????????
??????????????????????????????3?110??1????????
?????0???
Jingshanosaurus
1001?002??10211111100?0?111011101100?102001??1
?10111011101001000????01100000101?211001000??1
?10110010??11101100101211001????111??010??????
1???10100??0011100?1???0000000000000??10??0100
0000001000000?0010??11201011100??00??0011?3100
100?010001020000100021000002111001002??1100101
10?01001101000010111101010000110110?12011010?0
0??????0101111012010100000010?4???????????????
?????????
Lessemsaurus
??????????????????????????????????????????????
??????????????????????????????????????????????
????????????????????????????????????0??1111010
0??1101?0000011100210010010121000000??????????
??????????????0001???1110010110???????0?1?310?
????1?0??1????0010002100000?11?110002???1??101
10?111011?10???11111?0?000000100101???01101100
1??????????11??12111??00??0???311?????101?????
1?1111??1
Lufengosaurus
100???02???0211?1?11?1111111111010010101101000
0101110101110010?1????0110??0110??01010100?011
010010????0111?11011010100011?0001110020011011
1?01101000200111001100000000000000100110100100
00000[01]10000000001011112[01]1011100110112101
1131001012010001020000100021100002111011002101
1001011000010110100001021110101000011011001001
1110?0001?1110101110012010110000[12][01]004101
110110?00000??1????1?
Mamenchisaurus
11000113?11120110120000000101112??001112010101
011111110120100000111221010000111?201?00?????2
?11[01]0000100100011111111121113?0001110121010
000110002?111010101002011000110201210000011011
1111111011001011111100031100100110110012011000
100011?0?10?1?31?21110021011?00011110011000110
100100211112??0???010?01121010?1??0??????10101
1111??????1101??21?2?021111102??05?1??????????
????????????
Massospondylus
1001100210102111111111211011111010000101101000
110011011111001000102?01?011001011010101??1010
010010110101010110[01]1010110011100?1110020010
0111101101000200111001100000000000000101110100
1[01]00000000000000?01[01]01111201011100110112
1011121001012110000020000100021000200111011001
0011001011100010110100001021010100000011011001
00111101000111110001110012010100000210020?00?0
11??00000????????1
Melanorosaurus
1001?1031010211111101?1110101111???10101011010
11001101011?00000010220110110010??200201001101
1101?00111?1000110?10021100110?010110011011010
010111?0000001??00210000000010000000?020100110
010?001100????0000??21200000110??????00?0?2100
101[12]0?0001020000100021000001111010001???1?0
10110?1110111100111001110100000011011001021101
0100001110010111001?111110000110?301100?11??00
000?0???????
Neosauropoda
1100011311112011012000001010111[02]11101112010
101011[01]11110120100[01]10112221110010111120[
01]200000102011100001201000[01]111111[02]12[01
]112[01]00001110011110100110020121010101[01]02
01110011020121100002100111001111[01]1000010011
1000311001[01]00111100020100000000110001??1?30
021110021021000011110011001110[01]10[01]002111
12??0???010?11121010?11000011111010111111011??
111100210200211111021105?11???110200000?01?100
??
Neotheropoda
00[01]1[01]002[01]010201001100001[01]000000000
000110000000010[01]100[01]01010001[01]0001[012
]0100000010110000001110001000000001?0000000000
0000000101100110000010000[01]10000102000010101
10010000001000000000[12]1000110000000001010000
1000101100000100010002200000110??001001100[12]
010101002000221111010000111110000110100001?011
000100000000[01]011011111002001011000011111000
?0?000001100000000001200000?1?0111111[01]12011
1[01]0
Omeisaurus
110001131111201101200000101011?201001112010101
011111010120100000112221110010111???0?00???1??
?11100001?0?00011101111121113??001110120011010
111002?12101010110201100011020121100?021??1?10
011100100?011111100031100100011??????010000100
0110001001?31021110021011000011110011000111100
100211012??0???010?01021010011?0??111?011010?1
1??1????1111021020021111102?105????????0?00000
??1?1????
Ornithischia
0010000000000?0000000?000?1011000100100?100000
0100100001010000[01]00010010000000010000000001
0010[01]01[01]00000010011100111010000100000000
0010100[01]0000??010000000?00?0?00?00000000000
0000[12]10000000000010000100001001111100000100
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A new early dinosaur and reassessment of dinosaur origin and phylogeny 415
000000000000100000000000000000110102100020011?
?000?000110000000100001?010111102000000000[01]
001110002?01?[01]100000111100000000000[01]1000
000000010?000????01[01][02]000001011010
Patagosaurus
11????????????????????????????????????????????
??????????????????????????????????????????????
??1?00001??????0??0111012111??????110010110000
0110020?2001010?00201?01111120121?00?021001110
0?1?0?100???0?111?00?1100100?11???????????????
??????????????21110021010000011110011001111100
10?211112??0???0011111?101000??0??????????????
??????????????????????????????5????????02?????
??1?11???
Plateosaurus engelhardti
1001100110102011[01]11111211110010110000100101
0101100110011010110010011011011011011110110001
0111100101101011111100101010000110011110011010
0[01]01101101000200111001100000000000000101101
0001000000001000000001001111200011100110112101
0111001002010000010000100021100202101010001111
1001011110000111100001011000100001011111001001
1010100010111000110001111010000010004000000110
[12]000001011110?1
Plateosaurus gracilis
?00??001?0102?110111?1??1110?101??00?10?1010?0
??0?10001101??10??????????????????1???????????
??0??0110?????11100101010?001?????1100??01???0
1101101?00?001?100110000000000000010?101000101
0000001000?00????????1200?11100?1011?101010100
00???10?????0?00100021100202101010001111100101
1??00001111000010110?010000?0??0110???????????
?????????0?????????0?0????????[23]????????0?00
001101111?1?
Plateosauravus
??????????????????????????????????????????????
??????????????????????????????????????????????
???????????????????????????????????10???010010
1?01101?00[12]0011?00110000000001000000??10??0
11???0??110????????0???[23]1110011100?????????
???1????????????????00100021100201?01????????1
1??10110?00001111000010110001000000110110?????
?0???????????????11?0????0??????????4?????????
???????????????
Riojasaurus
1001?00??0102011?110??00111011011000?100001000
?10010?00111001000001101?0?100101?01011??????1
?001000?1??101?100010101000010??11110011010010
1101101000100111001100000000000000101110100100
0000011000??0?01001121210111100111112?01111101
1001010001020?00100021100202111010001101100101
1001011011101011020110100000011011001001101010
0??011?00011100121111000001??13????????0100?00
?011110?0
Ruehleia
??????????????????????????????????????????????
??????????????????????????????????????????????
???????????????????????????????????10???0????0
1???101?002001??00110010000011000000?1100001?0
0?0?0110??????01001111200011100?0100??01011101
000???0??00???001000211000021??11000110110?101
10?101011010000102100010?00?011011001?00001010
0?????????????????????????????3???????????????
?????????
Saturnalia
10????????????????????????1??1????00?100?0????
??????????????10?????1??00???0?0??0?0000??????
????01000??????0000100000000????????0010010010
??01101?00000100001100100000000000000001000101
??0??1000??0??11101111100010102???????????????
??????????????00000111[01]02202100000001001100
10010000001001[01]0001011000100000001010001001
0010100000001000000001011000?000?0010000000001
2?000???11111?1
Shunosaurus
11000113?110201101200000001011?201001112010101
01001101012100011011121010001011?120020???1102
00100000120100011111112121112??01011?1001?1?10
010012?1100001011021?0?001?0201210000?11?00?10
0111011001?111?1?000211001100?11000?2011001?00
0110000??1?3102111002101100001111?01100?111100
100211112??0???000?01121010?01?0????110?101???
11011??1111102002?02111?1021105????????0?00000
??1?10???
Silesaurus
00?0??00?0000?00100000??0?00?0?01010?????????0
010??0????01?????????00?0?0?0000??000000?????1
?00?0?010???0?0000010001000010?00000000000???0
010000000000010100001100000000000000??10000100
000?0?0???????111?1110000100000???????????????
??????????????000001000001001000000000?010100?
0?10000110110001001000100011010000000?0000000?
?11?1??00??000000?10???000?001100000?0?0100?0?
??11000?0
Staurikosaurus
00????????????????????????????????????????????
??????????????????????????????????????????????
?0000000001000?00?0000000000????????00010????0
0?01001?000011?000?00000000020000001??01010110
0000110010????1?1?????????????????????????????
??????????????000001200110001110?010?00010?000
00100001??000?0101?000000001000000001????01???
??????????????????????????????1????????01?????
??1?110?0
Tazoudasaurus
11????????????????????????????????????????????
??????010????????????00?1?????????????????????
?00000001???0??10?111101210???????????????????
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416 M. D. Ezcurra
????02??1??001??102011?001??20111?00????????00
????110????11?????????????????????????????????
????????????????????????????111010001?????????
???[12]1???1?1001?0???????0????0?????????10101
?111??????????????????1??10?1????51??0????????
????????????
Thecodontosaurus
?0????????????????????????1??1??1000??????0?0?
0?0???000????????????10?0?0?1010??011000??????
?00?11010??????1100101010000?1??????000101010?
1?01101?000001??00110000000000000000?1000?0101
100?01000??00?01001121100010100110002201000110
0001010000010100000021000001???0?000??011??010
10?000011110000101100010000000101100??01101010
0????110001110?1?010??00?0????1?0??????020000?
?01?110??
Pantydraco
?0???0????????????[01]00?0???1??1????000100100
000010?100001?10????????00?000?1?10??00100011?
000?00?01010??0000?1001010000001001??110011010
1001101101?00???1????1???????????????????????0
??11?00010000100?????11?1?00??????????????????
?????????????????00100021100001?????????0011??
10110?00??????????1?1?000?0000000?01?001??????
???????????001110011?100000001001?0??00000020?
?01??1????0?
Unaysaurus
100110011010??1?111??1??1010?1011000??????????
??0??00????101???000??0?10??0?10??110100??????
010?10110?????01100101010000???0?1?????0?1?0??
????????0??0?11?00?10000?0??00000?????????????
0????01000?00?010011?1200001100??????1????110?
???211???0??0?????????????????????????????????
?????????????????????????????110110???011010?0
0???????0?110???0??0???0??????1??????????000??
??????0??
Vulcanodon
??????????????????????????????????????????????
??????????????????????????????????????????????
??????????????????????????????????????????????
??????????????????[12]????????????????????1???
???0111?0?00?0?0??01???2110?10?011????????????
???????????????????????210[12]?00?111110001001
11110010?111011110010011?1??20?10001?0???11?10
10110111011??11?01010120011110?121?05?1??00?1?
??????????1???1
Yunnanosaurus
110??002?010?1111110????101?11?01010?10[12]???
??0??0???0111?00??00010??01?0??0010???????????
????10?00010???0?011001012121111???11110011011
0100?0110100000011000110000000001000000?010110
100000?00?0??0??001?0??11200?11100??01??0011?2
101100201000[01]020?001000210000001110100010?1
10010111?0010110100001011010101000010011001?01
1010100011110010111001???11?0000110?2?0???11?0
100000?01?1???0
Glacialisaurus
??????????????????????????????????????????????
??????????????????????????????????????????????
??????????????????????????????????????????????
??????????????????????????????????????????????
??????????????????????????????????????????????
??????????????????????????????????????????????
????0???????????????00????????????????0???1010
[01]????11010111?01???????????????10111011????
????????????
Chromogisaurus
??????????????????????????????????????????????
??????????????????????????????????????????????
??????????????????????????????????????????????
???????????????????????????????????????1000??1
100??1???????????????????????02???????????????
??????????????0????111002202??????????????????
????0??????1???10110??1000000010100010????????
????????????????0??0???000???10????????12?????
??11??11?
MACN-Pv 18649a
??????????????????????????????????????????????
??????????????????????????????????????????????
??????????????????????????????????????????????
??????????????????????????????????????????????
???????????????????????????????000001?00?00110
0?001?0??01?0?????????????????????????????????
??????????????????????????????????????????????
??????????????????????????????????????????????
11???????
Panphagia
?0????????1??????????0?1???????????????????0??
0????????1?1?0???????10?1?1?1?????????????????
?1?0?0?1010000?10?0101000000????????0010010001
1?01101?000?01???01?10000?0?0000000??0???00???
???????00??0??001?????????????????????????????
??????????????0??0?111102201?00??000????1??0??
10?????????????????????001000010100???010?1010
?????????????0??????????????????0??????02?????
??111?1?0
Supplementary material 1
Characters modified from the data matrix
of Yates (2007b)
Character 108: in the data matrix of Yates (2007b) a
third state (2) has been scored for several OTUs, but
only two states were described in the character list of
the paper. Accordingly, state-scorings have been modified
accordantly, i.e. state (1) instead of (2).
Character 215: a third state (2), greatly enlarged olecra-
non with a separate ossification forming a strongly stri-
ated proximoanterior portion, has been added to this char-
acter. The added character state is present in Saturnalia
Downloaded By: [Ezcurra, Martín Daniel] At: 14:41 31 July 2010
A new early dinosaur and reassessment of dinosaur origin and phylogeny 417
(Langer et al. 2007b) and Chromogisaurus. In this regard,
the character-scoring has been modified in Saturnalia but
not in other OTUs.
Character 221: a state was added to this character in
order to represent the large distal carpal five present in
Herrerasaurus and MACN-PV 18649a. Contrasting with
Sereno (1993), new evidences demonstrate that the large
lateral-most distal carpal of Herrerasaurus is actually a
distal carpal 5 (Ezcurra & Novas 2007a, in prep). Thus the
following modification has been made in the scorings of the
following taxa: state (1) instead of (0) in Herrerasaurus and
MACN-PV 18649a. State (2) instead of (1) in Anchisaurus,
Efraasia, Lufengosaurus, Mamenchisaurus, Massospondy-
lus, Neosauropoda, Neotheropoda, Plateosaurus enghel-
hardti, Riojasaurus, Shunosaurus and Thecodontosaurus.
Character 245: the character-states of Gauthier (1986)
and Ezcurra (2006) have been fused in a single character.
As a result, three different character-states define the dorsal
margin of the ilium in the present data matrix. The modified
scorings in the OTUs are detailed here:
Character-state (1) instead of (0): Marasuchus (Sereno
& Arcucci 1994, PVL 3870).
Character-state (2) instead of (1): Barapasaurus,
Cetiosaurus, Eoraptor, Mamenchisaurus, Neosauropoda,
Omeisaurus, Patagosaurus, Shunosaurus (direct modifica-
tion from the scorings of Yates 2007b).
Character 251: medial wall of acetabulum: fully closed
acetabulum with a triangular ventral process between the
pubic and ischial peduncles (0), partially open acetabu-
lum (1), or fully open acetabulum with medial ventral
margin closely approaching the lateral rim of acetabulum
(2) (Gauthier 1986; modified from Yates 2007b). In the
present analysis the presence of a partially open acetabu-
lum was not divided into two distinct states, i.e. a partially
open acetabulum with an either straight or concave ventral
margin. This is because in taxa such as Guaibasaurus, spec-
imens with both straight and concave ventral margins of the
acetabular wall exist (UFRGS PV 0725T) (Fig. 16).
The modification of character 251 resulted in the follow-
ing re-scorings for the OTUs:
Character 251, state (1) instead of state (2): Agnosphitys,
Eoraptor, Herrerasaurus, Ornithischia, Staurikosaurus,
Thecodontosaurus, Pantydraco and Guaibasaurus.
Character 251, state (2) instead of state (3): Anchisaurus,
Barapasaurus, Cetiosaurus, Coloradisaurus, Efraasia,
Jingshaonosaurus, Lessemsaurus, Lufengosaurus,
Mamenchisaurus, Massospondylus, Melanorosaurus,
Neosauropoda, Neotheropoda, Omeisaurus, Patagosaurus,
Plateosaurus engheldensis, Plateosaurus gracilis,
Plateosauravus, Riojasaurus, Ruehlia, Shunosaurus,
Vulcanodon and Yunnanosaurus.
Character 256: well developed brevis fossa with sharp
margins on the ventral surface of the postacetabular process
of the ilium: absent (0); present, being lateroventrally facing
(1); present, being directly ventrally facing (2) (modified
from Gauthier 1986). In non-dinosaur archosauriforms a
concave fossa (brevis fossa) bounded by a lateral rim of
bone (brevis shelf) on the ventral surface of the postac-
etabular process of the ilium is absent. On the other hand,
in the vast majority of dinosaurs, with the exception of
herrerasaurids (Novas 1992), Chindesaurus, Caseosaurus
(Long and Murry 1995), and several sauropodomorphs (e.g.
Pantydraco, Melanorosaurus, Anchisaurus; Yates 2003a,
2007b), the brevis fossa, bounded by posteromedial and
posterolateral rims, are present. In some basal dinosauri-
forms (e.g. Silesaurus, Hayden Quarry silesaurid; Dzik
2003; Irmis et al. 2007; GR 225), a “dinosaurian” brevis
fossa is present, but it is lateroventrally facing, in contrast
with dinosaurs, in which the fossa is directly ventrally
facing. Accordingly, a new character-state has been added
in order to reflect the condition present in Silesaurus and
other basal dinosauriforms.
The modification of character 256 resulted in the follow-
ing re-scorings for the OTUs:
Character 256, state (2) instead of state (1): Agnosphi-
tys, Efraasia, Eoraptor, Guaibasaurus, Massospondy-
lus, Neotheropoda, Ornithischia, Plateosaurus engelhardti,
Plateosaurus gracilis, Plateosauravus, Riojasaurus, and
Saturnalia.
Scorings of character-states of several basal dinosaurs
(Herrerasaurus, Eoraptor, Saturnalia, Guaibasaurus,
Chindesaurus, Neotheropoda) were reviewed based on first-
hand observation of specimens. Additionally, some scorings
were modified based on bibliography (e.g. Agnosphitys).
The reasons for the modification of character-states scored
by Yates (2007b) and its source of information are detailed
below:
Agnosphitys
Character 252: state (1) instead of (0). The pubic peduncle
of the ilium is very long, resembling the condition of Satur-
nalia, Guaibasaurus, and Chromogisaurus, with a length
greater than twice the anteroposteiror length of its distal
articular end (Fraser et al. 2002: fig. 4).
Character 255: State (2) instead of (0). Fraser et al.
(2002).
Crurotarsi
Character 30: state (1) instead of (0). In the most basal
crurotarsans (e.g. Parasuchia, UCMP 27200) the antor-
bital fossa is absent or does not reach the posteroventral
corner of the internal antorbital fenestra, contrasting with
the condition present in some dinosauriforms (e.g. Sile-
saurus, Eoraptor, Neotheropoda).
Guaibasaurus
Character 176: state (0) instead of (?). In Guaibasaurus
(UFRGS PV 0725T) the sacral rib of the first
sacral vertebra is well anteriorly expanded, being more
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418 M. D. Ezcurra
anteroposteriorly wide than the transverse process of the
corresponding vertebra.
Character 177: state (0) instead of (?). The sacrum
of Guaibasaurus is composed of three sacrals. The last
sacral rib contacts the ilium at the posterior end of the
strongly elongated postacetabular process, thus it seems to
be a caudosacral. Accordingly, no dorsosacral is present in
Guaibasaurus (UFRGS PV 0725T).
Character 178: state (1) instead of (?). See character 177.
Characters 179, 180, and 215: state (0) instead of (?).
UFRGS PV 0725T.
Character 185: state (0) instead of (1). In Guaibasaurus
the postzygapophyses of the proximal caudal vertebrae are
separated by a deep interpostzygapophyseal notch visible
in dorsal view (MCN-PV 2355).
Character 189: state (0) instead of (?). UFRGS PV 0725T.
Character 190: state (1) instead of (?). MCN-PV 2355.
Character 192: state (0) instead of (?). UFRGS PV 0725T.
Character 195: state (01) instead of (1). Although in the
holotype the longest chevron exceeds double the length
of its proceeding vertebra (MCN-PV 2355). The longest
chevrons in UFRGS PV 0725T (56 mm) are not greater
than twice the length of the preceding centrum (C6: 37
mm). Accordingly, the character-state of this character is
equivocal in this taxon.
Characters 196 and 197: state (0) instead of (?). UFRGS
PV 0725T.
Character 202: state (?) instead of (0). In the only avail-
able scapula of Guaibasaurus (MCN-PV 2355), both prox-
imal and distal ends are broken, thus the condition of this
character cannot be scored for this taxon.
Characters 206, 207, 213, 228, 229, 235, and 294: state
(1) instead of (?). UFRGS PV 0725T.
Characters 208, 223, 230, 233, 237, 238, 241, 243, 279,
296, and 314: state (0) instead of (?).UFRGS PV 0725T.
Characters 319, 321, 328, and 329: state (1) instead of
(?). MCN-PV 2356.
Characters 334 and 335: state (0) instead of (?). MCN-PV
2355.
Characters 320, 355, 358, and 361: state (0) instead of
(?). MCN-PV 2356.
Character 338: state (1) instead of (?).MCN-PV 2355.
Characters 246, 247, and 249: state (0) instead of (?).
UFRGS PV 0725T (Fig. 16).
Characters 250 and 252: state (1) instead of (?). UFRGS
PV 0725T (Fig. 16).
Character 302: state (?) instead of (0). In none of the
available specimens of Guaibasaurus the proximal surface
of the tibia is preserved. Thus, the condition of this char-
acter is currently unknown for Guaibasaurus (UFRGS PV
0725T, MCN-PV 2355, 2356).
Character 306: state (1) instead of (0). In Guaibasaurus
the transverse width of the distal end of the tibia is greater
than its anteroposterior depth (MCN-PV 2356), contrasting
with Saturnalia and Chromogisaurus.
Character 336: state (0) instead of (1). In the holotype
of Guaibasaurus the proximal surface of the available right
tibia is absent, but the lacking area is only a short portion.
In this specimen, the metatarsal III represents around 45
percent of the length of the tibia (MCN-PV 2355). Accord-
ingly, Guaibasaurus presents the plesiomorphic character-
state of this feature.
Character 340: state (1) instead of (0). In MCN-PV 2355
the distal end of the metatarsal IV is well preserved, and
it is clearly longer dorsoventrally than transversely wide in
distal view.
Herrerasaurus
Character 184: state (1) instead of (0). In Herrerasaurus the
base of the neural spines of the anterior caudal vertebrae
occupy more than the half of the length of the base of their
respective neural arches (PVL 2566).
Character 221: state (0) instead of (1). Comparisons of
Herrerasaurus with MACN-PV 18649a, as well as other
dinosaurs (e.g., Heterodontosaurus), demonstrate that the
identity of the distal carpals of Herrerasaurus was misinter-
preted by Sereno (1993). The putative first distal carpal of
Sereno (1993) seems to be a distal carpal II, and its autapo-
morphic large ventral distal carpal would be the distal carpal
V, as in MACN-PV 18649a (Ezcurra and Novas 2007a). In
addition, PVSJ 380 (referred material of Herrerasaurus;
Sereno 1993) exhibits a distal carpal I directly above the
first metacarpal (contra Sereno 1993), as seen in other
dinosaurs (e.g., MACN-PV 18649a, Heterodontosaurus,
Coelophysis, Mussaurus), supporting the presence of an
ossified fifth distal carpal in Herrerasaurus.
Character 228: state (0) instead of (1). In Herrerasaurus
the distal condyles of the first metacarpal are poorly
asymmetric (PVSJ 373, 380, 407), resembling the condi-
tion of most ornithischians and basal crurotarsans. In
contrast, strongly asymmetric condyles are present in
sauropodomorphs (MACN-PV-SC 4111, MLP 68-II-27-1),
neotheropods (UCMP 37302, QG 1), MACN-PV 18649a
and Heterodontosaurus (Santa Luca 1980; UCMP129614).
Chindesaurus
Character 128: state (?) instead of (1). Only one cervi-
cal vertebra is known from Chindesaurus (PEFO 10395),
and it corresponds to the postaxial series. Since no axis is
currently available, it is impossible to compare the length
of the cervical postaxial vertebrae with that of the axis.
Character 130: state (?) instead of (0). Long & Murry
(1995: 174) reported that the only available cervical of
Chindesaurus is a posterior or mid-cervical. Thus the lateral
compression of the anterior cervical vertebrae is currently
unknown for Chindesaurus.
Character 176: state (0) instead of (?). The sacral rib
of the first primordial sacra of Chindesaurus is strongly
expanded posteriorly, thus the transverse process of this
Downloaded By: [Ezcurra, Martín Daniel] At: 14:41 31 July 2010
A new early dinosaur and reassessment of dinosaur origin and phylogeny 419
sacral vertebra is much narrower than the lateral end of the
rib (PEFO 10395).
Characters 177 and 178: state (0) instead of (?). Chin-
desaurus only has the two primordial sacrals, and no
dorsosacral or caudosacral (Novas 1997; Irmis et al. 2007).
Character 191: state (0) instead of (?). The length of the
available mid-caudal vertebrae of Chindesaurus is greater
than twice the height of their anterior faces (Long & Murry
1995: fig. 177-178).
Character 256: state (0) instead of (1). In Chinde-
saurus the brevis fossa is completely absent (Nesbitt
et al. 2007), contrasting with most basal dinosaurs, except
herrerasaurids (Novas 1993) and some sauropodomorphs
(Yates 2007b).
Character 260: state (?) instead of (1). It is not sure
that the fragments of the proximal pubis and pubic shafts
preserved in PEFO 10395 represent the region in which
the tubercle for insertion of the M. ambiens is located in
other dinosaurs. Thus its presence or absence cannot be
unequivocally evaluated.
Character 282: state (0) instead of (?). GR 226.
Character 292: state (1) instead of (0). In the holo-
type of Chindesaurus, the left femur does not preserve
the shaft and the right one is very badly preserved, thus
the morphology of the fourth trochanter cannot be asserted
(PEFO 10395). A well preserved femur referred to Chin-
desaurus (GR 226; Irmis et al. 2007) exhibits a tall fourth
trochanter, resembling the condition of Chromogisaurus,
Herrerasaurus, Eoraptor and Saturnalia.
Character 294: state (1) instead of (0). In GR 226
(referred material of Chindesaurus;Irmiset al. 2007)
the fourth trochanter is clearly asymmetric (pers. obs.),
resembling the condition of Herrerasaurus, Saturnalia and
Plateosaurus, among other basal saurischians.
Character 295: state (1) instead of (0). In GR 226
(referred material of Chindesaurus;Irmiset al. 2007) the
fourth trochanter has a subrectangular profile rather than a
rounded one (pers. obs.), resembling the condition of basal
saurischians.
Characters 301 and 302: state (?) instead of (0). In the
holotype of Chindesaurus (PEFO 10395), the most proxi-
mal surface of the tibia is not preserved, and the only the
base of the cnemial crest is available. Accordingly, the shape
of the proximal end and lateral surface of the cnemial crest
cannot be scored.
Character 317: state (?) instead of (1). Nesbitt et al.
(2007: fig. 4) reported that the lateral end of the astragalus
of PEFO 10395 is missing. Thus the morphology of the
fibular articular facet of the astragalus cannot be evaluated.
Character 326: state (?) instead of (1). Neither the calca-
neum nor the lateral end of the astragalus is available in
specimens of Chindesaurus (Nesbitt et al. 2007). Thus, the
state of this character cannot be evaluated.
Character 360: state (0) instead of (?). GR 226.
Eoraptor
Character 3: state (0) instead of (1). In Eoraptor the relative
height of the rostrum at the posterior margin of the naris is
more than 0.6 of the height of the skull at the middle of the
orbit (PVSJ 512) (Fig. 17).
Character 4: state (1) instead of (0). The premaxillary
body of Eoraptor bears a distinct foramen above the second
premaxillary tooth (PVSJ 512) (Fig. 17).
Character 8: state (1) instead of (0). In Eoraptor the
posterolateral process of the premaxilla upturns posterodor-
sally, bounding the posteroventral corner of the external
naris as a very long and thin projection (PVSJ 512). The
distal tip of the premaxillary posterolateral process slightly
contacts the anteroventral process of the nasal, but it clearly
differs from the broad suture present in Herrerasaurus and
Silesaurus. Thus, the state of Eoraptor resembles more a
point contact rather than a wide suture (Fig. 17).
Character 23: state (1) instead of (0). In Eoraptor the
lateral margin of the nasal delimits dorsally the maxillary
antorbital fossa forming a distinct rim above it (PVSJ 512).
Character 30: state (0) instead of (1). The posteroven-
tral portion of the maxillary antorbital fossa of Eoraptor
reaches the posteroventral corner of the internal antorbital
fenestra, contrasting with the condition present in most non-
neotheropod dinosaurs (Fig. 17).
Character 34: state (0) instead of (?). Five neurovascular
foramina are present in the horizontal ramus of the maxilla
of Eoraptor (PVSJ 512). The posterior-most foramen is
anteroposteriorly larger than the other five and opens poste-
riorly.
Character 50: state (0) instead of (1). The anterior process
of the jugal does not reach the posteroventral corner of the
antorbital fenestra (PVSJ 512) (Fig. 17).
Character 59: state (?) instead of (0). In the holotype of
Eoraptor,the posterior end of the dorsal skull roof is very
damaged and prevents discerning the morphology of the
supratemporal fenestrae (PVSJ 512).
Character 62: state (1) instead of (0). The squamosal
in the holotype of Eoraptor is broken with its main body
and ventral ramus separated from one another. However,
the ventral ramus of the squamosal is preserved in natural
position and the proportion of the infratemporal fenestra
bordered by the squamosal is much less than 0.5 of the
depth of the infratemporal fenestra (PVSJ 512).
Character 103: state (?) instead of (0). In Eoraptor the
morphology of the medial surface of the mandible is not
available. Thus the shape splenial-angular joint is unknown.
Character 121: state (1) instead of (?). Eoraptor exhibits
ten cervical vertebrae (PVSJ 512).
Character 132: state (0) instead of (1). In Eoraptor the
ventral surface of the cervical vertebrae bears a well devel-
oped longitudinal keel (PVSJ 512).
Character 134: state (0) instead of (1). The cervical verte-
brae of Eoraptor lack epipophyses on the dorsal surface of
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420 M. D. Ezcurra
the postzygapophyses (PVSJ 512), contrasting with most
basal dinosaurs.
Character 155: state (0) instead of (?). In Eoraptor the
transverse processes of the dorsal vertebrae are horizontally
projected (PVSJ 512).
Character 173: state (0) instead of (1). At least some
mid-dorsal vertebrae of PVSJ 512 exhibit a projection at
the posterodorsal corner of the neural spine.
Characters 187, 188, 191, 192, 195–197, 201, 208, 212,
214, 215, 264, 283, 290, 291, 296, 297, 315, 324, and 355:
state (0) instead of (?). PVSJ 512.
Characters 189, 228, 306, 325, and 360: state (1) instead
of (?). PVSJ 512.
Character 206: state (?) instead of (1). The shape of the
deltopectoral crest of the only available humerus is not
preserved in PVSJ 512.
Character 213: state (1) instead of (0). In Eoraptor the
maximum length of the radius represents 64% of the maxi-
mum humeral length (PVSJ 512).
Character 255: state (0) instead of (1). The best later-
ally exposed ilium of PVSJ 512 is the left one; however, its
postacetabular process is broken off so it is lacking its poste-
rior end. Accordingly, it gives the impression of bearing a
short postacetabular process, as occurs in Staurikosaurus.
In the right ilium, which is partially obscured by the right
distal tibia-fibula and tarsals, the postacetabular process is
complete, showing that this process is actually moderately
long, representing 75% of the length of the acetabulum
(length between both pubic and iliac peduncles), rather than
less than 40% of the acetabular length.
Character 258: state (1) instead of (0). The right ilium
of PVSJ 512, bearing a complete postacetabular process, is
square ended (see character 255), resembling the condition
of neotheropods.
Character 277: state (1) instead of (0). The distal end
of the ischium of Eoraptor is anteroposteriorly expanded
(PVSJ 512), as occurs in other eusaurischians such as
Guaibasaurus (MCN-PV 2355), neotheropods (UCMP
37302), and Saturnalia (MCP 3944-PV).
Character 286: state (1) instead of (0). The anterior
trochanter of Eoraptor (PVSJ 512) is situated more distally
than in other basal saurischians, being placed more distally
than the femoral head.
Character 292: state (1) instead of (0). The fourth
trochanter of Eoraptor is a well developed tall crest (PVSJ
512), resembling the condition of other basal dinosaurs such
as Herrerasaurus, Saturnalia, and Chromogisaurus.
Character 302: state (1) instead of (0). In Eoraptor the
tallest point of the tibia is located close to the base of the
cnemial crest, thus it presents an anterodorsally sloping
proximal margin of the crest (PVSJ 512). This condition
contrasts with some other basal dinosaurs, such as Chrom-
ogisaurus, in which the tallest point of the cnemial crest is
situated at the anterior end of the crest.
Character 304: state (0) instead of (1). The proximal
end of the tibia of Eoraptor presents asymmetric posterior
condyles, with the lateral one anterior to the posterior level
of the medial one (PVSJ 512).
Character 307: state (1) instead of (0). The distal end of
the tibia of Eoraptor exhibits a well laterally developed and
anteroposteriorly narrow posterolateral descending process
(PVSJ 512), a morphology which closely resembles that
of Guaibasaurus (MCN-PV 2356). Accordingly, the lateral
side of the distal end of the tibia of Eoraptor is narrower
than the medial side (PVSJ 512).
Neotheropoda
Character 4: state (1) instead of (0). In several basal
neotheropods (Coelophysis,“Syntarsus” Tykoski 1998;
Ezcurra 2007) the lateral surface of the premaxillary body
is pierced by a single nutrient foramina directly above the
second maxillary tooth.
Character 228: state (0) instead of (1). See
Herrerasaurus.
Character 241: state (0) instead of (1). Neotheropods
usually exhibit strongly curved manual unguals of digits
II and III, as occurs in Herrerasaurus (PVSJ 373, 380)
and Guaibasaurus (UFRGS PV 0725T). However, the most
basal known neotheropods present poorly ventrally curved
manual unguals II and III (e.g. Dilophosaurus, Coeloph-
ysis rhodesiensis; UCMP 37302; QG1). In this regard, the
presence of strongly ventrally curved manual unguals II
and III seems to be a character convergently acquired by
herrerasaurids and averostran theropods.
Ornithischia
Character 228: state (0) instead of (1). Butler et al. (2007)
obtained Heterodontosauridae as the sister group of all
other ornithischians, with the exclusion of Pisanosaurus.
Since Heterodontosaurus presents a strong asymmetry in
the distal condyles of the first metacarpal (Santa Luca 1980;
UCMP 129614), this would be the ancestral condition of
Ornithischia within this phylogenetic arrangement.
Character 306: state (0) instead of (1). Pisanosaurus has
been widely considered as the most-basal ornithischian
(e.g., Langer 2004; Langer & Benton 2006; Butler et al.
2007). This taxon presents a sub-quadrangular distal tibia,
a trait that should be the symplesiomorphic condition of
Ornithischia (PVL 2577).
Saturnalia
Character 117: state (0) instead of (1). The anterior teeth
of the preserved dentary of Saturnalia (MACP 3845-PV)
exhibit distally recurved crowns, resembling the condition
of more basal saurischians (Eoraptor, Herrerasaurus;PVSJ
512; Sereno and Novas 1993), Panphagia (Martinez &
Alcober 2009), and Pantydraco (Yates 2003a, figure 8B).
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A new early dinosaur and reassessment of dinosaur origin and phylogeny 421
Character 131: state (1) instead of (0). In the paratype
of Saturnalia MCP 3845-PV, the length of the preserved
anterior postaxial cervical centra is clearly more than 2.5
times the height of its anterior faces, but lower than 4 times.
Accordingly, Saturnalia exhibits state (1) of this character,
but not state (0).
Character 178: state (1) instead of (0). Langer (2003)
described a probable dorsosacral for Saturnalia (MCP
3844-PV), a condition observed in the vast majority of
sauropodomorphs.
Characters 187, 191, 192, 193, 196, 246, 247, 249: state
(0) instead of (?). MCP 3844-PV (first caudal) and MCP
3846-PV.
Character 190: state (1) instead of (?). MCP 3844-PV
(first caudal) and MCP 3846-PV.
Character 215: state (2) instead of (0). A third character-
state (greatly enlarged olecranon with a separate ossifica-
tion forming a strongly striated proximoanterior portion)
has been added for this character, and it is present in Satur-
nalia (Langer et al. 2007b). Accordingly, the scoring for
this character has been modified here for Saturnalia in the
present data matrix.
Character 253: state (01) instead of (0). In MCP 3846-PV
(paratype of Saturnalia; Langer 2003) a posteriorly project-
ing ‘heel’ is present at the distal end of the ischial pedun-
cle. However, the reverse is present in the holotype (MCP
3844-PV) (Langer 2003). Thus, both states are present in
Saturnalia tupiniquim.
Character 288: state (01) instead of (1). In MCP 3846-
PV (paratype of Saturnalia; Langer 2003) the trochanteric
shelf is absent (pers. obs.) in contrast with MCP 3845-PV
(Langer 2003). Thus, both states are present in Saturnalia
tupiniquim.
Silesaurus
Character 177: state (1) instead of (0). Dzik & Sulej (2007)
reported that further preparation of the original materi-
als of Silesaurus revealed that a dorsosacral was added
to the two primordial sacrals, thus this taxon has three
sacrals and not only two as initially described by Dzik
(2003).
Character 256: state (1) instead of (0). In Silesaurus the
postacetabular process bears a well defined brevis fossa, as
occurs in Eoraptor, Saturnalia, Chromogisaurus and other
basal eusaurischians (Langer & Benton 2006).
Character 294: state (0) instead of (1). In Silesaurus the
fourth trochanter is almost symmetric in profile (ZPAL
Ab III 361), contrasting with the asymmetric trochanter
present in ornithischians and basal saurischian dinosaurs,
e.g. Lesothosaurus, Herrerasaurus, Eoraptor, and Chro-
mogisaurus (Sereno 1991; PVSJ 373; MACN-PV 18060;
PVSJ 512).
Character 306: state (1) instead of (0). In Silesaurus
the distal end of the tibia is much transversely wider than
its anteroposterior length, with a well developed postero-
lateral process (Dzik 2003; Langer & Benton 2006), and
clearly does not exhibit a sub-quadrangular distal tibia as
occurs in Herrerasaurus, Saturnalia, Chromogisaurus and
Pisanosaurus.
Pantydraco
Character 117: state (0) instead of (1). The anterior teeth
of the dentary of Pantydraco (Yates 2003a, figure 8B; see
the second crown) exhibit distally recurved crowns, resem-
bling the condition of more basal saurischians (Eorap-
tor, Herrerasaurus; PVSJ 512; Sereno and Novas 1993),
Panphagia (Martinez & Alcober 2009), and Saturnalia
(MCP 3845-PV, see above).
Character 131: state (1) instead of (?). A complete cervi-
cal 4 is available in the holotype of Pantydraco (Yates
2003a, figure 11C). The centrum length of this vertebra
is more than 2.5 times the height of its anterior face, but
lower than 4 times. Accordingly, Pantydraco exhibits state
(1) of this character.
Supplementary material 2
Sources of data for the present cladistic
analysis
States for characters 362-378 were determinated based on
the following sources:
Agnosphitys Fraser et al. (2002)
Anchisaurus Galton (1976), Fedak & Galton (2007)
Barapasaurus unpublished photographs of ISIR specimen
(several numbers)
Chindesaurus cast of PEFO 10395, GR 226, Long & Murry
(1995), Nesbitt et al. (2007)
Chromogisaurus PVSJ 845
Coloradisaurus PVL 3967, Bonaparte (1978)
Crurotarsi UCMP 26699 (Leptosuchus), UCMP 27200
(Smilosuchus), UCMP 36232 (Arizonasaurus), (Presto-
suchus holotype), PULR 04, 057 (Luperosuchus), UCMP
129740 (Hesperosuchus), UCMP 131830 (Kayentasuchus),
UCMP 25962, 25968, 25974, 25978 (Poposaurus), UCMP
27481, 27572, 124586, 140015 (Postosuchus), PVL 4597
(Gracilisuchus), PVL 2561, 3889 (Trialestes), Long &
Murry (1995)
Efraasia unpublished photographs of SMNS 4388, 11838,
12220, 12353a, 12354, 12667, 12668, 12684, 14880,
14881, 17928
Eoraptor PVSJ 512
Euparkeria cast of SAM 5867, Ewer (1965)
Guaibasaurus UFRGS PV 0725T, MCP 2355-PV, 2356-PV,
Bonaparte et al. (1999, 2007)
Herrerasaurus MACN-PV 18060, MLP 61-VIII-2-2, 61-
VIII-2-3, PVSJ 104, 373, 380, 407, PVL 2054, 2453, 2556,
2558, Novas (1993), Sereno (1993), Sereno & Novas (1993)
Lessemsaurus PVL 4822, Pol & Powell 2007
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422 M. D. Ezcurra
Lufengosaurus Young (1941, 1951), Barrett et al. (2005)
Marasuchus PVL 3035, 3036, 3872, Sereno & Arcucci
(1994)
Massospondylus Cooper (1981), Attridge et al. (1985)
Melanorosaurus Yates (2007b), Bonnan & Yates (2007)
Neosauropoda Upchurch et al. (2004)
Neotheropoda UCMP 32101 (Segisaurus) UCMP 34498
(Camposaurus), UCMP 37302 (Dilophosaurus wetherilli),
UCMP 37303 (Dilophosaurus wetherilli), UCMP 77270
(Dilophosaurus wetherilli), UCMP 128659 (“Syntarsus”
kayentakatae), UCMP 129618 (Coelophysis sp.), PULR
076 (Zupaysaurus), casts of QG 1 (Coelophysis rhodesien-
sis), unpublished photographs of CM Coelophysis bauri
specimens, HMN MB R. 2175 (Liliensternus), SMNS
12591 (Procompsognathus)
Omeisaurus Dong et al. (1983), He et al. (1984)
Ornithischia PVL 2577 (Pisanosaurus), UCMP 130580,
130581, 170829 (Scutellosaurus), UCMP 129614 cast of
SAM-K 1332 (Heterodontosaurus), Santa Luca (1980),
Sereno (1991)
Panphagia unpublished photographs of PVSJ 874;
Martinez & Alcober (2009)
Pantydraco unpublished photographs of BMNH P 24, Yates
(2003b)
Patagosaurus MACN-PV-CH 933, 935, Bonaparte
(1986)
Plateosaurus engelhardti unpublished photographs of
SMNS 12949, 12950, 13200, Moser (2003)
Plateosaurus gracilis MACN-PV 10082, unpublished
photographs of SMNS 5715, Galton (1984), Galton and
Upchurch (2004)
Riojasaurus PULR 056, PVL 3808, 3845, 4364, Bonaparte
(1972), Bonaparte and Pumares (1995)
Saturnalia MCP 3844-PV, 3845-PV, 3846-PV, Langer
(2003), Langer et al. (2007a)
Shunosaurus Dong et al. (1983), McIntosh (1990)
Silesaurus unpublished photographs of ZPAL Ab III 361,
III 363, Dzik (2003), Dzik & Sulej (2007)
Staurikosaurus unpublished photographs of MCZ 1669,
Colbert (1970)
Thecodontosaurus Galton and Cluver (1976), Kermack
(1984), Benton et al. (2000)
Unaysaurus Leal et al. (2004)
Yunnanosaurus Young (1942, 1947), Lu et al. (2007)
Supplementary material 3
Synapomorphy list
The following list depicts the unambiguous synapomor-
phies common to the 60 MPTs obtained in the heuris-
tic search, after the exclusion of Agnosphitys (nodes in
bold indicate clades bearing Chromogisaurus apomorphic
character-states):
Node 52 (Dinosauriformes): Character 121 (0 → 1),
Character 204 (0 → 1), Character 250 (0 → 1), Charac-
ter 279 (0 → 1), Character 287 (0 → 1), Character 292
(0 → 1), Character 341 (0 → 1), Character 352 (0 → 1)
Node 53 (Anchisauria): Character 42 (0 → 1), Character
58 (1 → 0), Character 82 (1 → 0), Character 84 (1 → 2),
Character 106 (1 → 0)
Node 54 (Jingshanosaurus + more derived
sauropodomorphs): Character 81 (0 → 2), Character
115 (0 → 2), Character 173 (1 → 0), Character 222
(1 → 0), Character 331 (0 → 1)
Node 55 (Massospondylidae + more derived
sauropodomorphs): Character 14 (0 → 1), Character
31 (0 → 1), Character 40 (0 → 1), Character 52 (0 → 1),
Character 54 (0 → 1), Character 67 (1 → 2), Character
120 (0 → 1), Character 132 (1 → 0), Character 201
(0 → 1), Character 227 (1 → 2), (Character 268 (1 → 0),
Character 286 (1 → 0)
Node 56 (Massopoda): Character 29 (0 → 1), Character 57
(0 → 1), Character 179 (0 → 1), Character 225 (0 →
1),
Character 240 (0 → 1), Character 242 (1 → 2), Character
260 (0 → 1), Character 279 (1 → 0), Character 296 (0 →
1), Character 297 (0 → 1), Character 339 (1 → 2)
Node 57 (Plateosauria): Character 173 (0 → 1), Character
220 (0 → 1)
Node 58 (Ruehleia + more derived sauropodomorphs):
Character 205 (2 → 1), Character 258 (1 → 2)
Node 59 (Plateosauravus + more derived
sauropodomorphs): Character 149 (0 → 2), Charac-
ter 253 (0 → 1), Character 261 (0 → 1), Character 353
(2 → 3)
Node 60 (Efraasia + more derived sauropodomorphs):
Character 137 (0 → 1), Character 177 (0 → 1), Char-
acter 191 (0 → 1), Character 212 (0 → 1), Character 227
(1 → 0), Character 229 (1 → 0), Character 244 (1 → 0),
Character 353 (1 → 2). Some trees: Character 21 (0 → 1),
Character 94 (0 → 1), Character 104 (0 → 1),, Character
195 (1 → 0), Character 256 (0/1 → 2), Character 306 (0
→ 1), Character 343 (0 → 1), Character 352 (1 → 0),
Character 363 (2 → 1)
Node 61 (Thecodontosaurus + Pantydraco + more derived
sauropodomorphs): Character 109 (0 → 1), Character 250
(1 → 0), Character 333 (0 → 1), Character 334 (0 → 1),
Character 335 (0 → 1), Character 339 (1 → 0), Character
349 (0 → 1). Some trees: Character 83 (0 → 1), Charac-
ter 176 (0 → 1), Character 205 (1 → 2), Character 285
(0 → 1), Character 310 (0 → 1), Character 317 (0 → 1)
Node 62 (Sauropodomorpha): Character 1 (0 → 1),
Character 75 (0 → 1), Character 131 (0 → 1), Charac-
ter 142 (0 → 1), Character 143 (0 → 1), Character 184
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A new early dinosaur and reassessment of dinosaur origin and phylogeny 423
(0 → 1), Character 211 (0 → 1), Character 252 (0 →
1), Character 372 (0 → 1). Some tress: Character 274
(0 → 1), Character 304 (1 → 0), Character 363 (1 → 2),
Character 377 (0 → 1)
Node 63 (Eusaurischia): Character 258 (0 → 1).
Some trees (in which Chindesaurus is found within
Theropoda): Character 4 (0 → 1), Character 8 (0 →
1), Character 15 (0 → 1), Character 18 (0 → 1), Char-
acter 19 (0 → 1), Character 25 (0 → 1), Character 38
(0 → 1), Character 102 (1 → 0) Character 217 (0 → 1),
Character 221 (1 → 2), Character 277 (0 → 1), Char-
acter 306 (0 → 1), Character 368 (0 → 1)
Node 64 (Saurischia): Character 11 (0 → 1), Character
13 (0 → 1), Character 77 (0 → 1), Character 127 (0 →
1), Character 157 (0 → 1), Character 221 (0 → 1), Char-
acter 222 (0 →2), Character 229 (0 → 1), Character 244
(0 → 1), Character 286 (0 →1), Character 321 (0 →1)
Node 65 (Dinosauria): Character 134 (0 → 1), Char-
acter 145 (0 → 1), Character 207 (0 → 1), Character
251 (0 → 2), Character 294 (0 → 1), Character 319
(0 → 1), Character 373 (0 → 1), Character 374 (0
→ 1)
Node 66 (Silesaurus + Dinosauria): Character 48
(0 → 1), Character 112 (0 → 1), Character 200 (0 → 1),
Character 203 (0 → 1), Character 205 (2 → 1), Char-
acter 259 (0 → 1), Character 271 (0 → 1), Character
284 (0 → 1), Character 304 (0 → 1), Character 325
(0 → 1), Character 327 (0 → 1), Character 363 (0 →
1), Character 371 (0 → 1). Some trees: Character 256
(0 → 1)
Node 67 (Antetonitrus + Lessemsaurus): Character 161 (0
→ 1), Character 164 (0 → 1), Character 166 (0 → 1),
Character 168 (0 → 1), Character 202 (0 → 1), Character
227 (2 → 3)
Node 68 (Blikanasaurus and more derived
sauropodomorphs): Character 311 (0 → 1), Charac-
ter 336 (0 → 1), Character 354 (0 → 1). Some trees:
Character 133 (0 → 1), Character 207 (2 → 1), Character
293 (0 → 1), Character 324 (0 → 1)
Node 69 (Sauropoda): Character 6 (0 → 1), Character 8
(2 → 3), Character 32 (0 → 1), Character 101 (0 → 1),
Character 157 (1 → 2), Character 167 (0 → 1), Character
183 (0 → 1), Character 212 (1 → 0), Character 214 (0
→
1), Character 233 (0 → 1), Character 280 (0 → 1),
Character 281 (0 → 1), Character 286 (0 → 1), Character
290 (0 → 1), Character 291 (0 → 1), Character 355 (0 →
1). Some trees: Character 177 (1 → 2)
Node 70 (Yannanosaurus + more derived
sauropodomorphs: Character 26 (1 → 0), Character
97 (1 → 0), Character 132 (0 → 1), Character 135 (0 →
1), Character 139 (1 → 0), Character 342 (0 → 1)
Node 71 (Barapasaurus + Patagosaurus): Character 162
(0 → 1), Character 166 (0 → 1). Some trees: Character 155
(1 → 0), Character 163 (0 → 1), Character 374 (0 → 1)
Node 72 (sauropods more derived than Vulcanodon): Char-
acter 170 (1 → 2). Some trees: Character 69 (0 → 1),
Character 95 (0 → 1), Character 119 (0 → 1), Character
199 (0 → 1), Character 259 (1 → 0), Character 266 (0 →
1), Character 294 (1 → 0), Character 298 (0 → 1), Char-
acter 300 (0 → 1), Character 342 (1 → 2), Character 346
(0 → 1)
Node 73 (Eusauropoda): Character 345 (0 → 1). Some
trees: Character 144 (1 → 2), Character 147 (0 → 1),
Character 155 (0 → 1), Character 164 (0 → 1), Character
170 (0 →
1), Character 171 (0 → 1), Character 187 (0
→ 1), Character 196 (0 → 1), Character 213 (1 → 0),
Character 254 (0 → 1), Character 299 (1 → 2), Character
315 (0 → 1), Character 330 (0 → 1)
Node 74 (sauropodomorphs more derived than Camelotia):
Character 144 (0 → 1)
Node 75 (Camelotia + more derived sauropodomorphs):
Character 353 (2 → 5)
Node 76 (Cetiosaurus + Neosauropoda): Character 129 (0
→ 1), Character 161 (0 → 1), Character 254 (1 → 2). Some
trees: Character 132 (0 → 1)
Node 77 (massospondylids more derived than
Massospondylus): Character 50 (0 → 1), Character
64 (0 → 1), Character 76 (0 → 1), Character 354 (0 → 1),
Character 357 (0 → 1)
Node 78 (Massospondylidae): Character 20 (0 → 1), Char-
acter 99 (0 → 1), Character 131 (1 → 2), Character 233 (0
→ 1), Character 318 (0 → 1), Character 349 (1 → 2)
Node 79 (Theropoda): Character 177 (0 → 1), Charac-
ter 257 (0 → 1), Character 360 (0 → 1), Character 371
(1 → 2). Some trees (in which Chindesaurus lies outside
Theropoda): Character 30 (1 → 0), Character 39 (0 → 1),
Character 256 (0/1 → 2), Character 364 (0 → 1), Char-
acter 365 (0 → 1), Character 366 (0 →
1), Character 367
(0 → 1)
Node 80 (Riojasauridae): Character 283 (0 → 1), Charac-
ter 284 (1 → 0), Character 289 (0 → 1), Character 295
(1 → 0)
Node 81 (Plateosaurus ingens + Plateosaurus engel-
hardti): Character 353 (3 → 4)
Node 82 (Plateosaurus): Character 107 (0 → 1)
Node 83 (Plateosauridae): Character 60 (0 → 1), Char-
acter 81 (0 → 1), Character 99 (0 → 1), Character 335
(1 → 0)
Node 84 (Guaibasauridae): Character 251 (2 → 1),
Character 255 (0 → 2), Character 376 (0 → 1). Some
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424 M. D. Ezcurra
trees: Character 178 (0 → 1), Character 201 (0 → 1),
Character 256 (0/1 → 2), Character 279 (1 → 0), Char-
acter 286 (1 → 0)
Node 85 (Herrerasauridae): Character 241 (0 → 1), Char-
acter 370 (0 → 1). Some trees: Character 103 (0 → 1),
Character 112 (1 → 0), Character 151 (0 → 1), Charac-
ter 167 (0 → 2), Character 174 (0 → 1), Character 180
(0 → 1), Character 183 (0 → 1), Character 189 (0 → 1),
Character 193 (0 → 1), Character 199 (0 → 1), Charac-
ter 201 (0 → 1), Character 256 (1 → 0), Character 265
(0 → 1)
Node 86 (Lufengosaurus + Glacialisaurus): Character 331
(0 → 1), Character 356 (1 → 2)
Node 87 (Mamenchisaurus + Omeisaurus): Character 121
(2 → 3), Character 131 (1 → 2), Character 133 (1 → 0),
Character 139 (0 → 1), Character 270 (1 → 0). Some trees:
Character 130 (0 → 1), Character 148 (0 → 1), Charac-
ter 197 (0 → 1), Character 296 (1 → 0), Character 305
(0 → 1)
Node 88 (Saturnaliinae): Character 258 (1 → 2),
Character 362 (0 → 1). Some trees: Character 215
(0 → 2), Character 353 (1
→ 0)
Supplementary material 4
Comments on Table 3 and Figure 19
Table 3 was performed to compare the dinosaur specific
diversity of the Ischigualasto Formation with that of other
main tetrapod groups of the unit, as well as with the dinosaur
diversity of typical Norian assemblages. The species of each
tetrapod group of each assemblage are detailed below.
In Figure 19 the specific diversity of the main tetra-
pod clades recorded in the lower third of the Ischigualasto
Fm. (NW Argentina), the lower Caturrita Fm. (SE Brazil),
and La Esquina Fauna of the Los Colorados Fm. (NW
Argentina) is depicted. This figure is based on the informa-
tion of Table 3. Although the Brazilian assemblage belongs
to a different basin, biostratigraphic correlations suggest
that the Ictidosaur Assemblage Zone of the Caturrita Fm. is
temporally close to the upper third of the Ischigualasto Fm.
(where fossil tetrapods are scarce) and the La Chilca Fauna
of the Los Colorados Fm. (lower levels) (Langer 2005b;
Langer et al. 2007a). This is suggested by the following
evidence: firstly, there are common components, such as the
dicynodont Jachaleria, in the Ictidosaur Assemblage Zone
of the Caturrita Fm. and La Chilca Fauna (lower levels)
of the Los Colorados Fm. (Langer 2005b). Secondly, the
Ictidosaur Zone of the Caturrita Fm. is stratigraphycally
directly above the “upper” Hyperodapedon Assemblage
Zone of the Santa Maria Fm., which can be correlated with
the middle of the Ischigualasto Fm., both characterized by
a decrease in the abundance of the rhynchosaur Hypero-
dapedon (in comparison with lower levels) and an abun-
dance of the cynodont Exaeretodon (Langer et al. 2007a).
La Esquina Fauna of the Los Colorados Fm. (upper levels)
was traditionally considered younger than the Ischigualasto
and the Caturrita fms. This correlation has been based
on the absence of Jachaleria, an abundant taxon in the
lower levels of the Los Colorados and Caturrita Fm., as
well as the numerical abundance of basal sauropodomorph
dinosaurs (Bonaparte 1982; Langer 2005b; Caselli et al.
2007) and the presence of neotheropods (Arcucci & Coria
2003; Ezcurra & Novas 2007b). Accordingly, the rich tetra-
pod fossil record of these three assemblages provides a
good basis for comparing tetrapod specific diversity along
the late Carnian-Norian time span.
Table 3 has been constructed on the basis of the following
information:
List of dinosaur and other tetrapod diversity in
Carnian and Norian outcrops
Ischigualasto Fm. (lower third of the formation: late
Carnian; Rogers et al. 1993; Furin et al. 2006)
Dinosauria (5)
Herrerasaurus ischigualastensis
Eoraptor lunensis
Chromogisaurus novasi
Panphagia protos
MACN-PV 18649a
Temnospondyli (2)
Pelorocephalus ischigualastensis
Promastodonsaurus bellmanni
Proterochampsidae (1)
Proterochampsa barrionuevoi
Crurotarsi (4)
Saurosuchus galilei
Aetosauroides scagliai
Sillosuchus longicervix
Trialestes romeri
Rhynchosauria (2)
Hyperodapedon sanjuanensis
Hyperodapedon mariensis
Procolophonidae (0)
Dicynodontia (1)
Ischigualastia jenseni
Cynodontia (5)
Exaeretodon frenguellii
Ischignathus sudamericanus
Ecteninion lunensis
Chiniquodon sanjuanensis
cf. Probainognathus sp.
Los Colorados Fm. (La Esquina Fauna: late Norian; Bona-
parte 1982; Caselli et al 2001)
Dinosauria (4)
Riojasaurus incertus
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Coloradisaurus brevis
Lessemsaurus sauropoides
Zupaysaurus rougieri
Temnospondyli (0)
Proterochampsidae (0)
Chelonia (1)
Paleochersis talampayensis
Crurotarsi (5)
Hemiprotosuchus leali
Pseudhesperosuchus jachaleri
Neoaetosauroides engaeus
Riojasuchus tennuisceps
Fasolasuchus tenax
Rhynchosauria (0)
Procolophonidae (0)
Dicynodontia (0)
Cynodontia (1)
Chaliminia musteloides
Lower Caturrita Fm. (early-middle Norian; Langer 2005a,
b; Langer et al. 2007a), non-dinosaurian dinosauromorphs
between brackets.
Dinosauria (2) [Dinosauromorpha (1)]
Unaysaurus tolentoi
Guibasaurus condelariensis
(Sacisaurus agudoensis)
Temnospondyli (0)
Proterochampsidae (0)
Crurotarsi (1)
Phytosauria indet.
Sphenodontia (1)
Clevosaurus riograndensis
Rhynchosauria (1)
Hyperodapedon sanjuanensis
Procolophonidae (1)
Soturnia caliodon
Dicynodontia (1)
Jachaleria candelariensis
Cynodontia (6)
Riograndia guaibensis
Brasilitherium riograndensis
Brasilodon quadrangularis
Irajatherium hernandezi
Charuodon tetracuspidatus
Exaeretodon riograndensis
Chinle Fm. (Petrified Forest Member: Norian; Long &
Murry 1995; Lucas et al. 1998; Irmis 2005; Irmis et al.
2007; Nesbitt et al. 2009), non-dinosaurian dinosauro-
morphs between brackets.
Dinosauria (3) [Dinosauromorpha (2)]
Coelophysoidea indet.
Chindesaurus bryansmalli
Tawa hallae
(Eucoelophysis baldwini)
(Dromomeron romeri)
Temnospondyli (1)
Apachesaurus gregorii
Proterochampsidae (0)
Crurotarsi (10)
Pseudopalatus pristinus
Pseudopalatus buceros
Pseudopalatus mccauleyi
Desmatosuchus smalli
Typothorax coccinarum
Rioarribasuchus chamaensis
Shuvosaurus inexpectatus
Postosuchus kirkpatricki
Hesperosuchus agilis
Revueltosaurus callenderi
Rhynchosauria (0)
Procolophonidae (0)
Dicynodontia (0)
Cynodontia (0)
Lower Elliot Fm. (Norian; Kitching & Raath 1984; Galton
& Van Heerden 1998; Olsen & Galton 1984; Gow &
Latimer 1999; Lucas & Hancox 2001)
Dinosauria (6)
Melanorosaurus readi
Euskelosaurus browni
Eucnemesaurus fortis
Plateosauravus
Antetonitrus ingenipes
Eocursor parvus
Temnospondyli (1)
Chigutisauridae indet.
Proterochampsidae (0)
Crurotarsi (1)
Basutodon
Rhynchosauria (0)
Procolophonidae (0)
Dicynodontia (0)
Cynodontia (2)
Elliotherium kersteni
Scalenodontoides macrodontes
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