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Introduction
Abelisauridae a family of big Gondwanic preda-
tors very abundant during the Late Cretaceous. Both
in diversity and in numbers of specimens,
abelisaurids are the best documented theropod di-
nosaurs in South America (Novas, 1997). However,
most of these fossils are known only from isolated
fragmentary bones or partial skeletons. Until now,
Carnotaurus sastrei (Bonaparte, 1985; Bonaparte et al.,
1990) and Aucasaurus garridoi (Coria et al., 2002) are
the most complete specimens of the family Abelisau-
ridae. We describe a new Abelisauridae theropod,
Ekrixinatosaurus novasi gen. et sp. nov. based on a
partial skeleton found disarticulated and dispersed
over 15 m2. The present anatomical description fo-
cuses on the most novel information preserved in
Ekrixinatosaurus novasi, including portions of the
skeleton that are unknown, unpublished, or poorly
preserved in other abelisaurs. The discovery oc-
curred due to excavations for building a gas pipeline
(Gasoducto del Pacífico Company) in Bajo del Añelo
(figure 1), Neuquén Province, Argentina.
The known distribution of Abelisauridae mem-
bers in South America, Madagascar and India have
allowed to evaluate the hypothesis of a dispersion
route between South America and the Indo -
Madagascar plate through Antarctica by a terrestrial
bridge (Kerguelen Plateau) during the late
Cretaceous (Sampson et al., 1998). This hypothesis is
based on a divergence of the clade, posterior to the
separation of Africa and South America. However,
the recent report of an Abelisauridae maxilar in
Cenonian-Turonian beds has changed the diver-
gence of this clade toward the same continental
break (Lamanna et al. 2002). According to these au-
thors, this finding may show a pan-Gondwanic dis-
tribution of this family.
Abbreviation. MUCPv, Museo Universidad
Nacional del Comahue, Paleovertebrados, Neu-
quén.
1Centro Paleontológico Lago Barreales, Universidad Nacional del
Comahue, Ruta Provincial 51, kilómetro 65. Neuquén, Argentina.
2Universidad de Chile, Laboratorio de Zoología de Vertebrados,
Facultad de Ciencias. Las Palmeras 3425, Santiago, Chile.
3Museo Nacional de Historia Natural, Sección Paleontología.
Casilla 787, Santiago, Chile.
4Universidad Austral de Chile, Instituto de Geociencias. Casilla
567, Valdivia, Chile.
A new Abelisauridae (Dinosauria: Theropoda)
from northwest Patagonia
Jorge O. CALVO1, David RUBILAR-ROGERS2,3 and Karen MORENO4
Key words. Dinosauria. Abelisauridae. Systematic. Phylogeny. Patagonia.
Palabras clave. Dinosauria. Abelisauridae, Sistemática. Filogenia. Patagonia.
Abstract. A new theropod Abelisauridae is described, Ekrixinatosaurus novasi gen. et sp. nov., of north-
western Patagonia (Neuquén Province, Argentina). A preliminar cladistic analysis placed Ekrixinatosaurus
together with Majungatholus and Carnotaurini; and the sister group is Ilokelesia. The presence of this spec-
imen in Albian-Cenomanian beds allows us to support the early divergence (pre-Senonian) of this clade,
and the hypothesis of the presence of Abelisauridae in continental Africa. The present distribution of
Abelisauridae indicates: 1) a vicariance of this clade based on a pre-Cenomanian pan-Gondwanic distrib-
ution; 2) dispersion throughout terrestrial bridges. In both cases, the absence of Abelisauridae in conti-
nental Africa can be considered a bias of the fossil record.
Resumen. UN NUEVO ABELISAURIDAE (DINOSAURIA: THEROPODA) DEL NOROESTE DE LA PATAGONIA. Se describe
un nuevo terópodo Abelisauridae, Ekrixinatosaurus novasi gen. et sp. nov., del noroeste de la Patagonia
(provincia del Neuquén, Argentina). Un análisis cladístico preliminar ubica a Ekrixinatosaurus en un nodo
junto a Majungatholus y Carnotaurini; y a Ilokelesia como grupo hermano. La presencia de este espécimen
en capas del Albiano-Cenomaniano permite sustentar la divergencia temprana (pre-Senoniana) de este
clado y la hipótesis de la presencia en Africa continental de Abelisauridae. La presente distribución de
Abelisauridae puede reflejar: 1) una vicarianza de este clado a partir de una distribución pan-Gondwánica
pre-Cenomaniana; 2) dispersión a través de puentes terrestres. En ambos casos, la ausencia de Abelisau-
ridae en África continental puede considerarse un sesgo del registro fósil.
AMEGHINIANA (Rev. Asoc. Paleontol. Argent.) - 41 (4): 555-563. Buenos Aires, 30-12-2004 ISSN 0002-7014
©Asociación Paleontológica Argentina AMGHB2-0002-7014/04$00.00+.50
J.O. Calvo, D. Rubilar-Rogers and K. Moreno
556
Systematic paleontology
THEROPODA Marsh, 1881
NEOCERATOSAURIA Novas, 1992
ABELISAURIA Novas, 1992
ABELISAURIDAE Bonaparte and Novas 1985
Ekrixinatosaurus gen. nov.
Type species. Ekrixinatosaurus novasi sp. nov.
Etymology. From the Greek Ekrixi, meaning “explo-
sion”; the Latin nato, meaning “born”, referred to the
fact that the fossil was discovered after its rocky
tomb was dynamited; and the Greek saurus, meaning
“reptile” or “lizard”.
Diagnosis. As for the species.
Ekrixinatosaurus novasi sp. nov.
(Figures 2, 3, 4, 5, 6, 7, 8)
Holotype. MUCPv-294, a well preserved disarticu-
lated skeleton with elements including: left and par-
tial right maxillae; basicranium; both dentaries; teeth;
cervical, a dorsal, sacral and caudal vertebrae;
haemal arches; ribs; ilia, pubis and proximal ischia;
left and distal end of right femur; left tibia; left astra-
galus and calcaneum; proximal end of left fibula and
right tibia; metatarsals; phalanges; and a pedal un-
gual.
Etymology. novasi, in honor of Dr. Fernando Novas
for his important contributions to the study of
abelisaurid theropods.
Diagnosis. Ekrixinatosaurus novasi is a large abelisaur
theropod, between 7 to 8 m of total length, distin-
guished by the following characters: presence of a
fenestra between the postorbital and the anterior bor-
der of the frontal; protuberance directed backward on
the contact between the parietals with the paraoccipi-
tal process. Cervical vertebrae cranio-caudally com-
pressed; cervical neural spines as tall as the epipophy-
ses; mid-posterior cervical centrum with ventral side
flattened; two wide foramina in the mid-posterior cer-
vicals; small preespinal depression with a pneumatic
excavation connected to the neural canal in the mid-
dle-posterior cervicals; small pre-spinal lamina in
mid-cervicals; tibia with a swelling at midshaft.
Locality. Approximately 34 km northwest of Añelo,
Neuquén Province, northwestern Patagonia,
Argentina (figure 1).
AMEGHINIANA 41 (4), 2004
Figure 1. Map of Neuquén Province (northwest Patagonia) show-
ing where Ekrixinatosaurus novasi was found / Mapa de la provincia
del Neuquén (noroeste de la Patagonia) mostrando la localidad de hallaz-
go de Ekrixinatosaurus novasi.
Figure 2. Skeletal reconstruction of Ekrixinatosaurus novasi gen. et sp. nov. Scale bar 1 m / Reconstrucción del esqueleto de Ekrixinatosaurus
novasi gen. et sp. nov. Escala 1 m.
A new theropod dinosaur from Patagonia 557
Horizon. The material comes from red beds belong-
ing to the Candeleros Formation, Río Limay Group,
Albian-Cenomanian (“Middle” Cretaceous) (Calvo,
1999). The Candeleros Formation has surrendered an
assemblage of vertebrate remains: the theropod
Giganotosaurus (Coria and Salgado, 1995), the sau-
ropods Rebbachisaurus and Andesaurus as well as
some titanosaurid remains, the crocodile Araripe-
suchus, a pipid frog, fragments of turtles, pterosaur
tracks and a wide variety of dinosaur trackways
(Calvo, 1991, 1999).
Description
Skull
The supraoccipital has a prominent posterior pro-
jection. The occipital crest is a relatively thin bone
composed of the parietals and part of the squamosal.
In posterior view the crest is convex and the parietal
is horizontal. The paraoccipital process is not com-
plete distally; however, it is subtriangular and direct-
ed ventroposteriorly. The occipital condyle and ba-
sioccipitals are missing. The parietals are fused to the
frontals. There is a protuberance directed backward
on the contact between the parietals with the paraoc-
cipital process. The frontal is a wedge-shaped block
with a flat dorsal surface. The median suture is fused
and is a straight line. The anterior portion of the
frontal is missing. The contact between frontal and
postorbital is fused. Both participate on the anterior
border of the supratemporal fenestra. The postorbital
is incomplete, just its dorsal portion is preserved and
part of the ventral process. The postorbital has a ro-
bust anterior projection that produces a fenestra be-
tween the postorbital and the anterior border of the
frontal. The squamosal is small and triradiate. The
anterior ramus is covered by the posterior projection
of the postorbital. It is not possible to see if the
squamosal participates in the supratemporal fenes-
tra. The ventral projection has a subtriangular sec-
tion. The posteroventral projection is small. The
parasphenoid is a medial ossification that is widely
fused to the ventral faces of the frontals. Ventrally
this ossification is laminar.
The maxilla is short (42 cm long) and high, with
one dorsoventrally elongated maxillary fenestra lo-
cated near the anterior border of the preorbital open-
ing (figure 3). There are 16 alveoli, some with teeth.
They are flattened laterally with anterior and posteri-
or serrations.
Mandible. The dentary is short with a convex ventral
border (figure 4). It is low and elongated anteropos-
teriorly. In lateral view it is curved with its distal end
rounded. In medial view, the Meckelian groove is
shallow anteriorly, becoming deeper and wider pos-
teriorly. It extends near the lower border of the den-
tary. The posterior third of the dentary is vertically
expanded. The interdental plates occupy half of the
lingual surface from the first alveoli to the seventh,
then becomes smaller posteriorly.
Postcranial skeleton
Vertebral column
Presacral vertebrae. Few presacral vertebrae are pre-
served in the holotype specimen MUCPv-294. There
is a small, poorly preserved anterior cervical. The
neural arch is partially preserved, just a small distal
portion of the diapophysis and is directed backward.
The centrum is opisthocoelous and longer than wide.
In lateral view, the anterior face of the centrum
makes a sharp angle with the anteroposterior plane,
indicating the limits of the dorsoventral flexion of
the neck. There are two small pleurocoels on the lat-
eral side of the centrum (figure 5). The parapophysis
is well developed. In ventral view there is a promi-
nent hypapophysis that extends from the middle of
the centra to the anterior border. In posterior view a
large cavity that leads into the neural arch is exposed.
There is a complete mid-posterior cervical verte-
brae (figure 5). The neural spine is low and broad,
barely surpassing the level of the epipophysis. The
neural arch has a small preespinal lamina, and small
prespinal depressions. The epipophysis are well de-
veloped, posterolaterally oriented and with no cra-
nial projections. In lateral view the diapophyseal
lamina is reduced. The parapophysis are well devel-
oped. In anterior view the neural arch has two big
pneumatic cavities above the neural channel. There is
AMEGHINIANA 41 (4), 2004
Figure 3. Ekrixinatosaurus novasi, left maxilla showing the ascen-
dant subvertical ramus. Scale bar 10 cm / Maxilar izquierdo
mostrando la rama ascendente subvertical. Escala 10 cm.
J.O. Calvo, D. Rubilar-Rogers and K. Moreno
558
a centroprezygapophyseal lamina that surrounds an-
teriorly a lateral depression. The postzygapophyses
are large and directed obliquely and ventrally. In
posterior view the wide depression behind the neur-
al spine has two rather large fenestrae that lead into
the neural arch.
A dorsal centrum is known and it is am-
phiplatyan. In anterior view, the articular face is cir-
cular and it is bigger than the posterior one. In later-
al view there is a depression with a small pleurocoel
placed anteriorly. The lateral side is convex
dorsoventrally and concave anteroposteriorly.
Caudal vertebrae. Anterior caudal vertebra are large
and robusts. The centra are amphicoelous. The later-
al surface of the centra shows a slight depression.
The ventral face of the transverse processes has a
strong ridge that extends from the anterior portion of
the centra to the distal end of the transverse process.
In lateral view, the distal end of the transverse
process extends beyond the posterior face of the cen-
tra. The thin laminar neural spine is directed back-
ward. Middle and posterior caudals are also amph-
icoelous and their centra are longer than high. The
transverse processes are directed backward and
slightly upward. Middle caudals present fore and aft
process on the distal end of the transverse processes
(figure 6). Posteriorly, the caudals have horizontal
transverse processes. The neural spine, placed poste-
riorly, is high, laterally compressed and directed
backward. Both postzygapophyses and prezy-
gapophyses are well developed.
Hindlimb
The left femur is complete (figure 7). The diaphy-
sis is almost straight in posterior view, but in lateral
view is slightly sigmoidal. The head is directed an-
teromedially at 45º with respect to the femur axis.
The head is hemispherical, with the articular surface
smooth. The anterior trochanter, partially preserved,
projects anteriorly. The fourth trochanter is robust
and prominent; its crest is directed posteromedially.
At the distal end the condyles project posteriorly.
The internal tibial condyle is larger and it is com-
pressed laterally as are the external tibial and the
fibular. The external tibial condyle is small. In medi-
al view, at the distal end, there is a strong ridge that
clearly separates the medial and anterior faces.
Tibia, astragalus and calcaneum. These three bones are
fused. The left tibia (69 cm) is shorter and more slen-
der than the femur. In anterior view the diaphysis is
straight. The distal end is twisted 90º with respect to
the proximal one. The cnemial crest is well devel-
oped, its internal border is convex and the external
one is concave. The articulation for the femur has a
lateral articular condyle bordered in posterior view
by a sulcus. Distally the tibia is wider in order to ac-
commodate the fused astragalus and calcaneum (fig-
ure 8). A suture is seen between the tibia and astra-
galus-calcaneum in anterior view, but none between
astragalus and calcaneum. The ascending process of
the astragalus is small (6 cm).
AMEGHINIANA 41 (4), 2004
Figure 4. Ekrixinatosaurus novasi, left dentary with the convex ven-
tral border. Scale bar 10 cm / dentario izquierdo con el borde ventral
convexo. Escala 10 cm.
Figure 5. Ekrixinatosaurus novasi, mid-posterior cervical vertebra
(in anterior view) showing the hypertrophied epipophyses and
the height of the neural spine / cervical media-posterior (en vista an-
terior) mostrando la epitrofisis hipertrofiada y la altura de la espina neu-
ral.
A new theropod dinosaur from Patagonia 559
Discussion and comparisons
The skull is estimated to be ~ 83 cm long based on
comparison with Carnotaurus and Majungatholus
(Bonaparte et al., 1990; Sampson et al., 1998).
Unfortunately, Abelisaurus does not have a complete
maxilla but its preserved size is similar to
Ekrixinatosaurus. On the other hand, the femoral
length of Ekrixinatosaurus is 77 cm (figure 7), where-
as that of Carnotaurus was estimated to be 103 cm.
The Ekrixinatosaurus skull / femur length ratio is es-
timated to be 1.08 whereas in Carnotaurus it is be-
lieved to have been about 0.58 and Ceratosaurus =
1.00. Ekrixinatosaurus possesses a robust maxilla,
with a subvertical ascending process and fused inter-
dental plates, as in other members of Abelisauria.
Based on the shape of the ascending process of the
maxilla the preorbital opening is higher than long,
similar to that present in Carnotaurus. The dentary is
short with a convex ventral border as in other
Abelisauridae and Ceratosaurus (figure 4). In the bas-
icranium the supraoocipital has a prominent posteri-
or projection as in Carnotaurus. The protuberance di-
rected backward from the contact between the pari-
etals with the paraoccipital process is an autapomor-
phy of Ekrixinatosaurus. The postorbital has an ante-
rior robust projection that produces a fenestra be-
tween the postorbital and the anterior border of the
frontal, this condition is not present in other mem-
bers of the Abelisauridae (character present here as
autapomorphy). A lateral projection of the postor-
bital is present as in Abelisaurus.
Ekrixinatosaurus has hypertrophied epipophyses
and deep postspinal depressions as in Abelisauria
(Novas, 1992). Unlike Carnotaurus, the posterior face
of each anterior cervical centrum is strongly concave
while the anterior surface is almost flat. In the mid-
posterior cervicals the neural arch is relatively high
with anteroposteriorly compressed neural spine,
which is different than Ilokelesia (Coria and Salgado,
1998). Like in Carnotaurus, Noasaurus, Ilokelesia and
Aucasaurus there is a lamina that connects the
epipophysis with the prezygapophysis that separates
the dorsal surface of the neural arch from the lateral
surface. Ilokelesia has an autapomorphy, cervical ver-
tebrae with poorly defined diapopostzygapofiseal
laminae. This character is also present in Ekrixi-
natosaurus. It is probably a synapomorphy for Abe-
lisauridae.
The anterior dorsal vertebrae are amphiplatyan. It
shares with Carnotaurus the presence of pleurocoels
in dorsals; this character is not present in Ilokelesia.
All preserved sacrals are fused to the sacral ribs
and to the ilium as in adult Ceratosauria.
On caudal vertebrae the posterolaterally project-
ing transverse processes are inclined slightly dorsal-
ly, which is different than Ilokelesia where they are
perpendicular to the dorsoventral axis of the verte-
bra, and to Carnotaurus where they are strongly in-
clined upward. Anterior caudals show wide trans-
verse processes that are cranially expanded at the
AMEGHINIANA 41 (4), 2004
Figure 7. Ekrixinatosaurus novasi, left femur in lateral view. Scale
bar 10 cm / fémur izquierdo en vista lateral. Escala 10 cm.
Figure 6. Ekrixinatosaurus novasi, mid-caudal in dorsal view show-
ing the antero-posteriorly expanded distal end of the transverse
processes. Scale bar 10 cm / vértebra media-caudal en vista dorsal
mostrando la expansión distal del proceso transverso. Escala 10 cm.
J.O. Calvo, D. Rubilar-Rogers and K. Moreno
560
distal end as in Carnotaurus (figure 6). In Ekrixi-
natosaurus the transverse processes are directed
slightly upward and backward. The ventral side of
each transverse process has a strong ridge along all
its length. Ekrixinatosaurus is the first abelisaurid
with posterior caudals that are known. These are am-
phicoelous and have laterally flattened subtriangular
neural spines. As in Carnotaurus the distal end of the
transverse process is expanded having a process di-
rected anteriorly. Ekrixinatosaurus shares with
Ilokelesia the fore and aft process on the distal end of
the transverse processes in middle caudals: this char-
acter was defined as autapomorphic for Ilokelesia.
However, we consider this character as a synapo-
morphy of the Abelisauridae. The distal edge of the
caudal transverse processes is slightly concave in the
middle in Ilokelesia and Ekrixinatosaurus. It has been
considered an autapomorphy of Ilokelesia, but we in-
terpret it as a synapomorphy of Abelisauridae.
The length of the ilium is close to that of the femur
as in other members of the Neoceratosauria.As in all
Ceratosauria the tibia, astragalous and calcaneous
are fused.
Phylogenetic relationships
The phylogenetic relationships between Ekrixi-
natosaurus and the most complete members of
Abelisauridae were evaluated in a preliminary
cladistic analysis using some diagnostic characters
(see appendix). Ekrixinatosaurus is more closely relat-
ed to Carnotaurini (Coria et al., 2002) than to
Neoceratosauria. Thirteen binary characters were
used. The matrix was analyzed using PAUP 4.0*b10
(Swofford, 2000) under heuristic search, and charac-
ter-state transformations were evaluated under AC-
CTRAN optimization. This analysis produced two
most parsimonious trees with a Tree Length of 14,
Consistency Index of 0.9286 and Retention Index of
0.9375 (figure 9.A). Strict consensus tree generates a
politomy among Majungatholus, Ekrixinatosaurus and
Carnotaurini; however, Ilokelesia is placed as the sister
group (figure 9.B).
Phylogenetic studies place abelisaurids within a
big subdivision of Theropoda, the Ceratosauria
(Gauthier, 1986; Rowe and Gauthier, 1990; Novas,
1991; Holtz, 1994). At least two principal groups are
recognized within Ceratosauria: Coelophysoidea,
(Upper Triassic and Lower Jurassic) which includes
Coelophysis (Cope, 1889), Syntarsus (Raath, 1969) and
Dilophosaurus (Welles, 1984) from North America,
Europe and Africa; and Neoceratosauria (Upper Ju-
rassic) which includes Ceratosaurus (Gilmore, 1920)
from North America and Elaphrosaurus (Janensch,
1920, 1929) from Africa. In the Cretaceous the last
Neoceratosauria is represented by abelisaurids living
in Gondwanan sub-continents (South America, Ma-
dagascar and India).
Originally, Ceratosauria included Coelophysidae
(Dilophosaurus, Coelophysis and Syntarsus) and Cerato-
saurus (Rowe and Gauthier, 1990). Later, several au-
thors recognized valid synapomorphies between
Abelisauridae and Ceratosaurus, and the clade Neo-
ceratosauria (Novas, 1992) was erected to include
Ceratosaurus, Abelisauridae and Noasaurus. Subse-
quently Elaphrosaurus and Ligabueino have been in-
cluded in a clade named Abelisauroidea (Bonaparte,
1991a, 1996; Holtz, 1994). However, the inclusion of
Elaphrosaurus has been questioned (Holtz, 1994;
Padian et al., 1999), as well as the monophyly of this
group (Rowe et al., 1997; Padian et al., 1999). Finally,
some differences between Noasaurus and Abelisau-
ridae (Bonaparte and Powell, 1980; Bonaparte and
Novas, 1985) were recognized, and the name Abeli-
sauria was erected by Novas (1992).
The family Abelisauridae (Bonaparte and Novas,
1985; Novas, 1997; Sampson et al., 1998) is character-
ized by: middle and anterior cervicals with anterior
process on each epipophysis; anteroposteriorly short
and deep premaxilla; dorsoventrally deep snout at
the level of the narial openings; frontals dorsoven-
trally thickened; posterior surface of the basioccipital
wide and smooth below the occipital condyle; loose
contacts among dentary, splenial and all theropod
postdentary bones; premaxilla with reduced to ab-
sent palatal process; rostral process of the lacrimal
strongly reduced or absent; lacrimal with pronunced
suborbital process; broad lacrimal-postorbital con-
AMEGHINIANA 41 (4), 2004
Figure 8. Ekrixinatosaurus novasi, co-ossified astragalus and calca-
neum; note the short ascending process on the astragalus / astrá-
galo coosificado y calcáneo; nótese el proceso ascendente corto en el as-
trágalo.
A new theropod dinosaur from Patagonia 561
tact; long axis of postorbital oriented rostroventral-
caudodorsal; postorbital with a pronounced subor-
bital process. We add: neural spine in posterior cer-
vicals lower than epipophyses, and large transverse
processes with fore and aft extensions on the distal
end of the middle and posterior caudals, recognized
by Coria et al. (2002) as an autopomorphy of
Aucasaurus garridoi.
Fossil record and distribution of abelisaurids
The fossil record of abelisaurids includes
Ligabueino andesi (Bonaparte, 1996) from the Lower
Cretaceous of South America, Xenotarsosaurus bona-
partei (Martínez et al., 1986), Ilokelesia aguadagranden-
sis (Coria and Salgado, 1998) and Ekrixinatosaurus no-
vasi from the “Middle” Cretaceous of South America;
Noasaurus leali (Bonaparte and Powell, 1980),
Abelisaurus comahuensis (Bonaparte and Novas, 1985),
Carnotaurus sastrei (Bonaparte, 1985; Bonaparte et al.,
1990), Velocisaurus unicus (Bonaparte, 1991b),
Aucasaurus garridoi (Coria et al., 2002), Indosuchus rap-
torius (Huene and Matley, 1933), Indosaurus matleyi
(Huene and Matley, 1933), Majungatholus atopus and
Masiakasaurus knopfleri (Sampson et al., 1998; 2001)
from the Upper Cretaceous of South America, India
and Madagascar.
The fossil record of abelisaurids in continental
Africa (Russell, 1996) has been controversial (Samp-
son et al., 1998). Sampson et al. (1998) proposed that
the origins of Abelisauridae occurred after the isola-
tion of Africa; therefore, the present distribution of
this clade is the result of dispersion between the
AMEGHINIANA 41 (4), 2004
Figure 9. A, one of the two most parsimonious trees obtained in this study showing the phylogenetic relationships of Ekrixinatosaurus
novasi gen. et sp. nov. The tree is based on 13 characters. TL = 14; CI = 0.9286; RI = 0.9375; RC = 0.8705. B, Strict consensus tree / A, uno
de los dos árboles más parsimoniosos que se obtuvieron en este estudio mostrando las relaciones filogenéticas de Ekrixinatosaurus novasi gen. et sp.
nov. El árbol está basado en 13 caracteres. TL = 14; CI = 0.9286; RI = 0.9375; RC = 0.8705. B, Árbol de consenso estricto.
J.O. Calvo, D. Rubilar-Rogers and K. Moreno
562
Indo-Madagascan province and South America
through continental links that persisted until the Late
Cretaceous. According to this hypothesis, abeli-
saurids never existed in continental Africa. On the
other hand, Lamanna et al. (2002) report an Abeli-
sauridae maxilla from the early Late Cretaceous
(middle Cenomanian-Turonian) deposits, extended
the origin of this family to pre-Senonian (Coniacian-
Maastrichtian) times. These authors suggest that the
known occurrence of Abelisauridae may reflect a for-
mer pan-Gondwanan distribution. The discovery of
Ekrixinatosaurus in the Candeleros Formation (Al-
bian-Cenomanian) is consistent with this hypothesis.
Nevertheless, an additional scenario is that Abeli-
sauridae entered continental Africa via a landbridge,
between NE Brazil and Nigeria-Cameroon, before
the major continental fragmentation of the Cenoma-
nian-Turonian. This hypothesis is based on the
strong faunal similarity of the Albian-Cenomanian
fossil assemblage found in Patagonia represented by
carcharodontosaurid theropods (Coria and Salgado,
1995; Sereno et al., 1996), Diplodocimorpha,
Titanosauria, and Titanosauridae sauropods; and
those recorded in northwestern continental Africa
(Calvo, 1999).
Acknowledgments
We thank to Leonardo Salgado and Susana Heredia (Museo de
Paleontología, Universidad Nacional del Comahue) for their help
and useful comments. We also thank to J. Hutchinson (University
of California, Berkeley), P. Currie (Tyrrell Museum of
Palaeontology), K. Carpenter (Denver Museum of Natural
History) and G. Paul for reviewing and improving the manuscript
and the English version. J. Bonaparte and F. Novas (Museo
Argentino de Ciencias Naturales “Bernardino Rivadavia”) for let-
ting us see the holotype of Carnotaurus and for providing us infor-
mation about abelisaurids; and R. Coria (Museo Municipal de
Plaza Huincul) for access to specimens under his care. The
Sociedad Paleontológica de Chile (SPACH) also helped in differ-
ent aspects of this study. This work was supported by Gaseoducto
del Pacífico Company, the National University of Comahue and
ANCyT-BID 802/OC-AR-PICT N07-01513/99 to JOC.
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Recibido: 25 de marzo de 2004.
Aceptado: 10 de noviembre de 2004.
Appendix
List of 13 character and character status of Neotheropoda used for
cladistic analysis (table 1). character codes: 0, primitive; 1, derived;
? missing or uncertain. Some sources for the character analysis are:
Coria et al. 2002; Coria and Salgado, 1998; Gauthier, 1986; Novas,
1991; 1992; Sampson et al., 1998; Carrano et al., 2002.
Cranium
1) Maxilla-jugal contact posteroventral directed: 0, absent; 1, pre-
sent.
2) Subvertical ascendent ramus of the maxilla: 0, absent; 1, pre-
sent.
3) Ventral convex border of dentary: 0, absent; 1, present.
4) Skull, external sculpturing: 0, absent; 1, present.
5) Frontals and parietals: 0, unfused, 1, fused.
6) maxilla-jugal contact: 0, short; 1, long, broad.
7) ventral process of postorbital: 0, ventrally; 1, o cranioventrally
projected.
8) Intraorbital projection of ventral process of postorbital: 0, ab-
sent; 1, present.
Postcranium
9) Cranial process of cervical epipophyses: 0, absent; 1, present.
10) Hypertrophied epipophysis: 0, absent; 1, present.
11) High of neural spine in cervicals: 0, considerably higher than
epipophysis; 1, lower or equal than epipophysis.
12) Dorsal surface of cervical neural arches clearly delimited
from lateral surface of diapophyses: 0, absent; 1, present.
13) Transverse processes of caudal vertebrae: 0, unexpanded or 1,
expanded anteroposteriorly at ends
Table 1. Data matrix for the distribution of the 13 characters listed
above among the 8 taxa considered / Matriz de platos para la dis-
tribución de 13 caracteres para los 8 taxones considerados.
Taxon 5 10
TETANURAE 0 0 0 0 0 0 0 0 0 0 0 0 0
Ceratosaurus 1 0 100 000 00000
Ilokelesia ? ? ??? ?01 01111
Carnotaurus 1 1 111 111 11111
Ekrixinatosaurus 1 1 111 ?11 01111
Majungatholus 1 1 111 111 0111 ?
Masiakasaurus ? ? 00? ??? 01100
Aucasaurus 1 11111??11111
AMEGHINIANA 41 (4), 2004
