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The fossil record of abelisauroid carnivorous dinosaurs was previously restricted to Cretaceous sediments of Gondwana and probably Europe. The discovery of an incomplete specimen of a new basal abelisauroid, Berberosaurus liassicus, gen. et sp. nov., is reported from the late Early Jurassic of Moroccan High Atlas Mountains. Phylogenetic analysis recovers Ceratosauroidea and Coelophysoidea as sister lineages within Ceratosauria, and Berberosaurus as a basal abelisauroid. Berberosaurus is the oldest known abelisauroid and extends the first appearance datum of this lineage by about 50 million years. The taxon bridges temporal, morphological, and phylogenetic gaps that have hitherto separated Triassic to Early Jurassic coelophysoids from Late Jurassic through Cretaceous ceratosauroids. The discovery of an African abelisauroid in the Early Jurassic confirms at least a Gondwanan distribution of this group long before the Cretaceous.
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2007
by
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AN ABELISAUROID (DINOSAURIA: THEROPODA) FROM THE EARLY JURASSIC OF THE
HIGH ATLAS MOUNTAINS, MOROCCO, AND THE RADIATION OF CERATOSAURS
ALLAIN, RONALDTYKOSKI,' NAJAT MICHEL MONBARON,
"
DALE
R
U
S
S
E
LL
,
"
and PHILIPPETAQUET
2
'Cadi University, Faculty of Sciences Semlalia, Department of Earth Sciences, Laboratory of Paleontology and
Biostratigraphy, B.P. 2390, 40000 Marrakech, Morocco,
de la Terre, Laboratoire de National Naturelle, UMR 8569 CNRS,
8 rue 75005 Paris, France,
'Museum of Nature Science, P.O. Box 151469, Dallas, Texas 75315
-
1469, U.S.A.,
of Energy and Mines, B.P.6 208 Rabat,Morocco;
de de Fribourg, Ch. du 4
,
CH
-
1700 Fribourg, Switzerland,
Carolina Museum of Natural Sciences, and Department of Marine, Earth and Atmospheric Sciences,
North Carolina State Box 8208, Raleigh, NC 27695, U.S.A.,
dale.russell@ncmail.net.
ABSTRACT
-
The fossil recorclof abelisauroiclcarnivorousclinosaurs was previously restricted to Cretaceous secliments
of and probably Europe.The of an incompletespecimen of
a
new basal
gen. et sp. nov.. is reported from the late Early Jurassic of Moroccan Atlas Mountains. Phylogenetic
analysis recovers Ceratosauroiclea ancl Coelophysoidea as sister lineages within Ceratosauria. and as
a
basal abelisauroicl. is the oldest known abelisauroiclancl extends the first appearance datum of this lineage
by
about
50
million years. The temporal.morphological.and phylogeneticgaps that have hitherto separated
Triassic to Early Jurassic coelophysoids from Late Jurassic through Cretaceous The discovery of an
African abelisauroicl in the Early Jurassic confirms
at
least
a
distribution of this group long before the
Cretaceous.
INTRODUCTION
Continentalstrata of late Early Jurassic age are rare, and little
is knownof dinosaur evolution around the Jurassic
boundary. There is almost no theropod record between the
Pliensbachian and the (ca. Ma) (Weishampel
et al., 2004). Thus, only four diagnosable theropod species have
been described from these stages: the coelophysoid
from the of Arizona (Camp, 1936;
Carrano et al., the enigmatic from
the
Sinemurian
-
Pliensbachian
of Antarctica (Hammer and
Hickerson, and the probable spinosauroids
nethercombensis
from the 1926,
and 1974) from the
of This lack of data is unfortunate because
hypotheses predict the diversification of some ma
-
jor saurischian clades Tetanurae, Neosauropoda) during
this interval (Wilson and 1998; 1999;
2002; Rauhut, 2003; and Barrett, 2005).
For
6
years, several expeditions have collected well
-
preserved
skeletal remains of dinosaurs from the late Early Jurassic
doute Series of the southern High Atlas Mountains in Morocco
et al., 2004; Montenat et al., 2005). Two bone
-
beds, re
-
lated to typical mud
-
flow deposition (Montenat et al.,
have yielded at least five partial skeletons of a primitive
dontid sauropod, (Allain et al., a
"
Correspondingauthor.
large carnivorous dinosaur of uncertain affinities, and a
sized theropod with ceratosaurian affinities. This article aims to
describe the latter, and determines its relationships
with other ceratosaurs (sensu Tykoski and Rowe, 2004) based in
part upon a recent and thorough cladistic analysis of this lineage
(Tykoski, 2005). The remains described here come from a single
area of about 4 m
2
, and is 100 m apart from the site that yielded
the holotypic specimen of Other remains of
including a long humerus have been found
near the bones of Further work in the
Series raises the possibility of new finds in this area.
Institutional
Naturelle de Marrakech. Morocco.
SYSTEMATIC PALEONTOLOGY
SAURISCHIA Seeley, 1887
THEROPODA Marsh, 1881
CERATOSAURIA Marsh, 1884 Rowe, 1989)
NEOCERATOSAURIA Novas, 1992 (sensu Holtz, 1994)
ABELISAUROIDEA 1991) Holtz, 1994
1998)
BERBEROSAURUS LIASSICUS,
gen. et
Holotype
-
Associated postcranial material housed in the
Naturelle de Marrakech, including a cervical
vertebra anterior part of the sacrum
the second left metacarpal (MHNM
-
Pt22); a right femur
(MHNM
-
Ptl9); the proximalend of the left tibia (MHNM
-
Pt21);
1
Published in "Journal of Vertebrate Paleontology 27(3): 610–624, 2007"
which should be cited to refer tothis work.
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the distal end of t he right tibia and t he left fibula
Referred Specimen
-
The proximal end of a right femur
Etymology
-
Generic name is from the Berbers who live
mainly in Morocco;
"
sauros
"
is Greek for lizard. Specific name
from Lias, referring to the statigraphic epoch of the specimen.
Type Locality
-
Douar of Tazouda, near the village of
doute in the Province of Ouarzazate, High Atlas of Morocco.
Horizon and Age
-
Upper bone
-
bed (
"
Fossil locality B
"
of
Allain et al., of the Toundoute continental series, middle
to late Early Jurassic
(Pliensbachian
-
Toarcian)
(Montenat et al.,
Diagnosis
-
Berberosaurusis characterized by the following
unique combination of charactersthat neststhe amongthe
abelisauroid ceratosaurs: highly pneumatic cervical vertebrae;
anteroposteriorly short cervical vertebral centra with
internal structure; cervical neural spine anteroposteriorly short;
ventral margin of sacral series strongly arched dorsally; trans
-
versely narrow sacral centra; proximal end of the second meta
-
carpal deeply grooved ventrally; femoral anterior trochanter
reaches proximally to mid
-
point of femoral head; large femoral
trochanteric shelf; tibia with subtriangular distal profile; pres
-
ence of an oblique ridge that proximally caps the medialsulcus of
the fibula. differs from in: short
cervicalcentra, pneumatic foramina on the cervical neural arch;
from in: structure of cervical vertebra,
low and short neural spine of th e cervical vertebra, femoral an
-
terior trochanter reaches proximally to mid
-
point of femoral
head; from in: absence of the
prezygapophyseal lamina on the cervical neural arches, short
cervical neural spine; from Abelisauria in: distal end of meta
-
carpalwith deepextensor pits; pronounced femoral trochanteric
shelf.
Jenny and colleauges (1980) and Taquet (1984) briefly re
-
ported another theropod from the late Early Jurassic of the
Moroccan High Atlas. This specimen comes from the Toarcian
Formation and is currently under preparation in the
National Naturelle, in Paris. It differs clearly
from Berberosaurus in its smaller size, the longer cervical verte
-
bral centra, and the absence of a sulcus on the medial surface of
the fibula.
DESCRIPTION
Cervical Vertebra
As with most of the holotypic material of the
recovered cervical vertebra was affected by tectonism. A fault
planein which gypsum recrystallized crosses t he vertebra length
-
wise, but the specimen is not deformed and its left side is well
preserved (Fig. 1). The distal tip of the
epipophysis complex and the ventral part of the posterior articu
-
lar surface are broken.The of this mid
-
cervicalvertebra
is short with a length less than 1.5 times the diameter of the
anterior articular surface (Table 1). The anterior surface is ver
-
tical and slightly concave, while the posterior articular surface
dips slightly posteroventrally (Fig. B). The damaged
teroventral area of the reveals at least two rounded
internal cavities separated by a thin septum. These cavities are
hereinterpreted as camerae. The ventral surface of the
is flat. The parapophyses are situated at the anteroventral corner
of the Two pairs of deep, ovoid pleurocoels invadethe
body of the vertebra (Fig.
D).
The anterior pleurocoels are
positioned dorsal t o th e parapophyses and excavate much of the
immediately behind the anterior articular surface.They
are longer than tall. There
is
at least one additional,
ventrallylocated foramen within the cervical anterior pleurocoel
FIGURE
1.
Cervical vertebra of
Berberosaurus
in left lateral
(A,
B),
left ventrolateral
(C,
D),
anterior
(E),
and posterior
views.
Abbreviations:
anterior centrodiapophyseal lamina;
accesory lamina;
apl,
anterior pleurocoel; camera; centro
-
postzygapophyseal lamina; lamina;
di,
di
-
apophysis; gypsum; interspinous ligament scar;
ne,
neural canal;
ns,
neural spine;
pcdl,
posterior centrodiapophyseal lamina;
pf,
pneu
-
matic foramen;
podl,
postzygodiapophyseal lamina;
posf,
postspinal
fossa;
poz,
postzygapophysis;
pp, ppl,
posterior pleurocoel;
prdl,
prezygodiapophyseal lamina; prezygapophysis;
se,
septum;
spol,
spinopostzygapophyseal lamina;
tpol,
intrapostzygapophyseal
lamina. Scale bar equals
1
cm.
that accesses the The posterior pleurocoel is as long as
tall. It is situated just below the suture between the and
the neural arch,
15
mm anterior t o the posterior articular surface.
Onceagain, at least one additional foramen pierces the posterior
wall of the pleurocoelous fossa (Fig. The additional pneu
-
matic foramina in botht he anterior and posterior pleurocoels are
unknown in other ceratosaurs, with the possible exception of
Dilophosaurm (Tykoski, 2005). They are consistent with the
structure described above (Britt, 1997; 2003).
The suture between the and neural arch is totally fused
and indiscernible. The cervical neural arch is nearly two times
taller than the and bears the marks of extensive
matization. Th e prezygapophyses overhang th e preceding
cal whereas the postzygapophysesdo not extend poste
-
riorly past the posterior articular surface of the The
four principal diapophyseal laminae present in saurischian ver
-
tebrae (anterior centrodiapophyseal lamina, posterior centro
-
diapophyseal lamina, prezygodiapophyseal lamina,
diapophyseal lamina) are present, in addition to the centro
-
2
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TABLE
1.
Measurementsof
Berberosaurus
gen et sp. nov.
Element Measurements
Cervical vertebra (MHNM
-
Pt9)
Length of
Posterior height of
Posterior width of
Anteroposterior length of the tip of the
neural spine
Sacrum (MHNM
-
Pt23)
Posterior width of of the first
sacral vertebra
Posterior height of of the first
sacral vertebra
Length of of the second sacral vertebra
Posterior width of of the second
sacral vertebra
Posterior height of of the second
sacral vertebra
Length of of the caudosacral
vertebra
Posterior width of of the first
caudosacral vertebra
Posterior height of of the first
caudosacral vertebra
Left metacarpal
Length
Proximal width
Distal width
Right femur
Length
Proximal width
Cicumference below the 4th trochanter
Distance from proximal end to top of
4th trochanter
Length of 4th trochanter
Right femur (MHNM
-
Tol
-
218)
Proximal width
Left tibia (MHNM
-
Pt16and MHNM
-
Pt21)
Cicumference below the crista
Distal width
Left fibula
Length width
length
Distal width
Distal length
prezygapophyseal,
centropostzygapophyseal,
physeal and intrapostzygapophyseallaminae(Wilson, 1999). The
diapophysis is directly dorsal t o the parapophysis. It is laterally
directed, ventrally pendant, and tapers distally (Fig. The
ventralsurface of the transverse process is perforated by a pneu
-
matic foramen as in and (Bonaparte
al., 1990; Carrano et al., The posterior wall of the fo
-
ramen is formed by a small accessory lamina (Fig. The
postzygodiapophyseal lamina is interrupted by a triangular
fossa20mmfrom the tip of the diapophysis(Fig. B), much as
in
Spinostropheus
et al., 2004). A wide
zygapophyseal fossa is present between the posterior centro
-
diapophyseal and the centropostzygapophyseal laminae (Fig.
Also as in
Spinostropheus,
a large foramen piercesthe floor
of the infrapostzygapophyseal fossa and opens into the neural
canal (Fig. There is a triangularfossa between the centro
-
postzygapophysealand intrapostzygapophyseal laminae, but it is
unknown if it is perforated by foramina as in
(Carrano et al., The neural spine is approximately cen
-
tered over the It is slightly damaged distally, but it is
anteroposteriorly short in comparisonto cervical neural spines of
coelophysoids and
Ceratosaum.
Posteriorly, within the large
postspinal fossa, the neural spine bears scars for interspinous
ligaments (Fig.
Sacrum
The partial sacral series is comprised of threefused centra with
very incomplete neural arches (Fig. 2). The total sacral count is
unknown. According to the positions of the preserved neural
arch and sacral rib, and the lack of a truesacral rib on the largest
of the specimen, the specimenis interpreted asthe first
sacral, the second sacral, and th efirst caudosacral vertebrae (Fig.
2). The centra are firmly fused to one another. The trace of a
suture is still visible between the centra of sacral 2 and
sacral 1, but is nearly eliminated between the centra of sacrals
1
and
2.
Although incomplete, the sacral series is strongly arched
dorsally (Fig. 2A) to the same degree as in and
(Gilmore, Bonaparte et al., The centra
are longer anteroposteriorly than tall dorsoventrally, and are
transverselyflattened
as
in abelisaurids and (Fig. 2B).
Metacarpal
The second left metacarpal was found near the fibula (Fig.
3).
It is considerably longer than the second metacarpal of the
2.
Sacrum of
Berberosaurus
(MHNM
-
Pt23) in left
lateral (A), ventral
(B),
and right lateral
(C)
views. Abbreviations: csl,
caudosacral vertebra 1; cstp, caudosacral transverse process; nc, neural
sl , sacral vertebra
1;
sacral vertebra 2; sacral rib 2. Scale
bar equals
5
3
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FIGURE
3.
Second left metacarpal of
in ventral (A), dorsal (B), and proximal (C) views.
Abbreviations: ventral concavity; Ia, metacarpal
I
articular surface.
Scale bar equals
2
cm.
lisaurid (Coria et al.,
2002).
The proximal end is
wider than the distal. It has an asymmetrical trapezoidal,proxi
-
mal end (Fig. with proximalcotyles separated ventrally by a
deep concavity (Fig. 3A). The medial cotyle is more developed
and expanded mediolaterally and ventrally. The contact area
between metacarpals I and is restricted to the medial surface
of the proximal base of the second metacarpal, unlike
anurans. The shaft of the metacarpal tapers distally. As observed
in distal view, the distal end is rotated about clockwise with
respect to the proximal end. It is deeply grooved and asymmetri
-
cal, with the medial condyle more proximally
-
situatedthan the
lateral (Fig. 3B).
Femur
The femur is the only element known from two specimens. A
nearly complete right femur was found associatedwith the other
bones described here (Fig. 4), and the proximal end of a right
femur from a smaller individual(Fig.
5)
was foundat the sitethat
yielded the holotypic material of Both femora
are hollow. The proximal end of the larger and better
-
preserved
femur was affected by tectonism and is now displaced
1
cm an
-
FIGURE
4.
Right femur of
Berberosaurus
in
anterior(A),medial (B),posterior (C),andlateral
(D)
views. Abbreviations:
atr, anterior trochanter; femoral head; great trochanter; mep, medial tibiofibular crest; ts , trochanteric shelf;
fourth trochanter. Scale bar equals
5
cm.
4
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FIGURE
5.
Proximal part of a right femur of
in posterior (A),and anterior (B) views. Abbreviations:
atr, anterior trochanter; femoral head; great trochanter;ts,
chanteric shelf. Scale bar equals
5
terolaterally. The shaft of the femur is sigmoid in anterior and
posterior views (Figs. 4A,
C),
and relatively straight in lateral
and medial views (Figs. D). Its cross
-
sectionis triangular at
the level of the fourth trochanter and more rounded above the
distal condyles. The femoral head is oriented anteromedially
(Fig. 4B) and distally (Fig. and the proximal femur narrows
anteroposteriorly toward t he greater trochanter as in other
tetanuran theropods. A shallow groove runs mediolaterally
across the middle of the proximal articular surface. The greater
trochanter is confluent with the femoral head. The posterior
surface of the proximal femur bears a well
-
defined
dially to distolaterally
-
trending across the femoral neck
(Fig. giving the femur a posteriorly hooked profile in proxi
-
mal view. The morphology of the anterior trochanter of
is difficultto assess. The anterior trochanter is almost
as stout as the spike
-
like version present in most coelophysoids,
but it is more mediolaterally compressed and flange
-
like as in
abelisaurids, and tetanurans. The
anterior trochanter extends proximally as far as the level of the
right
middle of the femoral head, and is set off from the femoral shaft
by a weak cleft. The holotypic femur shows more of a mound
than a shelf for the M. iliofemoralis insertion (Fig. 4). The re
-
ferred femur exhibits a pronounced trochanteric shelf that origi
-
nates on the anterior base of the anterior trochanter and extends
distolaterally as in coelophysoids, and
Ceratosaurus
(Fig.
5
A
-
B). This suggests some degree of femoral dimorphism in
as in
Coelophysis
(Colbert, 1989; Raath,
Ceratosaurus
et al., and (Carrano et
al., The fourth trochanter is strongly developed. It rises 19
mm above the posteromedial margin of the femur and extends
approximately one
-
fifth the length of the bone (Fig. 4 B
-
D) to
end 240 mm from the proximal articular surface. The holotypic
femur preserves an enlarged medial epicondyle (Fig. but
because its distal condyles are broken, it is impossible to know if
this enlargement was as strongly developed as in abelisauroids.
Tibia
The tibiae are badly damaged, with only a part of the proximal
left tibia (Figs. 6A
-
B) and the distal end of the right tibia pre
-
served (Figs. 6C
-
E). The proximal piece was affected by
The proximal articular surface is missing, but the distal
parts of th e fibular crest and the cnemial crest are preserved(Fig.
6A). The fibular crest is well developed both distally and later
-
ally and runs parallel to the main shaft axis (Fig. 6B). The
mial crest curves laterally and the tibia has a hooked profile in
proximal view. A nutrient foramen lies just posterodistalto the
distal end of the cnemial crest (Fig. 6B). The distal end of the
tibia is not fused with the astragalus despite the apparent matu
-
rity of the Moroccan specimen. The shaft of the tibia is thicker
mediallythan laterally (Fig. 6E). The distal end of the right tibia
is gently concave anteriorly and strongly convex posteriorly (Fig.
6E). The lateral margin bears a scarred contact surface for the
fibula. The lateral malleolus is broken distally. The oblique but
-
tressthat accommodated t he ascending process of the astragalus
slopes distomedially at about to the horizontal. The distal
tibia is mediolaterally expanded, and has a subtriangular outline
that contrastswith the more rectangular distal profile observed
in coelophysoids.
I
E
tfas
JRE 6. Tibiae of Proximal end of the left tibia in medial (A),and lateral (B) views; distal end of the
tibia in posterior
(C),
anterior
(D),
and
(E)
views. Abbreviations: crest; fc, fibular crest;fo, nutrient foramen;
tibial facet for ascending process of astragalus;tfas, tibial facet for astragalus tpvp, tibial posteroventral process. Scale bar equals
5
cm.
5
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Fibula
PHYLOGENETIC RELATIONSHIPS
The left fibula is complete (Fig.
7).
Its proximal end is
posteriorly expanded and bears a deep, proximodistallyelongate
sulcus on its medial surface. This sulcus opens posteriorly and is
capped proximally and anteriorly bya pronounced ridge that is
also present in coelophysoids and Ceratosaurus (Fig. This
ridge is raised from th e remainder of the medial surface and has
a rough texture. The shaft of the fibula tapers distally, except at
the level of the insertion of the M. iliofibularis,which is marked
by the presence of a large,
anterolaterally
-
projecting
process
(Fig. 7A). The distal end of the fibula is slightly expanded both
anteroposteriorly and mediolaterally. It is not co
-
ossified with
the ascending process of the astragalus. The distal fibula has an
anteromedialflange that may have partially overlapped the as
-
cending process of astragalus as in some coelophysoids and
tosaurus.
FIGURE
7.
Left fibula of Berberosaurus
in
lateral
(A),
and medial
(B)
views.
Abbreviations:
alp,anterolateral pro
-
cess;ffl, fibular flange; fibular sulcus;
ri,
ridge.Scale
bar
equals
5
cm.
Ontogenetic Status
Recognition of the ontogenetic stage of and
other taxa is criticalto proper comparisons and codingin
our phylogenetic analysis (Carrano et al., 2005; Tykoski, 2005).
Characterslikely to be expressed only in later stagesof ontogeny
were treated as missingdata in coelophysoidtaxa represented by
insufficientlymature specimens in our data matrix (see Tykoski
for more details on the ontogenetic status of these various
taxa).Three of the coelophysoidmaturity
-
dependent characters
listed by Tykoski (2005, Tab. 6) that were scored in
(see Appendix 2) were the absence of fusion between cervi
-
cal ribs and their respective vertebral centra (character no
co
-
ossification between the astragalus and tibia (character
and no co
-
ossifcationbetween the astragalus and fibula (charac
-
ter 242). Given the w
-
ossificationof these elements in relatively
mature specimens of both coelophysoids and ceratosauroids it
suggests that the holotype of may not be a fully
mature individual. Features that could reveal information re
-
gardingthe relative maturity of the specimeninclude: the sacral
centra exhibit full fusion to one another such that their sutures
are nearly indiscernible; the femoral anterior trochanter is a
diolaterally compressed flange
(
=
aliform process) projecting an
-
teriorly from t he bone; t he medial side of the proximalend of the
fibula is excavated by a longitudinal groove, and the latter is
overlapped by an oblique (posteroproximally to anterodistally
oriented) ridge; and the fibula bears a medial flange that over
-
laps part of the ascending process of t he astragalus. T he balance
of these observations suggests that the holotypic specimen of
is a that died prior to reaching skeletal
maturity. We also recognize that the quantitative ontogenetic
analysis wnducted by Tykoski
(2005)
focused strictly upon
physoid taxa, and we acknowledgethat Berberosaurusmayhave
had a different ontogenetic pattern than coelophysoids.
Methods
The phylogenetic position of the new was evaluated by
scoringfour Scutellosaums,
and and 30 taxa (Appendix 2) for 264
parsimony
-
informative characters (15 ordered, 249 unordered,
see Appendix 1) (Tykoski, 2005). The data matrix was analyzed
cladistically using (Swofford, Trees were
rooted using the method with taxa set as
successively paraphyletic taxa relative to the monophyletic
group. The analysis was conducted as a heuristic parsimony
analysis with branch swapping by simple addition using
the tree bisection
-
reconnection algorithm. A heuristic search was
chosen because of large number of taxa and characters made
more exhaustive search methods impractical.Multiple character
states within a single were treated as polymorphisms, as
originallyintended in the coding of the matrix.
Results
The analysis resulted in 21 equally most parsimonious hypoth
-
eses of phylogeny
(L
=
636, C.I.
=
.=
0.7289). A
traditional Ceratosauria (including Coelophysoidea and
sauroidea) was recovered as the sister stem
-
lineage to
rae. The 21 trees differed only in the positions of the
and the informally named
"
Shake
-
N
-
Bake
"
Berberosauruswas weakly supported as
an abelisauroid more derived than but outside a
+
Abelisauria clade in all the recovered trees
(Fig.
8,
see Appendix 3 for the distribution of unambiguous
napomorphiesat each node of the strict consensus tree).
6
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FIGURE
8.
Phylogenetic relationships of
within Theropoda. Strict consensus tree of 21 most parsimonious trees
(L
=
636,
C.I.
=
0.4890,
R.I.
=
0.7289).
Clade numbers:
1,
Theropoda;
2,
Neotheropoda;
3,
Tetanurae;
4,
Avetheropoda;
5,
Spinosauroidea; 6,
Ceratosauria;
7,
8,
Coelophysidae;
9,
Ceratosauroidea;
10,
Neoceratosauria;
11,
Abelisauroidea.
DISCUSSION
The discovery of in late Early Jurassic sedi
-
ments of Morocco has substantial phylogenetic and
geographic implications. Recent cladistic analyses of basal
Theropoda have differed over whether the coelophysoid
lineage was a member of Ceratosauria (Rowe, 1989;
1999; Tykoski and Rowe, Tykoski, or was outside
the clade (Carrano and Sampson,1999;
Forster,1999; Sampson et al., 2001; Carrano et al., Rauhut,
2003; et al., Critics of a 'traditional' Ceratosauria
(including coelophysoids) pointed to the large stratigraphic gap
between the youngest coelophysoids
(Pliensbachian
-
Toarcian)
and oldest 'true' ceratosaurs (Kimmeridgian
-
Tithonian), and
suggested that there is less of a stratigraphic gap when
sauroids are linked with tetanurans than when they are linked
with coelophysoids.Our cladistic analysis recovers a traditional,
monophyletic Ceratosauria (Rowe, 1989) and places
as an abelisauroid more derived than the basal
tosaur from the Late Jurassic, and the abelisauroid
of Early Cretaceous age(Fig. 9; see Appendix
4
for phylogenetic definitions used here). Derived characters
sharedwith other ceratosaurians include posteriorpleurocoelsin
post
-
axial cervical centra, sacral centra exhibiting full fusion to
one another such that sutures are nearly indiscernible by adult
-
hood, and a proximal end of the fibula with an oblique ridge that
overlaps the proximal part of the medial fibular groove (Appen
-
dix
3).
Abelisauroid features present in include
the lateral surface of post
-
axial cervical arch pedicels pierced by
foramina to the postzygapophysis, post
-
axial cer
-
vical neural arches with pneumaticcavities lateral to the neural
canal, and cervical neural arch surfaces ventral to transverse
processes pierced by multiple pneumatic foramina.
Bevbevosaurus
is the oldest known abelisauroid, and it repre
-
sents a considerable temporal range extension for a lineage
whose other members are Neocomian et al., or
younger (Tykoski and Rowe, except if the material from
Tendaguru, recently described by Rauhut is proved by a
future phylogenetic analysis to be an abelisauroid. Its presence
implies a previously unrecognized diversification of
roids by the Early Jurassic (Fig. 9).
Bevbevosaurus
essentially
closes the stratigraphic gap separating coelophysoids and
tosauroids, as predicted by cladistic phylogenetic hypothesis.
Abelisauroids, and more especially Abelisauridae were used as
key evidence for faunal exchanges between Gondwanan land
-
masses (Sampson et al., 1998; et al., and between
FIGURE
9.
Stratigraphically calibrated phylogeny of Ceratosauria and basal Theropoda, based on the strict consensus tree of the current study.
Clade numbers:
1,
Theropoda;
2,
Neotheropoda;
3,
Tetanurae;
4,
Ceratosauria;
5,
Ceratosauroidea; 6, Neoceratosauria;
7,
Abelisauroidea;
8,
Arcs
indicate stem
-
names,solid circles indicate node
-
names. Black lines indicate known stratigraphic ranges and grey lines indicate
inferred ghost lineages.
7
http://doc.rero.ch
Gondwana and Europe et al., 1988; Loeuff,
because their record was restricted to Late Cretaceous strata of
the southern continents and probably Europe (Weishampel et
al., 2004). reveals that basal abelisauroids were
already diversified by the Early Jurassic, and they were probably
distributed between Africa, South America, Madagascar, India
andEuropelong before the Cretaceous and t hefragmentation of
Gondwana.Thisscenario is consistent with the pan
-
Gondwanan
hypothesis suggested by previous authors et al.,
et al., but with faunal exchanges among
Gondwanan landmasses occurring between the Early Jurassic
and the Early Cretaceous. It also suggests that fossils of basal
abelisauroids should be present in Early Jurassic sediments
across Pangea,given that Laurasia and Gondwana werestill con
-
nected through that time. This discovery emphasizeshow poorly
known is the origin and early evolution of ceratosauroids, and
highlights the importance of finding and describing new Early
and Middle Jurassic theropod remains in order to document the
evolutionary history of Theropoda across the Triassic
-
Jurassic
faunal transition.
ACKNOWLEDGMENTS
Thiswork was supported by the Ministryof Energy and Mines
of Morocco,the Committee for Research and Exploration of th e
National Geographic Society (Grant the Agence
versitaire de la Francophonie and t he Fondation des Treilles. We
thank R. Vacant and
P.
Richir for helping to the preparation of
the material,P. for photographs, J. Wilson and
K.
Padian
for their critical and helpful comments, and all the participants
in the Project: P. Richir, M. Rouchdy,
C.
Montenat,
M. A. Faskaoune,M. Fontaine,S. S. Ladeveze,
A. Aumont,
C.
and the students from Marrakech Uni
-
versity.
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APPENDIX 1. of characters used in phylogenetic analysis.
Characters ordered by anatomical region. UO: unordered multistate
character;0 : ordered multistate character.
1. Craniofacial bones maxilla, jugal, quadratojugal, nasal) rela
-
tively smooth (0), or sculptured (1) (Novas, 1997).
2. Skull length times (0), or times (1) posterior height
(height
=
articular condyle of quadrate to dorsal
-
most edge of
parietal) (Forster, 1999;
3. Orbit approximately circular (0), or keyhole
-
shaped,with narrower
ventral end (1) (Gauthier, 1986).
4. Orbit anteroposterior diameter or internal antorbital
nestra length (Holtz 1998).
5. Internal antorbital fenestra anteroposterior length or
maximum skull length (Rowe, 1989).
6. Premaxilla body (excludes maxillary and nasal processes) height1
length ratio or (1) (modified from Holtz 1994,1998;
Sampson et al., 1998; Carrano et al., 2002).
7. Premaxilla lateral surface penetrated by many neurovascular fo
-
ramina (0), or few or none (1).
8. Premaxilla nasal process comprises or (1) of ex
-
ternal naris anterodorsal border (Holtz, 1998).
9. Premaxillary tooth row terminates ventral to (0), or entirely ante
-
rior to (1) external naris
10. Premaxillary lateral surface dorsal to second tooth position smooth
(0), or marked by small pit at base of nasal process (1).
11.
Maxillary process of premaxilla dorsoventrallywide and plate
-
like
(0),or narrow and rod
-
like (modified from Gauthier,1986; Rauhut,
2003).
12. Maxillary process of premaxilla contacts nasal (0), or does not con
-
tact nasal, allowingmaxilla t o contribute to
rim
of externalnaris (1)
(modified from Gauthier, 1986; Holtz,1998; Rauhut,
13. Maxillary process of premaxilla anteroposterior length or
much length of alveolar body of premaxilla (modified from
Holtz,1998).
14. process of premaxilla ventral margin (0), or
with directed flange, resulting in appearance of
"
forked
"
premaxilla (1) (Rauhut, 2003).
15. Palatalprocess of premaxilla a pronouncedshelf (0), or only a blunt
ridge or absent (1) (Sampson et al., 1998).
16. Premaxilla and maxilla with strong, immobile articulation (0), or
are only loosely articulated with each other (1)
17. Premaxilla and maxilla in contact at alveolarmargins (0), or alveo
-
lar margins do not contact (1).
18. Premaxilla
-
maxillasuture uninterrupted (0), or interrupted by
foramen (1) (Gauthier 1986,Novas,1992; e t al., 1993;
Coria and Salgado, 1998).
19. Anterodorsal margin of is linear or anterodorsally convex
(0), or anterodorsally concave (1) in lateral view (modified from
Holtz,1998).
20. Transition along dorsal border of maxilla from anterior process to
dorsal process is gradual,smoothly curved (0),or abrupt to angular
(1) in lateral view.
21. Dorsal process of maxilla axis angles posterodorsally between
and or or (2) from horizontal. (UO)
22. Dorsal process of maxilla long and contacts lacrimal (0), or
with
very short posterior component that does not contact lacrimal (1)
(Coria et al.,
23. Anterior process of maxilla length 510% or 10% or
225% (2) total length. (UO)
24. Ratio of dorsoventral height of proximal end of anterior processof
maxilla versus height of alveolar of maxilla at first alveolus
posterior to rim of internal antorbital fenestra (0), or 21.0 (1).
25. Anterior tip of alveolar margin oriented approximately
horizontal(0), or curves sharply mediodorsally (1) (modified from
Rowe, 1989).
26. Maxillary first alveolus opens ventrally (0), or anteroventrally (1)
(Rowe,1989).
27. Maxilla with or 220 (1) in adults.
28. Maxilla with teethlalveoli in adults (modified from
Carrano et al., 2002).
29. Maxillary tooth rowends posterior or ventral (0), or anterior (1) to
anterior
rim
of orbit (Gauthier 1986).
30. Ventral marginof maxillary antorbitalfossa o r marked by
low rounded ridge (0), or sharply marked by alveolar ridge that
parallels alveolar margin (1).
31. Maxillary antorbital fossa anterior to internal antorbital fenestra
broad (0), or narrow, extends little beyond
rim
of internal antorbital
fenestra (1) et al., 1994; Forster, 1999).
32. Anterior margin of maxillary antorbital fossa rounded (0), or
squared, with angular corners and nearly straight anterior border
(1) (Rauhut, 2003).
33. Maxillary antorbital fossa ventral to internal antorbital fenestra
broad (0), or very narrow or obscured in lateral view (1) (Novas
1989; Carrano et al., 2002).
34. Promaxillaryfenestra of maxilla absent (0), or present, clearly vis
-
ible in lateral view or present and concealed from lateral view
by lateral lamina of maxillary antorbital fossa (2) (modified from
Holtz, 1994,1998). ( 0 )
35. Medial lamina of dorsal process of maxilla smooth and continuous
(0), or with deep accessory pneumatic excavation (1) (Carrano et
al.,
36. Medial lamina of maxillary antorbital fossa solid (0), or perforated
by maxillary fenestra (1) (Gauthier, 1986).
37. process of maxilla short, protrudes little be
-
yond maxilla's anterior process (0), or is long, finger
-
likeprojection
or long, dorsoventrally tall, mediolaterally narrow, and plate
-
like (2). (UO)
38. Medial surface of anteromedial process of maxilla smooth (0), or
bears longitudinal ridges (1) et al., 1998).
39. Nasals are separate (0), or partiallyfused, either at anterior end or
median crests or prominences o rfused over entire length
(2) in adults (modified from (0)
40. Lateral margin of nasalsimple (0),or bearslowexpanded ridge
or forms part of parasagittalcrest from dorsolateral margin of
skull or forms all of thin parasagittal crest (3) (modified from
Holtz,1998).
41. Dorsal surfaces of nasals relatively smooth (0), or rugose, with
heavy pitting and sculpturing (1) (Holtz,1998).
42. Lateral or posterolateral surface of nasalsolid (0), or perforated by
pneumatic (1) (Forster,1999).
43. Lateral surface of anterior end of nasal along margin of external
naris relatively flat or with concave fossa or with laterally
convex hood covering posterior part of external naris (2) (Carrano
et al., 2002). (UO)
44. Nasal excluded from (0), or contributes to border of (1) antorbital
cavity (Holtz,1998).
9
http://doc.rero.ch
45. Frontals anteroposteriorly short and approximately rectangular (0),
or elongated and triangular (1) in dorsal view (Holtz,1994).
Frontals remain separate (0), or indistinguishably fuse t o each other
(1) in adults (Holtz, 1998).
47. Frontals relativelyflat or contribute to dorsal skull roof promi
-
nences horns, knobs, bosses) or bear large, laterally posi
-
tioned supraorbital horns (2) et al., 2002). ( 0)
48.
Frontals and parietals remain separate (0), or fuse (1) in adults
(Holtz,1998; Forster, 1999;
49. Frontal
-
parietal contact area relativelyflat (0), or with median fossa
in saddle
-
shaped depression (1) (Sampson et al., 1998).
50. Dorsal surface of parietal relatively flat (0), or with transversely
thickened sagittal crest between supratemporal fenestrae (1) (No
-
vas,1989; Holtz,1998).
51. Parietal nuchal crest relatively small, thin (0), or greatly enlarged
and elevated (1) (Forster, 1999;
52. Lacrimal blocky or triangular (0), or an inverted L
-
shape (1) in
lateral view (modified from Rauhut, 2003).
53. Lacrimaldorsoventrallyshorter than orbit and fails to reachlevelof
orbit's ventral rim or as tall or to height of orbit with
ventral end that reach level of orbit's ventral rim(1) (modified from
Rauhut, 2003).
54. Anterior of lacrimal dorsoventral height approximately
equal (0), or much narrower (1) than anteroposterior width of ven
-
tral of lacrimal et al., 1996).
55. Ratio of lacrimal anterior lengthversus ventral length
0.65 or or (2) et al., 1996). (UO)
56. Lacrimaldoes not contact postorbital (0),or bears posterior process
that contacts postorbital, excludingfrontal from rim of orbit: absent
(1) (Sampson et al.,1998).
57. Lacrimal antorbital fossa without (0), or with (1) deep pneumatic
recesses in posterodorsal corner of lacrimal (Novas, 1989; Holtz,
1998).
58. Lateral lamina of lacrimal ventral linear and remains poste
-
rior to medial lamina (0), or sinuous and protrudes anteriorly be
-
yond medial lamina (1).
59. Lacrimal antorbital fossa small or nonexistent (0), or large, exca
-
vates laterally open triangular fossa on lacrimal ventral (1).
60. Lacrimal not dorsally enlarged (0), or with distinct
"
horn
"
terodorsal boss or blade) (1) (Rauhut, 2003).
61. Lacrimalventral process with relatively linear orbital margin(0), or
with suborbital convexity (1) (Sampson et al.,
1998).
62. Postorbital long
-
axis oriented nearly vertical (0), or anteroventral
-
posterodorsal (1) (Novas, 1989, Carrano et al., 2002).
63. Ventral process of postorbital nearly linear or slightly
curved (0), or
with
distinct suborbital process (1) (Gauthier, 1986,
Holtz,1998).
64. Ventral process of postorbital transversely narrow with
triangularcrosssection (0), or broadwith U
-
shaped cross
-
section (1)
et al., 1994).
65. Postorbital with stepped
-
down ventrolateral fossa: absent (0), or
present (1) (Sampson et al., 1998, Carrano et al., 2002).
66. Anterior process of postorbital dorsally higher than posterior pro
-
cess (0), or at about same level as posterior process, resulting in
T
-
shaped postorbital (1) 1995; Holtz,1998).
67. Jugal
-
maxilla overlap length or (1) total jugal
length (Sampson et al.,1998).
68. Anterior process of jugal abuts lacrimal (0), or bears dorsal flange
that laterally overlaps ventral process of lacrimal (1) (modified
from et. al., Carrano et al., 2002).
69. contacts internal antorbital fenestra (0), or does not contact
internal antorbital fenestra, participates in external antorbital
nestra or no participation in external antorbital fenestra (2)
(Holtz,1998; Carrano et al., (UO)
70. Posterior process of jugal undivided (0), or divided, ventral prong
or much shorter than dorsal prong or divided with
ventral prong much longer than dorsal prong (2) (modified from
Gauthier,1986; a nd Novas, 1993; et al., 1993;Holtz,
1998). (0 )
71. Lateral surface of jugal flat (0), or with low rounded ridge that
traverses anterior and posterior processes (1) and
72. Ventral process of squamosal narrow(0), or broad expanded
(1) (Rauhut, 2003).
73. Quadratojugal and squamosal contact small (0), or broad or
absent (2) (modified from Holtz, 1998; Rauhut 2000,2003). (UO)
74. Quadratojugal and quadrate remain separate (0), or fuse (1) in
adults (Holtz, 1994, 1998).
75. Quadrate short or moderately tall and dorsoventrally oriented (0),
or tall and posteroventrally angled so ventral is posterior to
dorsal condyle and paraoccipital processes (1) (modified from
Rauhut, 2003).
76. Quadrate foramensmall and surrounded mostly by quadrate (0), or
absent or large and surrounded by near equal shares of
quadrate and (modifiedfrom Novas,1989; Holtz,
Carrano et al., 2002; Rauhut, 2003). (UO)
77.
Supratemporal fossae widely separated by parietals (0), or in
tact posteriorly but separated anteriorly by triangular plate of
rietals or confluent so parietals reduced to a sagittal crest (2)
(modified from Rauhut, 2003). (UO)
78. lateral surface not excavated by fossa (0), or exca
-
vated by anterior tympanic recess (1) (Rauhut, 2003).
79. Basisphenoidal recess very shallow, poorly developed, or absent
(0), or deep and well developed (1) (Rauhut, 2003).
80. Transverse intertuberal lamina of basisphenoid a simple wall (0),or
bears small median spur that projects anteriorly along roof of
basisphenoidal recess (1).
81. Cranial nerves X and XI exit skull laterally through
(=jugular) fissure or through on posterior
skull surface lateral to occipital condyle and foramen for cranial
nerve (1) (Rauhut, 2003).
82. Ventral edge of proximal end of paroccipitalprocess is dorsal to (0),
or at same levelor ventral t o (1) horizontal plane through middleof
occipital condyle (modified from Rauhut, 2003).
83. Interorbital braincase elements interorbital septum or
orbitosphenoid, sphenethmoid) do not ossify (0), or ossify (1)
by adulthood (Novas,1997; Carrano et al., 2002).
84. Ectopterygoidflange of pterygoid flat or marked by fossa (1)
(Gauthier.
,
,
85. ventral surface flat (0), or with deepfossa or with
fossaand groove excavated into body of element from medial
side (2) (modified from Rauhut, 2003). (
UO
)
86. Dorsal edge of anterior tip of dentary wntinuouswith mid
-
dentary
(0), or is raised conspicuously relativeto middle and posterior parts
of dentary (1)
87. Dentary tooth count (0), or (1) (Carrano et al., 2002).
88. Posterodorsal end of dentary without (0), or with (1) socket for
surangular prong (Carrano et al.,
89. Posteroventral process of dentary extends further posteriorly than
posterodorsal process (0), or in length to posterodorsal
process (1)
90. External mandibular fenestra small or moderate in size (0),or very
large (1) (Gauthier, 1986;Sampson et al., 1998).
91. Splenial without (0), or with (1) foramen (either closedor ventrally
open) near anteroventral margin (Rauhut, 2003).
92. Splenial posterior margin forked (0), or straight, not forked (1)
(Rauhut, 2003).
93. Angular stops short of posterior end of mandible (0), or reaches
posterior end of mandible, blocking surangular from ventral margin
of jaw in lateral view (1).
94. Retroarticular process of mandible about same mediolateral width
(0), or much broader (1) than mandible anterior to jaw joint
(Rauhut, 2003).
95. Serrations on mesial
-
most premaxillary teeth of 'normal' size and
number (0), or are very small and few in number, or wholly lacking
(1) (Rowe,1989; Rowe and Gauthier, 1990).
96. Mesial premaxillary teeth cross
-
section labiolingually flattened (0),
or subcircular (1) or asymmetrical, (2) (Rowe, 1989).
97. axis of mesial premaxillary teeth (0), or nearly
straight (1) (Rowe,1989).
98. Maxillary interdental plates remain separate (0), or fuse to each
other (1) (Rauhut, 1995; Holtz,1998).
99. Medial surfaces of maxillary interdental plates smooth (0), or
heavily (1) (Sampson et al., 1996, 1998).
100. Maxillary interdental plates relatively tall, broadly exposed (0), or
low and partially obscured by lamina of maxilla (1) in medial view
(modified from et al., 2002).
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101. Mesial dentary teeth similar in size (0), or enlarged (1) relative to
mid
-
and distal dentary teeth (Rauhut, 2003).
102. Anterior articular surfaces of cervicaland anterior dorsal centra flat
or weakly concave (0), or strongly convex, ball
-
like (1) (Gauthier,
1986).
103. Posterior articular surfaces of cervical and anterior dorsal centra
flat or weakly concave (0), or deeply concave (1) (Gauthier,1986).
104. Anterior articular surfaces of anterior cervical centra circular or
taller than wide (0), or wider than tall (1) (Gauthier, 1986;Rauhut,
2003).
105. Post
-
axial cervical vertebrae without (0), or with (1) pleurocoels in
anterior part of (modified from Gauthier 1986; Rowe,
1989; Rowe and Gauthier, 1990).
106. Post
-
axial cervical vertebrae without (0), or with (1) pleurocoels in
posterior part of (modied from Gauthier 1986; Rowe,
1989; Rowe and Gauthier, 1990).
107. Cervical pleurocoels absent (0), or present as deep ovoid fossae or
pockets or present as foramina leading to internal
cavities (2). (UO)
108. Internal pneumatic cavities in vertebral centra absent (0), or pres
-
ent with structure or present with camellate structure
(2) (Carrano et al., 2002). (UO)
109. Transverseprocesses of postaxial presacral vertebrae without ven
-
tral braces (0), or ventrally braced by centrodiapophyseallaminae
110. Cervical epipophyses absent (0), or are lowridges or elongate,
narrow, and project posterolaterally beyond postzygapophyses
or strongly developed, and project mostly dorsally above
zygapophyses (3) (Holtz,1994,1998; Novas, 1997). (UO)
111. Cervical epipophyses not anteriorly expanded (0), or with anteri
-
orly directed processes (1) Carrano et al. 2002).
112. Cervical epipophyses at level below o r evenwith top of neural spine
(0), or dorsalto top of neuralspine (1) (modified from Holtz, 1998).
113. Cervical vertebrae without (0), or with (1)
prezygapophyseal laminae (Coria and Salgado, 1998).
114.
Axis
lacks pleurocoels (0), or bears pleurocoels (1) (Rowe, 1989).
115.
Axis
bearsa distinct diapophysis (0), or lacks a distinct diapophysis
(1) (Rowe,1989).
116. Axial parapophysis distinct, strongly developed (0), or weakly de
-
veloped to (1) (Rowe, 1989).
117. Axial neural spine and connected
by laminae (0), or widely separated (1) (modified from et
al., 2004).
118. Anterodorsal border of axial neural spine straight
-
edgedor weakly
concave (0), or dorsally convex and blade
-
like (1) (Makovickyand
Sues,1998).
119. Axial neural spine stops posterior to prezygapophyses (0), or ex
-
tends anteriorly beyond prezygapophyses (1).
120. Axial neural arch lacks pneumatic foramina (0), or with pneumatic
posterodorsal to diapophysis (1).
121. Anterior post
-
axial cervical centra with rounded or flattened ven
-
tral surface (0), or median ventral keel (1) (Makovicky, 1995;
Rauhut, 2003).
122. Post
-
axial cervical prespinal fossae narrow (0), or broad (1) (Coria
and Salgado, 1998).
123. Neural spines of post
-
axial dorsoventrallyhigh (0), or low
(1) (Russell and Dong, 1993; Carrano et al., 2002).
124. Neural spines of post
-
axial cervicals anteroposteriorly broad (0), or
very short (1) (Carrano et al., 2002).
125. Cervical zygapophyses positioned near midline (0), or displaced far
laterally away from (1) in dorsal view (Makovicky and
Sues,1998; Holtz, 1998).
126. Post
-
axial cervical neural arches solid (0), or house pneumatic cavi
-
ties lateral to neural canal (1).
127. Lateral surface of post
-
axial cervical arch pedicels solid (0), or
pierced by anteroventral to postzygapophysis
or bear triangular, posterior
-
directed apertures anterior to
postzygapophysis (2). (UO)
128. Mid
-
cervical length times (0), or 3 times or 2 4
times (2) diameter of anterior face (modified from Holtz, 1998;
(0)
129. Cervical neural spines approximately centered over (0), or
positionedmostly over anterior half of (1) (Carrano et al.,
2002).
130. Cervical ribs remain separate from (0), or co
-
ossify to (1) their
respective vertebral centra in adults (Gauthier, 1986).
131. Cervical ribs stout, relatively blade
-
like or exceptionally
thin
posteriorly (styliform) (1) (Holtz 1998).
132. Cervical ribs or (1) times length (Holtz 1998).
133. Cervical rib heads without signs of (0), or are marked
by pneumaticexcavations (1) (Harris,1998; Carrano et al., 2002).
134. Anterior cervicalrib shafts proximal part rod
-
like or blade
-
like
or greatly expanded and flattened (1) (Coria and Salgado, 1998).
135. Cervical and dorsal neural arch surfaces ventral to transverse pro
-
cesses are imperforate (0), or pierced by multiple pneumatic fo
-
ramina (1).
136. Anterior dorsal vertebrae without (0), or with (1) pleurocoel in
anterior of (Holtz, 1994,1998).
137. Dorsal vertebrae with parapophyseson or close to (0), or
with
parapophysesthat projectlaterally on
"
stalks
"
(1) (Carrano et
al.,
138. articulations absent (0), or present (1) on
dorsal vertebrae (Gauthier, 1986).
139. Dorsal transverse processes directed laterally, giving rectangular
profile in dorsalview (0), or with strongly backswept anterior mar
-
gin resulting in triangular profile in dorsal view (1) (modified from
Rowe, 1989; Rowe and Gauthier, 1990).
140. Transverse processes of dorsal vertebrae anterposteriorly narrow
(0), or broad, extending to lateral margin of prezygapophysis (1)
(modified from Rowe, 1989; Rowe and Gauthier, 1990).
141. Posterior dorsal vertebral length or 21.33 (1)
times height of anterior articular surface (modied from Rauhut,
2003).
142. Posterior dorsal vertebral length or 2 2 (1) times
height of anterior articular surface
143. Neural spines of posterior dorsal vertebrae no taller than
posteriorly long (0), or substantially taller than anteroposteriorly
long (1) (Rauhut, 2003).
144. Vertebra 23 part of dorsal vertebral series (0), or incorporated into
sacral series (as (1).
145. Vertebra 24 part of dorsal vertebral series (0), or incorporated into
sacral series (as (1).
146. Vertebra 25 part of dorsal vertebral series (0), or incorporated into
sacral series (as dorsosacral 1) (1).
147. Vertebra
28
part of caudal vertebral series (0), or incorporated into
sacral series
(
as caudosacral1) (1).
148. Ventral margin of sacral series relatively straight (0), or exhibits
strong dorsal
-
ward arching (1) (Holtz,1994, 1998;
149. Diameter of mid
-
sacralcentra approximately the same (0), or sub
-
stantially smaller (1) than posterior dorsals and anterior caudals
(Holtz,1994, 1998).
150. Sacral centra remain separate or exhibit co
-
ossification
or exhibit full fusion to one another so sutures nearly indiscernible
(1) by adulthood (modificationof Rowe,1989; Rowe and Gauthier,
1990).
151. Sacral neural arch elements (transverse processes, arches, neural
spines) and sacral ribsof adjacent vertebrae remain separate (0), or
fuse to one another by adulthood (1) (Rowe, 1989; Rowe and
Gauthier, 1990).
152. Sacral transverse processof at least mid
-
sacralsremain separate (0),
or coalesce to form nearly continuous horizontal sheet in dorsal
view (1) by adulthood (Rauhut, 2003).
153. Sacralribs and transverse processes remain separate (0), or fuse to
ilia (1) in adults (Rowe 1989; Rowe and Gauthier, 1990).
154. Ventral surface of caudal centra smooth or bear shallow longitudi
-
nal groove (0), or bear narrow, sharp longitudinal groove (1) (Rowe
and Gauthier, 1990).
155. Distal ends of transverseprocesses of anterior caudal vertebrae not
expanded (0), or anteroposteriorly expanded (1) (Coria and
gado,1998).
156. Hyposphene
-
hypantrum articulations absent (0), or present (1) on
anterior and midcaudal vertebral arches (Coria et al., 2002).
157. Neural spines of mid
-
caudal vertebrae rod
-
like and posteriorly in
-
clined (0), or tall, rod
-
like, and vertically directed (1) (Rauhut,
2003).
158. Neural arch elements (transverse processes, neural spines) not
abruptly reduced in caudal series (0), or reduced in distal caudal
vertebrae or reduced in mid
-
caudal vertebrae (2) (modified
from Gauthier, 1986).
(0)
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159. Distal caudal vertebral
with
overlap (0), or
overlap or 250% overlap (2) of preceding
(modified from Gauthier, 1986; Holtz, Rauhut, 2003). (0 )
160. Mid and distal haemal arches (chevrons) rod
-
lie or slightly ex
-
panded distally (@),or Gshaped (1) in lateral view (Carrano et al.,
2002).
161. Anterior processes on proximal end of haemal arches (chevrons)
absent (0), or smalltubercules o r large and projecting (2)
rano et al., 2002). (UO)
162. (=median fusion of clavicles) absent (0), or present (1)
(Holtz, 1994,1998).
163. Scapular blade broad and relativelyshort, ratio of maximum
minimum breadth or blade narrow and long, ratio of maxi
-
mum breadth 210 (1) (modified from Gauthier,
1986; Holtz,1994; Rauhut, 2003).
164. Distal end of scapular blade markedly expanded (0), or not ex
-
panded (1) and Zhao, 1993; Carrano et al., 2002).
165. Posterior margin of scapular blade curves over full length (0), or
nearly straight over most of length, curves posteriorlyonly at distal
tip (1).
166. Anterodorsal border of acromion process of scapula protrudes con
-
spicuously (@),or has smooth, continuous, high
-
angle transition to
scapular blade (1) (modified from Rauhut, 2003).
167. Anterior margin of scapulocoracoid at scapula
-
coracoid contact
notched (0), or continuous and uninterrupted (1) in adults (Holtz,
1998).
168. Posteroventral process of not expanded beyond glenoid
fossa (0), or expanded beyond margin of glenoid fossa (1)
et al., 1996).
169. Humerus length (0), or (1) femur length (Novas, 1993).
170. Humerus proximal head flattened (0), or rounded, bulbous,
spherical(1) (Holtz, Rauhut, 2000).
171. Humerus with anteroposterior sigmoid curvature (0), or is straight
(1) in lateral view Rauhut, 2003).
172. Humerus shaft torsion absent (0), or present (1) (Holtz, 1998).
173. distal condyles rounded (0), or flattened (1) (Carrano et
al.,
174. Deltopectoral crest extends distally humeral length (0),
or 245% humeral length or is small, only a low triangular
eminence (2) et al., 1998; Rauhut, 2003). (UO)
175. Radius length 250% or (1) humerus length et
al., 1998; Holtz,1998).
176. Radius and ulna distal articular surfaces not enlarged or large
and subhemispherical (1).
177. Distalcarpals I and separate or fuse to each other, resulting
in single element proximally capping metacarpals I and (1)
(Gauthier, 1986).
178. Distal ends of metacarpals dorsally rounded, smooth or with
deep, well developed extensor pits (1) et al., 1993).
179. Manual digit I proportions normal, with functionalphalanges or
digit reduced to sub
-
conical, blocky metacarpal that lacks distal
articular condyles and phalanges (1).
180. MetacarpalI and contactat proximal bases only (0), or proximal
half or more of metacarpal I closely appressed to metacarpal (1)
(Gauthier, 1986).
181. Metacarpal I with symmetrical distal articular condyles (0), or
strongly asymmetrical distal articular condyles, medial condyle
more proximal than lateral condyle (1) (Rauhut, 2003).
182. Phalanx I length or (1) (Rauhut,
2003).
183. digit (0), or manual digit (1) is longest of the
(Gauthier, 1986).
184. Manual digit penultimate phalanx length or
length of phalanx (Rauhut, 2003).
185. Manual digit penultimate phalanx length or
length of each of the more proximal digit phalanges (Rauhut,
186. Metacarpal to metacarpal or much smaller than
metacarpal (1) or absent (2) (Gauthier, 1986). ( 0)
187. Manual digit with (0), or (1) phalanx (modified from
Gauthier, 1986; Rauhut, 2003).
188. Manual digit V
with
prominent metacarpal and phalanx (0), or
is at most a vestigial metacarpal that lacks phalanges or is
absent (2) (Gauthier, 1986). ( 0)
189. Pelvic bones remain separate (0), or co
-
ossifywith one another (1)
by adulthood (Rowe, 1989; Rowe and Gauthier, 1990).
190. Ilium anteroposterior length shorter or about as long or longer
(1) than femur (Holtz,1998).
191. Dorsalmargin of ilium dorsally convex an d obviously curved (0), or
relatively (1) (modified from Carrano et al., 2002).
192. Preacetabularprocess of ilium does not extend past pubic peduncle
(0), or extends anteriorly well past pubic peduncle (1) (Gauthier,
1986; Carrano, 2000).
193. Preacetabularprocess of ilium stout and thick or relatively thin
and blade
-
like (1).
194. Ventral rim of preacetabular process of ilium relatively horizontal
or with ventral expansion or 'hook' (1) (modified from
Gauthier, 1986; et al. 1994).
195. Supraacetabular crest of ilium a weakly developed ridge or raised
shelf or flares lateroventrally to form hood
-
like overhang that
hides anterodorsal half of acetabulum in lateral view (1).
196. Brevis fossa of ilium narrow or broad (1) posteriorly et
1994, 1996).
197. Ilium postacetabular length or acetabulum width (1)
1999; Carrano, 2000; Carrano et al., 2002).
198. Posterior margin of ilium posteriorly convex or squared off or
concave, notched, or indentated (1) in lateral view
199. Ilium with M. iliofemoraliis fossa that reaches posterior rim of bone
(0), or stops short of bone's posterior margin, resulting in distinct
rim on lateral surface of postacetabular process (1) (modified from
Rowe,1989).
200. Pubic peduncle of ilium size approximately equal to or much
greater than (1) ischial peduncle et al.,1994).
201. Anteroposterior length of pubic peduncle of ilium times (0), or
times (1) mediolateral width (Gauthier, 1986; Carrano, 2000;
Carrano et al., 2002).
202. Pubic peduncle of ilium projects ventrally about as far as (0), or
much further than (1) ischial peduncle (Gauthier, 1986; Holtz,
203. Pubic peduncle of ilium with single distal facet (0), or two facets
separated by
kii,
resulting in anterior and ventral
-
oriented pubic
contacts (1) (modified from e t al., 1998).
204. Ilium
-
pubis articulation abutting (0), or with deep peg
-
in
-
socket
(socket in pubis) connection (1) (Sampson et al., 2001).
205. Proximal pubic plate ventromedial to obturator foramen solid (0),
or
with
pubic fenestra or pubic fenestra and obturator foramen
intersect to form obturator notch (2) (Rowe, 1989; Rowe and
Gauthier, 1990). (0 )
206. Mediolateralwidth of pubic 225% or (1) over
-
all shaft length.
207. of pubic shaft straight or curves anteriorly or curves ven
-
trally, resulting in anterior bowing (convex anterior, concave pos
-
terior) of shaft in lateral view (1) (Rowe,1989).
208. Medial lamina of pubis that reaches distal tip of shaft (0), or stops
short of distal tip of pubic shaft, resulting in short median separa
-
tion between distal tips of pubes (1).
209. Distal tips of pubes with median contact or without median
contact (1) from Holtz, 1998; Rauhut, 2000).
210. Distal tip of pubis substantial anteroposterior enlargement
(0), or enlarged times (1) or times (2) anteroposterior width
of pubic shaft (modified from Rauhut, 2003). ( 0)
211. Distal expansion of pubis continuous with or expanded laterally
beyond margin of shaft (0), or medially inset from lateral edge of
pubic shaft (1).
212. Distal tip of pubis elongate rectangular or subequant (0), or
angular (1) in distal view (modified from Rauhut, 2003).
213. Ischium length or (1) the length of pubis (Gauthier,
1986).
214. Ischial antitrochanter small, indistinct or large and protrudes
anterolaterally into acetabulum, giving 'notched' profile to
ventral margin of acetabulum (1) (Rowe and Gauthier, 1990;
215. Proximal plate of ischium solid or with fully enclosed ischial fora
-
men or ischial foramen ventrally open, cutting off obturator
process from anterior process of ischium (1) (modified from
Rauhut, 2003).
216. Obturator process of ischium continuouswith ischial shaft or
distally separated from ischial shaft by notch (1) (Rauhut, 1995;
Carrano et al., 2002).
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Distal tip of not anteroposteriorly enlarged (0), or enlarged
times or times (2) minimum anteroposterior width of
ischial shaft (modified from Novas, 1993; Rauhut, 2003).
Femoral head oriented anteromedially (0), or strictly medially (1)
when distal condyles set perpendicular to axial column (Novas,
1991; Holtz,1994).
Femoral head directed slightly ventrally (0), or horizontally or
slightly dorsally (1) (Harris, 1998).
Femoral head relatively continuous
with
posterior surface of femur
(0), or set off by welldefined oblique ligament groove on posterior
surface, giving 'hooked' proximal profile to femoral head (1)
(Rauhut, 2003).
Femoral dimorphism not present (0), or present, expressed in
muscle scars, attachments, and processes ('robust' versus 'gracile'
(1) (Rowe and Gauthier, 1990).
Femoral anterior trochanter a low ridge or tuberosity (0), or a
conicalspikeor pyramidal prominence or a mediolaterally com
-
pressed flange
(
=
aliform process) projecting anteriorly from femur
(2) (modified from Gauthier, 1986; Carrano, 2000). (UO)
Femoral anterior trochanter does not reach proximally to mid
-
point
of femoral head (0), or reaches proximallyat least to mid
-
point of
femoral head (1) (modified from Gauthier, 1986).
Femoral trochanteric shelf large and pronounced (0), or expressed
as low mound or swelling to anterior trochanter (1) in
adults (modified from Carrano et al.,
Medialepicondyle of femur weak (0), or strongly developed ridge
or hypertophied and flange
-
like (2) (Forster, 1999).
Anterior surface of femoral distal end flat or convex (0), or with
broad,shallow,depression bordered medially by medial epicondyle
(1) in adults (Rauhut, 2003).
Tibiofibular crest of femur smoothly continuouswith lateral distal
condyle (0), or sharply demarcated from lateral distal condyle by
or concavity (1) (Rowe,1989).
Femoral popliteal fossa smooth (0), or traversed by infrapopliteal
ridge betweenmedial
(=
tibial) distalcondyle and tibiofibular crest
(1) in adults.
Anteroposterior length of cnemialcrest of tibia or width
across proximal (=femoral) condyles of tibia.
Lateral surface of cnemial crest of tibia flat or excavated by
longitudinalfossa,giving tibia laterally 'hooked' profile in proximal
view (1) (modified from Sampson et al., 1998).
Proximal condyles of tibia continuous (0), or separated by cleft
along posterior
rim
of tibia in proximal view (1) (Rauhut, 2003).
Anterior tip of cnemial crest of tibia not expanded (0), or
modistallyexpanded (1) (Forster, 1999).
Fibular crest of tibia absent (0), or low ridge
extendingdistallyfrom proximal tibia or distally placed,
like, separated from proximal tibia (2) (Gauthier, 1986;
et al.,1993; Rauhut, 2003).
Tibia and fibula spaced apart (0), or closely appressed (1) through
most of shafts' length (Gauthier, 1986; Holtz,1994).
Distal end of tibia anteriorly flat or weakly convex (0), or with
broad anterior fossa bearing oblique (proximolateral to
dial) proximal border (1) (modification of Rauhut, 2003).
Tibia distal profile subequant to subrectangular (0), or
gularwith small posterolateral extension or subtriangularwith
large posterolateral expansion (2) (modified from Gauthier, 1986;
et al., 1994; Rauhut, 2003). (1). ( 0)
Medial side of proximal end of fibula flat (0), or excavated by
longitudinal groove (1) (modified from Rowe, 1989; Rowe and
Gauthier, 1990; Rauhut, 2003).
Medial side of proximal end of fibula flat or with oblique
teroproximal to anterodistal) ridge that overlaps proximal part of
medial fibular groove (1) (Rowe,1989; Rowe and Gauthier, 1990;
Rauhut, 2003).
Fibular M. insertion weak or (0), or dis
-
tinct small tubercle or large anterolaterally projecting tubercule
or process (2) (Rauhut, 2000; et al., 2002). ( 0)
Anteroposterior width of fibula or 530% (1)
anteroposterior width of proximal end of fibula
Fibula does not overlap astragalus (0), or bears medial flange that
overlaps part of the ascending process of astragalus (1) (Rowe,
1989; Rowe and Gauthier, 1990).
Fibula separate from (0), or co
-
ossifieswith (1) ascending process of
astragalusof adults (Carrano et al., 2002).
243. Fibularfacet on proximal surfaceof astragalus large, intersects pos
-
terior rim of astragalus(0), or large, does not reach posterior rim of
astragalus or small subtriangular fossa on anterolateral corner
of proximal surface of astragalus(2). ( 0)
244. Ascending process of astragalusheight or height of main
body of astragalus (Carrano et al., 2002).
245. Ascending process of astragalus positioned near center of astraga
-
proximalsurface (0), or near anteroproximal margin of astraga
-
(1).
246. facet of astragalus shallow and mostly medial to base of
ascending process (0), or deep and extends posterior to base of
ascending process (1) (Novas, 1989, 1996; Carrano et al., 2002).
247. Ascending process of astragalus robust, pyramidal prominence (0),
or anteroposteriorly flattened (1) e t al., 1994).
248. Anterior surface of astragalus smooth, not grooved (0), or traversed
by horizontalgroove (1) (Gauthier, 1986).
249. Astragalus and calcaneum remain separate (0), or fuse to each
other (1) by adulthood (Rowe 1989).
250. Astragalus and tibia remain separate (0), or fuse to each other (1)
by adulthood (Rowe, 1989).
251. without tibial facet (0), or with small tibial facet on
posteromedial corner or with large tibial facet covering most of
posterior surface and reaches nearly to lateral edge of
(2) et al., 1996; Rauhut, 2003).
(0)
252. Distal tarsal remains separate (0), or fuses to (1) metatarsal
by adulthood (modified from Rowe, 1989; Rowe and Gauthier,
1990).
253. Distal tarsal round or sub
-
rectangular or with large notch in
posterlateral comer (1).
254. Metatarsal
I
contacts ankle joint (0), or does not contact ankle joint
(1) of Gauthier, 1986; Rauhut, 2003).
255. Metatarsal
I
length 250% (0), or (1) length of metatarsal
(Gauthier, 1986).
256. Metatarsal
I
positionedon medial surface (0), or o n
surface (1) of metatarsal (Holtz,1998).
257. Proximal ends of metatarsals and remain separate (0), or
co
-
ossify to each other (1) by adulthood (Rowe, 1989).
258. Mediolateral width of metatarsal shaft approximately
=
widths
of and
IV
(0),or widthof
IV
and both (1) (Carrano et al.,
2002).
259. Proximal end of metatarsal does not back ventral side of meta
-
tarsals and
IV
(0), or backs metatarsals and ventrally,
resulting in proximal profile (
"
antarctometatarsus
"
)
260. Proximal end of metatarsal not ventrally enlarged (0), or with
ventral boss protruding beyond plane of metatarsal shafts (1).
261. Metatarsal
V
with distal articular surface (0), o r lacks distal articu
-
lation (1) (Gauthier, 1986; Rauhut, 2000).
262. Metatarsal
V
shaft round and straight (0), or mediolaterally flat
-
tened and distal end angles dorsally (anteriorly)(1) (modified from
Gauthier, 1986; Rauhut, 2003).
263. Pedal with single lateral groove (0), or two lateral grooves
(1) (Sampson et al., 2001; Novas and Bandyopadhyay, 2001).
264. of pedal digit symmetrical (0), or asymmetrical (1) (Car
-
rano et al., 2002).
APPENDIX 2. The scorings of the 264 characters for the 4
and the 30 taxa used in phylogenetic analysis. We coded
and the basal
Spinostropheus
into a matrix based upon that of Tykoski (2005). character states;
?:
could not be observed or missing data. Multistate characters in paren
-
theses a single were treated as
13
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Plateosaurus
Dilophosaurus
Elaphrosaurus
000000000000
Eoraptor
bauri
"
Ckayentakatae
111110011100
Zupaysaum
Ilokelesia
Abelisaurus
Carnotaurus
Majungatholm
14
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... Berberosaurus liassicus is another Gondwanan ceratosaurian from the Early Jurassic of Douar in Tazouda, Morocco. It is represented by associated postcranial elements and is usually recovered as an early-diverging ceratosaurian (Allain et al., 2007;Brougham et al., 2020;Dal Sasso et al., 2018;de Souza et al., 2021), but also less frequently as a non-averostran neotheropod (Langer et al., 2014). Finally, Elaphrosaurus bambergi is a ceratosaurian known from most of a postcranial skeleton from the Upper Jurassic Tendaguru Formation of Tanzania. ...
... Finally, Elaphrosaurus bambergi is a ceratosaurian known from most of a postcranial skeleton from the Upper Jurassic Tendaguru Formation of Tanzania. This species is frequently recovered as a noasaurid (Langer et al., 2019;Rauhut & Carrano, 2016;Rauhut & Pol, 2021;Wang et al., 2017) or a non-abelisauroid ceratosaurian (Agnolin et al., 2022;Allain et al., 2007;Brougham et al., 2020;Dal Sasso et al., 2018;Langer et al., 2014). In addition to these occurrences, four isolated teeth from the Upper Jurassic Tacuaremb o Formation of Uruguay have been referred to Ceratosaurus and several specimens from the Tendaguru Formation have been identified as probable indeterminate ceratosaurids, small abelisauroids, and probable abelisaurids (Rauhut, 2011;Soto et al., 2020). ...
... NHMUK PV R 16433 also shares with spinosaurids (and other megalosauroids) the rounded and poorly developed morphology of the medial epicondyle, which differs from the ridge-shaped structure present in ceratosaurs and allosauroids (Allain et al. 2007, Benson 2010, Carrano et al. 2012, Evans et al. 2015, Malafaia et al. 2018, Sereno et al. 2022, Lacerda et al. 2023, 2024, Cerroni et al. 2024, Isasmendi et al. 2024. ...
Article
The Kem Kem Group is a lowermost lithostratigraphic unit from the Upper Cretaceous that extends along the border between Algeria and Morocco, in the northern region of Africa. This geological unit has yielded several tetrapod fossils, including a well-represented assemblage of theropod dinosaurs, after more than eight decades of research. Here, we report new occurrences of spinosaurid theropods from the spinosaurine clade in the Kem Kem Group by providing anatomical descriptions and taxonomic identifications of 11 new specimens derived from the Tafilalt region of Morocco. Among the findings, we describe a cervical vertebra of Sigilmassasaurus, in addition to several cranial, axial, and appendicular elements that can safely be attributed to Spinosaurinae. Moreover, based on a unique combination of characteristics, we also describe an isolated and partial ischium belonging to an indeterminate carcharodontosaurid. We also deliver a detailed redescription of one of the most complete snouts of a spinosaurine known to date. Therefore, the theropod dinosaurs of the Kem Kem Group show considerable diversity, but many questions, especially related to the diversity of spinosaurids and the general abundance of carnivorous dinosaurs in this region, remain unclear until new materials are discovered and complete descriptions are made.
... The lesser trochanter is distinct and wing-like. As in Berberosaurus, Elaphrosaurus and Masiakasaurus [12,27,30], there is a pronounced attachment bulge (trochanteric shelf ) for m. iliofemoralis externus on the lateral side of the shaft at the base of lesser trochanter. The fourth trochanter is reduced to a low ridge, which is typical for abelisauroids [12,27]. ...
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The noasaurid ceratosaur Kiyacursor longipes gen. et sp. nov. is described based on a fragmentary skeleton including cervical vertebra, pectoral girdle, humerus and hind limbs from the Lower Cretaceous (Aptian) Ilek Formation at Shestakovo 1 locality in Western Siberia, Russia. This is the first ceratosaur from the Early Cretaceous of Asia, extending the stratigraphic range of Ceratosauria by 40 Myr on that continent. Kiyacursor shares unique hind limb proportions with Elaphrosaurus and Limusaurus, suggesting improved cursorial ability. These taxa show an ostrich-like specialization of the pes, with a large third metatarsal and greatly reduced second metatarsal. By contrast, all other fast running non-avian theropod dinosaurs have an arctometatarsalian pes, with the third metatarsal strongly reduced proximally. The new taxon lived in the Early Cretaceous ecosystem containing a number of other Jurassic relics, such as stem salamanders, protosuchian and shartegosuchid crocodyliforms, tritylodontid synapsids and docodontan mammaliaforms.
... By contrast, the facet for reception of the ascending process of the astragalus of NMS G.1994.10.1 is anteroposteriorly thicker than in averostran neotheropods (e.g. Ceratosaurus nasicornis: USNM 4735; Berberosaurus liassicus: Allain et al. 2007; Piatnitzkysaurus floresi: MACN-Pv CH 895) (Fig. 3l). ...
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The broadest diversification of early predatory dinosaurs is represented by the ‘coelophysoid-grade’ neotheropods, but their Hettangian–Sinemurian (ca. 191–201 Ma) record is scarce worldwide. More information is needed to shed light on the evolution of this dinosaur group after the end-Triassic mass extinction (ca. 201 Ma). Here we revisit the anatomy and phylogeny of one of these earliest Jurassic neotheropod specimens, an isolated partial tibia from the lower Sinemurian of the Isle of Skye (Scotland) that was previously identified as probably closely related to Liliensternus liliensterni and coelophysids. However, we found that the Skye specimen is positioned in the branch leading to Averostra (Ceratosauria + Tetanurae), in a polytomy with Sarcosaurus woodi from the late Hettangian–lower Sinemurian of central England and a clade composed of Tachiraptor admirabilis and Averostra. The morphology of the Skye specimen is congruent with that of referred specimens of Sarcosaurus woodi , but because it probably represents a skeletally immature specimen, we assign it to cf. Sarcosaurus woodi . The Skye specimen increases the number of averostran-line neotheropod specimens recorded in the Lower Jurassic of Europe and current evidence indicates that these forms, and not coelophysoids, were relatively common in this part of the world at that time. Thematic collection: This article is part of the Palaeontology of Scotland collection available at: https://www.lyellcollection.org/topic/collections/palaeontology-of-scotland Supplementary material: https://doi.org/10.6084/m9.figshare.c.6863016
... The coelophysoids disappeared during the Toarcian (Figs. 2 and 3). However, new basal Ceratosauria are recorded in the Toarcian such as Dandakosaurus from India (Yadagiri, 1982) and Berberosaurus from Morocco (Allain et al., 2007). After the Jenkyns Event, during the late Toarcian, the first allosauroids (Asfaltovenator; Metriacanthosauridae) and the first megalosauroids (Condorraptor and Piatnitzkysaurus; Piatnitzkysauridae) are recorded in South America (Rauhut, 2005;Carrano et al., 2012;Rauhut & Pol, 2019) (Fig. 2). Figure 2. Distribution of genera of sauropodomorphs, ornithischians and theropods from Hettangian to Aalenian. ...
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The early Toarcian Jenkyns Event (~183 Ma) was characterized by a perturbation of the global carbon cycle, global warming, which at continental areas led to intensified chemical weathering, enhanced soils erosion, and intensified wildfires. Warming and acid rain affected diversity and composition of land plant assemblages, caused a loss of forests and thereby impacted on trophic webs. The Jenkyns Event, triggered by volcanic activity of the Karoo-Ferrar Large Igneous Province, changed terrestrial ecosystems, and also affected the dinosaurs. Fossil macroplant assemblages and palynological data reveal reductions in the diversity and richness of plant communities. A substantial loss of land plant biomass and a shift to forests dominated by Cheiropelidiaceae conifers occurred as a consequence of seasonally dry and warm conditions. Major changes occurred to hervivore dinosaurs, with extinction of diverse basal families of Sauropodomorpha (‘prosauropods’) as well as some basal sauropods. Ornithischian dinosaurs show patchy records; some heterodontosaurids disappeared and the scelidosaurids (Thyreophora) went extinct during the Jenkyns Event. The dominant carnivorous dinosaurs, the Coelophysoidea (Theropoda), died out during the Jenkyns Event. We interpret the Jenkyns Event as a terrestrial crisis for ecosystems, marked especially by floral changes and the extinction of some dinosaur clades, both hervivores and carnivores.
... The beginning of the Toarcian was a major break in the evolution of theropods. The families Coelophysidae and Dilophosauridae disappeared during the Toarcian, but new basal Ceratosauria are recorded in the Toarcian such as Berberosaurus from Morocco (Allain et al., 2007) and Dandakosaurus from India (Yadagiri, 1982) (Figs. 5 and 7). After the Jenkyns Event, during the late Toarcian the first species of Allosauroidea is recorded, Asfaltovenator vialidadi from Cañadón Asfalto Basin (Argentina; Rauhut and Pol, 2019) at around 8 m length (Figs. 5 and 8) as well as the first megalosauroids of Family Piatnitzkysauridae (Condorraptor and Piatnitzkysaurus; Rauhut, 2005;Carrano et al., 2012). ...
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The Early Jurassic Jenkyns Event (~183 Ma) was characterized in terrestrial environments by global warming, perturbation of the carbon cycle, enhanced weathering and wildfires. Heating and acid rain on land caused a loss of forests and affected diversity and composition of land plant assemblages and the rest of the trophic web. We suggest that the Jenkyns Event, triggered by the activity of the Karoo-Ferrar Large Igneous Province, was pivotal in remodelling terrestrial ecosystems, including plants and dinosaurs. Macroplant assemblages and palynological data show reductions in diversity and richness of conifers, cycadophytes, ginkgophytes, bennetitaleans, and ferns, and continuation of seasonally dry and warm conditions. Major changes occurred to sauropodomorph dinosaurs, with extinction of diverse basal families formerly called ‘prosauropods’ as well as some basal sauropods, and diversification of the derived Eusauropoda in the Toarcian in South America, Africa, and Asia, and wider diversification of new families, including Mamenchisauridae, Cetiosauridae and Neosauropoda (Dicraeosauridae and Macronaria) in the Middle Jurassic, showing massive increase in size and diversification of feeding modes. Ornithischian dinosaurs show patchy records; some heterodontosaurids and scelidosaurids disappeared, and major new clades (Stegosauridae, Ankylosauridae, Nodosauridae) emerged soon after the Jenkyns Event, in the Bajocian and Bathonian worldwide. Among theropod dinosaurs, Coelophysidae and Dilophosauridae died out during the Jenkyns Event and a diversification of theropods (Megalosauroidea, Allosauroidea, Tyrannosauroidea) occurred after this event with substantial increases in size. We suggest then that the Jenkyns Event terrestrial crisis was marked especially by floral changes and origins of major new sauropodomorph and theropod clades, characterized by increasing body size. Comparison with the end Triassic Mass Extinction helps to understand the incidence of climatic changes driven by activity of large igneous provinces on land ecosystems and their great impacts on early dinosaur evolution.
... Ceratosaurs (abelisaurids) have been described, for example from Aalenian-Bajocian deposits of Argentina (Pol and Rauhut 2012). From the Toundoute continental series (Lower Jurassic, Pliensbachian-Toarcian) of the Quarzazate area, High Atlas, Morocco, the medium-sized abelisauroid Berberosaurus liassicus was described (Allain et al. 2007). The early allosauroid Asfaltovenator vialidadi was documented from the famous Cañadon-Asfalto beds (Toarcian-Bajocian) of Argentina (Rauhut and Pol 2019). ...
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Tridactyl theropod and ornithischian dinosaur tracks and trackways from Imilchil and Isli formations (Middle–?Late Jurassic, Bajocian–?) of the central High Atlas region (Morocco) are described. The Imilchil Formationconsists of brackish marine-continental deposits, and the Isli Formation is a continental red-bed succession. Considering numerous new footprint discoveries, including recently described Polyonyx sauropod trackways, tridactyl dinosaur tracks from the Imilchil-Tounfite region are revised. Dominating are theropod footprints resembling the ichnogenus Changpeipus and known from Lower-Middle Jurassic deposits of China. Other theropod ichnotaxa are Trisauropodiscus isp., cf. Wildeichnus isp.,Carmelopodus isp., Megalosauripus isp., Kayentapus isp. and an indeterminate small grallatorid. Ornithischians are represented by small indeterminate ornithischian tracks, large ornithischian footprints cf. Stegopodus isp. and a large indeterminate ornithopod form. Makers of the small theropod trackswere small coelurosaurs or basal tetanurans, larger forms belong toceratosaurs, megalosauroids, allosauroids or tyrannosauroids. Ornithischian tracks suggest dryomorphs, iguanodontians and thyreophorans as producers. Together with crocodylomorph and pterosaur tracks, invertebrate traces and plants, the Imilchil and Isli formations document a flourishing ecosystem and dinosaur habitat. Remarkable is the presence of Changpeipus theropod tracks known from abundant occurrences in East Asia. This suggests an exchange of dinosaur faunas between this region and northern Africa during the Middle Jurassic.
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Gondwanan dinosaur faunae during the 20 Myr preceding the Cretaceous-Palaeogene (K/Pg) extinction included several line-ages that were absent or poorly represented in Laurasian landmasses. Among these, the South American fossil record contains diverse abelisaurids, arguably the most successful groups of carnivorous dinosaurs from Gondwana in the Cretaceous, reaching their highest diversity towards the end of this period. Here we describe Koleken inakayali gen. et sp. n., a new abelisaurid from the La Colonia Formation (Maastrichtian, Upper Cretaceous) of Patagonia. Koleken inakayali is known from several skull bones, an almost complete dorsal series, complete sacrum, several caudal vertebrae, pelvic girdle and almost complete hind limbs. The new abelisaurid shows a unique set of features in the skull and several anatomical differences from Carnotaurus sas-trei (the only other abelisaurid known from the La Colonia Formation). Koleken inakayali is retrieved as a brachyrostran abeli-saurid, clustered with other South American abelisaurids from the latest Cretaceous (Campanian-Maastrichtian), such as Aucasaurus, Niebla and Carnotaurus. Leveraging our phylogeny estimates, we explore rates of morphological evolution across ceratosaurian lineages, finding them to be particularly high for elaphrosaurine noasaurids and around the base of Abelisauridae, before the Early Cretaceous radiation of the latter clade. The Noasauridae and their sister clade show contrasting patterns of morphological evolution, with noasaurids undergoing an early phase of accelerated evolution of the axial and hind limb skeleton in the Jurassic, and the abelisaurids exhibiting sustained high rates of cranial evolution during the Early Cretaceous. These results provide much needed context for the evolutionary dynamics of ceratosaurian theropods, contributing to broader understanding of macroevolutionary patterns across dinosaurs.
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Theropod dinosaurs likely radiated in the wake of the End-Triassic Extinction, but the early history of their diversification remains obscure. The Elliot Formation (EF) and its lateral equivalents in southern Africa preserves abundant continental Late Triassic and Early Jurassic vertebrate fossils, representing an opportunity to study the early phases of theropod evolution. However, Elliot Formation theropod remains are scarce relative to other dinosaurian groups, and most of the South African record pertains to a single taxon, Megapnosaurus rhodesiensis. We present morphological and osteohistological data on two theropod distal tibiae from South Africa’s upper EF. The two new tibiae are larger than any known specimens of M. rhodesiensis, and they show a fast-growing woven-parallel complex (WPC). One of the specimens bears a line of arrested growth, but neither shows outer circumferential lamellae. These observations suggest that both specimens are immature and distinguishable from M. rhodesiensis based on osteohistology. Comparative anatomical observations, including body mass comparisons, further support this distinction. We cannot rule out an identification for one of our tibiae as Dracovenator regenti, the only other valid EF theropod taxon known from body fossils. Our observations indicate that there is likely at least one additional, relatively large-bodied upper EF theropod species that remains unknown from adequate skeletal material.
Article
Skorpiovenator bustingorryi is a derived abelisaurid theropod represented by a fairly complete skeleton from the Late Cretaceous sedimentary beds of north-western Patagonia. Although some features were described in the original paper, mainly related to the skull, the appendicular anatomy remains undescribed. The aim of the present contribution is to provide a detailed description and analysis of the available appendicular bones, including comparisons with other ceratosaurian theropods close to Skorpiovenator. In this way, new autapomorphies emerged to further distinguish Skorpiovenator from its relatives. Furthermore, a comprehensive phylogenetic analysis was performed and several characteristics of the hind limb, in particular some of the autopodium, resulted in the identification of new apomorphic traits for Ceratosauria and Abelisauridae. These features might prove to be useful for future phylogenetic analyses and may help to resolve the still confusing and debated internal relationships of abelisaurid theropods.
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I report here on the discovery of the most complete megalosaurid skull known to date, from the Calcaire de Caen Formation of northwesten France. The specimen, which represents a new species is questionably referred to Poekilopleuron. It includes a nearly complete, unornamented skull, characterized by its low lateral profile. In addition to its historical significance, it provides additional characters that are crucial for reconstructing the phylogeny and biogeography of basal theropods. Poekilopleuron? valesdunensis new species is closely related to Eustreptospondylus and Afrovenator, and is united with Torvosaurus in the family of Megalosauridae. The Megalosauridae appear less derived than the Allosauroidea but resemble the Spinosauridae, with which they form the sister-group to the Neotetanurae. The proposed phylogenetic analysis hypothesizes two previously unrecognized major radiations of carnivorous dinosaurs.
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Until now, Syntarsus was based on a single species, S. rhodesiensis, known only from southern Africa. The discovery of Syntarsus in North America adds significantly to the increasingly detailed resemblance of African and North American Early Jurassic terrestrial vertebrate faunas. The new species, Syntarsus kayentakatae, is based on a complete skull and partial skeleton, and more fragmentary remains of at least 16 additional individuals, all from a narrow stratigraphie interval in the Kayenta Formation. Syntarsus kayentakatae is diagnosed by parasagittal cranial crests and fusion of the fibula to the calcaneum in adults. Syntarsus is the most derived member of the newly diagnosed theropod taxon Ceratosauria, possessing 22 apomorphies that arose subsequent to the divergence of ceratosaurs from other theropods. Syntarsus shares 20 of these with Coelophysis bauri, one of the earliest well-known theropods. By their first appearance, probably late Carnian, ceratosaurs already possessed a history involving considerable morphological transformation. A number of these characters arose convergently much later in time in ornithurine birds.
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Continental strata of Early Jurassic age are seldom exposed, and little is known of the history of sauropod dinosaurs prior to the Middle Jurassic radiation of neosauropods. Well-preserved skeletons and skulls have not been recovered from strata older than the Middle Jurassic. Here we report, in the Early Jurassic of the Moroccan High Atlas, the discovery of the skeleton, including cranial material, of a new vulcanodontid sauropod. Tazoudasaurus naimi n.g., n.sp. represents with Vulcanodon the sister group of the eusauropods and the most complete basal sauropod material available to date. To cite this article: R. Allain