The carcharodontosaurid theropod Mapusaurus
roseae (Cenomanian of Neuque´n Province, Argentina) ... more The carcharodontosaurid theropod Mapusaurus
roseae (Cenomanian of Neuque´n Province, Argentina) is
represented by at least seven disarticulated individuals
from a monospecific bonebed, all of different sizes and
presumably different stages of maturity. We report a series
of anatomical differences between repeated skull bones of
Mapusaurus, which we interpret as produced by peramorphic
heterochronic processes. The materials analyzed
include maxillae, lacrimals, dentaries, and isolated teeth.
Most of the differences were recorded in the maxilla, the
most noticeable change being the reduction of the pneumaticity.
We found that some of the synapomorphic
characters of derived carcharodontosaurids appear to be the
result of peramorphic heterochronies, as in the strongly
ornamented facial bones, and the single opening in the
anteroventral corner of the antorbital fossa in the maxilla.
The theropod clade Carcharodontosauridae is a broadly distributed group of large allosauroid ther... more The theropod clade Carcharodontosauridae is a broadly distributed group of large allosauroid theropods. The
carcharodontosaurids recorded in the Albian – Cenomanian of Gondwana are the youngest and most derived members of this
clade. Tyrannotitan chubutensis, from the Cerro Castan˜ o Member of Cerro Barcino Formation (Albian; Chubut Group),
Central Patagonia, Argentina, is of prime interest among Gondwanan carcharodontosaurids as it represents the oldest record
of the group. Here we offer a detailed osteological comparative description of the holotype and paratype of Tyrannotitan
chubutensis together with a new diagnosis of the species. The new information results in a better understanding of this taxon
and Carcharodontosauridae. Furthermore, a comparative study of the anatomy of the pectoral girdle of Giganotosaurus is
reinterpreted as very similar to that of Tyrannotitan and Mapusaurus. We also present a phylogenetic analysis of
Carcharodontosauridae that recovers Tyrannotitan as a derived carcharodontosaurid, being the sister group of the clade
formed by Giganotosaurus and Mapusaurus, all nested in the clade Giganotosaurini
A nearly complete skeleton of the new abelisaurid
Skorpiovenator bustingorryi is reported here. T... more A nearly complete skeleton of the new abelisaurid Skorpiovenator bustingorryi is reported here. The holotype was found in Late Cenomanian–Early Turonian outcrops of NW Patagonia, Argentina. This new taxon is deeply nested within a new clade of South American abelisaurids, named Brachyrostra. Within brachyrostrans, the skull shortening and hyperossification of the skull roof appear to be correlated with a progressive enclosure of the orbit, a set of features possibly related to shock-absorbing capabilities. Moreover, the development of horn-like structures and differential cranial thickening appear to be convergently acquired within Abelisauridae. Based on the similarities between Skorpiovenator and carcharodontosaurid tooth morphology, we suggest that isolated teeth originally referred as post-Cenomanian Carcharodontosauridae most probably belong to abelisaurids.
Patagonia has yielded the most comprehensive fossil record of Cretaceous theropods from Gondwana,... more Patagonia has yielded the most comprehensive fossil record of Cretaceous theropods from Gondwana, consisting of 31 nominal species belonging to singleton taxa and six families: Abelisauridae, Noasauridae, Carcharodontosauridae, Megaraptoridae nov. fam., Alvarezsauridae, and Unenlagiidae. They provide anatomical information that allows improved interpretation of theropods discovered in other regions of Gondwana. Abelisauroids are the best represented theropods in Patagonia. They underwent an evolutionary radiation documented fromthe Early Cretaceous through to the latest Cretaceous, and are represented by the clades Abelisauridae and Noasauridae. Patagonian carcharodontosaurids are known from three taxa (Tyrannotitan, Giganotosaurus and Mapusaurus), as well as from isolated teeth, collected from Aptian to Cenomanian beds. These allosauroids constituted the top predators during the mid-Cretaceous, during which gigantic titanosaur sauropodswere the largest herbivores. Megaraptorans have become better documented in recent years with the discovery of more complete remains. Megaraptor, Aerosteon and Orkoraptor have been described from Cretaceous beds from Argentina, and these taxa exhibit close relationships with the Aptian genera Australovenator, from Australia, and Fukuiraptor, from Japan. The Gondwanan megaraptorans are gathered into the newfamily Megaraptoridae, and the Asiatic Fukuiraptor is recovered as the immediate sister taxon of this clade. Although megaraptorans have been recently interpreted as members of Allosauroidea, we present evidence that they are deeply nested within Coelurosauria. Moreover, anatomical information supports Megaraptora as more closely related to the Asiamerican Tyrannosauridae than thought. Megaraptorans improve our knowledge about the scarcely documented basal radiation of Gondwanan coelurosaurs and tyrannosauroids as awhole. Information at hand indicates that SouthAmericawas a cradle for the evolutionary radiation for different coelurosaurian lineages, including some basal forms (e.g., Bicentenaria, Aniksosaurus), megaraptorans, alvarezsaurids less derived than those of Laurasia, and unenlagiids, revealing that Gondwanan coelurosaurs played sharply differing ecological roles, and that theywere taxonomically as diverse as in the northern continents. The unenlagiids represent an endemic South American clade that has been recently found to be more closely related to birds than to dromaeosaurid theropods. Analysis of the theropod fossil record from Gondwana shows the highest peak of origination index occurred during the AptianeAlbian and a less intense one in the Campanian time spans. Additionally, peaks of extinction index are recognized for the Cenomanian and TuronianeConiacian time spans. In comparison, the Laurasianpattern differs fromthat of Gondwana in the presence of an older extinction event during the AptianeAlbian time-span and a high origination rate during the Cenomanian time-bin. Both Laurasian and Gondwanan theropod records show a peak of origination rates during the Campanian.
The proximal portion of the left ulna of a pterosaur is described. The specimen comes from
the Ca... more The proximal portion of the left ulna of a pterosaur is described. The specimen comes from the Candeleros Formation (Cenomanian), Neuquén Group, at Cabo Alarcón, Neuquén province, Argentina. The analysis of this new specimen allows the re-‐‑interpretation of a previously described pterosaur tibia founded at Los Catutos locality, Neuquén (MOZ 2280 P) as a proximal ulna. The new material belongs to a medium-‐‑sized pterosaur, considerably larger than previously recorded pterosaurs from this geological unit. The analysis of correlation between ulnar length-‐‑pes length in well-‐‑known pterodactyloid pterosaurs shows that the new ulna matches well with the inferred size of the Pteraichnus isp. trackmaker recorded from the same formation.
Diplodocids are by far the most emblematic sauropod dinosaurs. They are part of Diplodocoidea, a ... more Diplodocids are by far the most emblematic sauropod dinosaurs. They are part of Diplodocoidea, a vast clade whose other
members are well-known from Jurassic and Cretaceous strata in Africa, Europe, North and South America. However,
Diplodocids were never certainly recognized from the Cretaceous or in any other southern land mass besides Africa. Here
we report a new sauropod, Leikupal laticauda gen. et sp. nov., from the early Lower Cretaceous (Bajada Colorada Formation)
of Neuque´n Province, Patagonia, Argentina. This taxon differs from any other sauropod by the presence of anterior caudal
transverse process extremely developed with lateroventral expansions reinforced by robust dorsal and ventral bars, very
robust centroprezygapophyseal lamina in anterior caudal vertebra and paired pneumatic fossae on the postzygapophyses
in anterior-most caudal vertebra. The phylogenetic analyses support its position not only within Diplodocidae but also as a
member of Diplodocinae, clustering together with the African form Tornieria, pushing the origin of Diplodocoidea to the
Middle Jurassic or even earlier. The new discovery represents the first record of a diplodocid for South America and the
stratigraphically youngest record of this clade anywhere.
Sauropod haemal arches are caudal bony structures that have been traditionally incorporated into ... more Sauropod haemal arches are caudal bony structures that have been traditionally incorporated into two different types observed in different anatomical views: Y-shaped (anterior view) and forked (lateral view). This research proposes a classification combining information observed in anterior and lateral views. Four types of ‘Y-shaped’ and six types of ‘V-shaped’ chevrons were recognised. Complete chevron series in some eusauropods allows the comparison of topological equivalent structures along the tail and also among taxa. A basal titanosaur from Argentina exhibits mid-caudal chevron morphology in which more than one cranial and caudal process is present, arising from the distal blades as well as from the proximal rami, a condition not seen before in a sauropod dinosaur. The morphological variability seen in sauropod chevrons along the tail is in close relationship with the development and distribution of muscle. caudofemoralis longus, as seen in extant crocodiles and as previously proposed for non-avian theropods and for caudal centra and transverse processes of sauropod dinosaurs. Two new characters related to middle chevrons are proposed here, in which the transitional morphology is described.
A complete endocast of Giganotosaurus carolinii CORIA & SALGADO, 1995 was made in
latex after rem... more A complete endocast of Giganotosaurus carolinii CORIA & SALGADO, 1995 was made in latex after removing mechanically the sediment filling of the cerebral cavity of the braincase, thereby allowing the description of the endocranial anatomy of the specimen. The endocast was compared with the other few known natural or artificial theropod endocasts, including the two species of the African allosauroid species Carcharodontosaurus saharicus and C. idiguensis. As in Carcharodontosaurus, the olfactory bulbs in Giganotosaurus are aligned with the forebrain, the midbrain is posteroventrally inclined and the hindbrain is parallel but ventral to the forebrain, showing similarly angled cephalic and pontine flexures. The cranial nerves and blood vessels have a similar disposition as in Carcharodontosaurus saharicus. However, in Giganotosaurus there is only one branch for cranial nerve XII, and cranial nerve XI has a separate internal opening from the vagus foramen (metotic foramen). In C. saharicus, there is a separate opening as well, but it is anterior in position and was probably utilized by cranial nerve IX. The length of the endocast of Giganotosaurus, including the olfactory bulbs, is approximately 19 % longer than the endocast in Carcharodontosaurus saharicus.
The carcharodontosaurid theropod Mapusaurus
roseae (Cenomanian of Neuque´n Province, Argentina) ... more The carcharodontosaurid theropod Mapusaurus
roseae (Cenomanian of Neuque´n Province, Argentina) is
represented by at least seven disarticulated individuals
from a monospecific bonebed, all of different sizes and
presumably different stages of maturity. We report a series
of anatomical differences between repeated skull bones of
Mapusaurus, which we interpret as produced by peramorphic
heterochronic processes. The materials analyzed
include maxillae, lacrimals, dentaries, and isolated teeth.
Most of the differences were recorded in the maxilla, the
most noticeable change being the reduction of the pneumaticity.
We found that some of the synapomorphic
characters of derived carcharodontosaurids appear to be the
result of peramorphic heterochronies, as in the strongly
ornamented facial bones, and the single opening in the
anteroventral corner of the antorbital fossa in the maxilla.
The theropod clade Carcharodontosauridae is a broadly distributed group of large allosauroid ther... more The theropod clade Carcharodontosauridae is a broadly distributed group of large allosauroid theropods. The
carcharodontosaurids recorded in the Albian – Cenomanian of Gondwana are the youngest and most derived members of this
clade. Tyrannotitan chubutensis, from the Cerro Castan˜ o Member of Cerro Barcino Formation (Albian; Chubut Group),
Central Patagonia, Argentina, is of prime interest among Gondwanan carcharodontosaurids as it represents the oldest record
of the group. Here we offer a detailed osteological comparative description of the holotype and paratype of Tyrannotitan
chubutensis together with a new diagnosis of the species. The new information results in a better understanding of this taxon
and Carcharodontosauridae. Furthermore, a comparative study of the anatomy of the pectoral girdle of Giganotosaurus is
reinterpreted as very similar to that of Tyrannotitan and Mapusaurus. We also present a phylogenetic analysis of
Carcharodontosauridae that recovers Tyrannotitan as a derived carcharodontosaurid, being the sister group of the clade
formed by Giganotosaurus and Mapusaurus, all nested in the clade Giganotosaurini
A nearly complete skeleton of the new abelisaurid
Skorpiovenator bustingorryi is reported here. T... more A nearly complete skeleton of the new abelisaurid Skorpiovenator bustingorryi is reported here. The holotype was found in Late Cenomanian–Early Turonian outcrops of NW Patagonia, Argentina. This new taxon is deeply nested within a new clade of South American abelisaurids, named Brachyrostra. Within brachyrostrans, the skull shortening and hyperossification of the skull roof appear to be correlated with a progressive enclosure of the orbit, a set of features possibly related to shock-absorbing capabilities. Moreover, the development of horn-like structures and differential cranial thickening appear to be convergently acquired within Abelisauridae. Based on the similarities between Skorpiovenator and carcharodontosaurid tooth morphology, we suggest that isolated teeth originally referred as post-Cenomanian Carcharodontosauridae most probably belong to abelisaurids.
Patagonia has yielded the most comprehensive fossil record of Cretaceous theropods from Gondwana,... more Patagonia has yielded the most comprehensive fossil record of Cretaceous theropods from Gondwana, consisting of 31 nominal species belonging to singleton taxa and six families: Abelisauridae, Noasauridae, Carcharodontosauridae, Megaraptoridae nov. fam., Alvarezsauridae, and Unenlagiidae. They provide anatomical information that allows improved interpretation of theropods discovered in other regions of Gondwana. Abelisauroids are the best represented theropods in Patagonia. They underwent an evolutionary radiation documented fromthe Early Cretaceous through to the latest Cretaceous, and are represented by the clades Abelisauridae and Noasauridae. Patagonian carcharodontosaurids are known from three taxa (Tyrannotitan, Giganotosaurus and Mapusaurus), as well as from isolated teeth, collected from Aptian to Cenomanian beds. These allosauroids constituted the top predators during the mid-Cretaceous, during which gigantic titanosaur sauropodswere the largest herbivores. Megaraptorans have become better documented in recent years with the discovery of more complete remains. Megaraptor, Aerosteon and Orkoraptor have been described from Cretaceous beds from Argentina, and these taxa exhibit close relationships with the Aptian genera Australovenator, from Australia, and Fukuiraptor, from Japan. The Gondwanan megaraptorans are gathered into the newfamily Megaraptoridae, and the Asiatic Fukuiraptor is recovered as the immediate sister taxon of this clade. Although megaraptorans have been recently interpreted as members of Allosauroidea, we present evidence that they are deeply nested within Coelurosauria. Moreover, anatomical information supports Megaraptora as more closely related to the Asiamerican Tyrannosauridae than thought. Megaraptorans improve our knowledge about the scarcely documented basal radiation of Gondwanan coelurosaurs and tyrannosauroids as awhole. Information at hand indicates that SouthAmericawas a cradle for the evolutionary radiation for different coelurosaurian lineages, including some basal forms (e.g., Bicentenaria, Aniksosaurus), megaraptorans, alvarezsaurids less derived than those of Laurasia, and unenlagiids, revealing that Gondwanan coelurosaurs played sharply differing ecological roles, and that theywere taxonomically as diverse as in the northern continents. The unenlagiids represent an endemic South American clade that has been recently found to be more closely related to birds than to dromaeosaurid theropods. Analysis of the theropod fossil record from Gondwana shows the highest peak of origination index occurred during the AptianeAlbian and a less intense one in the Campanian time spans. Additionally, peaks of extinction index are recognized for the Cenomanian and TuronianeConiacian time spans. In comparison, the Laurasianpattern differs fromthat of Gondwana in the presence of an older extinction event during the AptianeAlbian time-span and a high origination rate during the Cenomanian time-bin. Both Laurasian and Gondwanan theropod records show a peak of origination rates during the Campanian.
The proximal portion of the left ulna of a pterosaur is described. The specimen comes from
the Ca... more The proximal portion of the left ulna of a pterosaur is described. The specimen comes from the Candeleros Formation (Cenomanian), Neuquén Group, at Cabo Alarcón, Neuquén province, Argentina. The analysis of this new specimen allows the re-‐‑interpretation of a previously described pterosaur tibia founded at Los Catutos locality, Neuquén (MOZ 2280 P) as a proximal ulna. The new material belongs to a medium-‐‑sized pterosaur, considerably larger than previously recorded pterosaurs from this geological unit. The analysis of correlation between ulnar length-‐‑pes length in well-‐‑known pterodactyloid pterosaurs shows that the new ulna matches well with the inferred size of the Pteraichnus isp. trackmaker recorded from the same formation.
Diplodocids are by far the most emblematic sauropod dinosaurs. They are part of Diplodocoidea, a ... more Diplodocids are by far the most emblematic sauropod dinosaurs. They are part of Diplodocoidea, a vast clade whose other
members are well-known from Jurassic and Cretaceous strata in Africa, Europe, North and South America. However,
Diplodocids were never certainly recognized from the Cretaceous or in any other southern land mass besides Africa. Here
we report a new sauropod, Leikupal laticauda gen. et sp. nov., from the early Lower Cretaceous (Bajada Colorada Formation)
of Neuque´n Province, Patagonia, Argentina. This taxon differs from any other sauropod by the presence of anterior caudal
transverse process extremely developed with lateroventral expansions reinforced by robust dorsal and ventral bars, very
robust centroprezygapophyseal lamina in anterior caudal vertebra and paired pneumatic fossae on the postzygapophyses
in anterior-most caudal vertebra. The phylogenetic analyses support its position not only within Diplodocidae but also as a
member of Diplodocinae, clustering together with the African form Tornieria, pushing the origin of Diplodocoidea to the
Middle Jurassic or even earlier. The new discovery represents the first record of a diplodocid for South America and the
stratigraphically youngest record of this clade anywhere.
Sauropod haemal arches are caudal bony structures that have been traditionally incorporated into ... more Sauropod haemal arches are caudal bony structures that have been traditionally incorporated into two different types observed in different anatomical views: Y-shaped (anterior view) and forked (lateral view). This research proposes a classification combining information observed in anterior and lateral views. Four types of ‘Y-shaped’ and six types of ‘V-shaped’ chevrons were recognised. Complete chevron series in some eusauropods allows the comparison of topological equivalent structures along the tail and also among taxa. A basal titanosaur from Argentina exhibits mid-caudal chevron morphology in which more than one cranial and caudal process is present, arising from the distal blades as well as from the proximal rami, a condition not seen before in a sauropod dinosaur. The morphological variability seen in sauropod chevrons along the tail is in close relationship with the development and distribution of muscle. caudofemoralis longus, as seen in extant crocodiles and as previously proposed for non-avian theropods and for caudal centra and transverse processes of sauropod dinosaurs. Two new characters related to middle chevrons are proposed here, in which the transitional morphology is described.
A complete endocast of Giganotosaurus carolinii CORIA & SALGADO, 1995 was made in
latex after rem... more A complete endocast of Giganotosaurus carolinii CORIA & SALGADO, 1995 was made in latex after removing mechanically the sediment filling of the cerebral cavity of the braincase, thereby allowing the description of the endocranial anatomy of the specimen. The endocast was compared with the other few known natural or artificial theropod endocasts, including the two species of the African allosauroid species Carcharodontosaurus saharicus and C. idiguensis. As in Carcharodontosaurus, the olfactory bulbs in Giganotosaurus are aligned with the forebrain, the midbrain is posteroventrally inclined and the hindbrain is parallel but ventral to the forebrain, showing similarly angled cephalic and pontine flexures. The cranial nerves and blood vessels have a similar disposition as in Carcharodontosaurus saharicus. However, in Giganotosaurus there is only one branch for cranial nerve XII, and cranial nerve XI has a separate internal opening from the vagus foramen (metotic foramen). In C. saharicus, there is a separate opening as well, but it is anterior in position and was probably utilized by cranial nerve IX. The length of the endocast of Giganotosaurus, including the olfactory bulbs, is approximately 19 % longer than the endocast in Carcharodontosaurus saharicus.
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Papers by Juan Ignacio Canale
roseae (Cenomanian of Neuque´n Province, Argentina) is
represented by at least seven disarticulated individuals
from a monospecific bonebed, all of different sizes and
presumably different stages of maturity. We report a series
of anatomical differences between repeated skull bones of
Mapusaurus, which we interpret as produced by peramorphic
heterochronic processes. The materials analyzed
include maxillae, lacrimals, dentaries, and isolated teeth.
Most of the differences were recorded in the maxilla, the
most noticeable change being the reduction of the pneumaticity.
We found that some of the synapomorphic
characters of derived carcharodontosaurids appear to be the
result of peramorphic heterochronies, as in the strongly
ornamented facial bones, and the single opening in the
anteroventral corner of the antorbital fossa in the maxilla.
carcharodontosaurids recorded in the Albian – Cenomanian of Gondwana are the youngest and most derived members of this
clade. Tyrannotitan chubutensis, from the Cerro Castan˜ o Member of Cerro Barcino Formation (Albian; Chubut Group),
Central Patagonia, Argentina, is of prime interest among Gondwanan carcharodontosaurids as it represents the oldest record
of the group. Here we offer a detailed osteological comparative description of the holotype and paratype of Tyrannotitan
chubutensis together with a new diagnosis of the species. The new information results in a better understanding of this taxon
and Carcharodontosauridae. Furthermore, a comparative study of the anatomy of the pectoral girdle of Giganotosaurus is
reinterpreted as very similar to that of Tyrannotitan and Mapusaurus. We also present a phylogenetic analysis of
Carcharodontosauridae that recovers Tyrannotitan as a derived carcharodontosaurid, being the sister group of the clade
formed by Giganotosaurus and Mapusaurus, all nested in the clade Giganotosaurini
Skorpiovenator bustingorryi is reported here. The
holotype was found in Late Cenomanian–Early Turonian
outcrops of NW Patagonia, Argentina. This new taxon is
deeply nested within a new clade of South American
abelisaurids, named Brachyrostra. Within brachyrostrans,
the skull shortening and hyperossification of the skull roof
appear to be correlated with a progressive enclosure of the
orbit, a set of features possibly related to shock-absorbing
capabilities. Moreover, the development of horn-like structures
and differential cranial thickening appear to be
convergently acquired within Abelisauridae. Based on the
similarities between Skorpiovenator and carcharodontosaurid
tooth morphology, we suggest that isolated teeth originally
referred as post-Cenomanian Carcharodontosauridae most
probably belong to abelisaurids.
consisting of 31 nominal species belonging to singleton taxa and six families: Abelisauridae, Noasauridae,
Carcharodontosauridae, Megaraptoridae nov. fam., Alvarezsauridae, and Unenlagiidae. They provide
anatomical information that allows improved interpretation of theropods discovered in other regions of
Gondwana. Abelisauroids are the best represented theropods in Patagonia. They underwent an evolutionary
radiation documented fromthe Early Cretaceous through to the latest Cretaceous, and are represented by the
clades Abelisauridae and Noasauridae. Patagonian carcharodontosaurids are known from three taxa (Tyrannotitan,
Giganotosaurus and Mapusaurus), as well as from isolated teeth, collected from Aptian to Cenomanian
beds. These allosauroids constituted the top predators during the mid-Cretaceous, during which
gigantic titanosaur sauropodswere the largest herbivores. Megaraptorans have become better documented
in recent years with the discovery of more complete remains. Megaraptor, Aerosteon and Orkoraptor have
been described from Cretaceous beds from Argentina, and these taxa exhibit close relationships with the
Aptian genera Australovenator, from Australia, and Fukuiraptor, from Japan. The Gondwanan megaraptorans
are gathered into the newfamily Megaraptoridae, and the Asiatic Fukuiraptor is recovered as the immediate
sister taxon of this clade. Although megaraptorans have been recently interpreted as members of Allosauroidea,
we present evidence that they are deeply nested within Coelurosauria. Moreover, anatomical
information supports Megaraptora as more closely related to the Asiamerican Tyrannosauridae than
thought. Megaraptorans improve our knowledge about the scarcely documented basal radiation of Gondwanan
coelurosaurs and tyrannosauroids as awhole. Information at hand indicates that SouthAmericawas a
cradle for the evolutionary radiation for different coelurosaurian lineages, including some basal forms (e.g.,
Bicentenaria, Aniksosaurus), megaraptorans, alvarezsaurids less derived than those of Laurasia, and unenlagiids,
revealing that Gondwanan coelurosaurs played sharply differing ecological roles, and that theywere
taxonomically as diverse as in the northern continents. The unenlagiids represent an endemic South
American clade that has been recently found to be more closely related to birds than to dromaeosaurid
theropods. Analysis of the theropod fossil record from Gondwana shows the highest peak of origination
index occurred during the AptianeAlbian and a less intense one in the Campanian time spans. Additionally,
peaks of extinction index are recognized for the Cenomanian and TuronianeConiacian time spans. In
comparison, the Laurasianpattern differs fromthat of Gondwana in the presence of an older extinction event
during the AptianeAlbian time-span and a high origination rate during the Cenomanian time-bin. Both
Laurasian and Gondwanan theropod records show a peak of origination rates during the Campanian.
the Candeleros Formation (Cenomanian), Neuquén Group, at Cabo Alarcón, Neuquén province,
Argentina. The analysis of this new specimen allows the re-‐‑interpretation of a previously described
pterosaur tibia founded at Los Catutos locality, Neuquén (MOZ 2280 P) as a proximal ulna. The
new material belongs to a medium-‐‑sized pterosaur, considerably larger than previously recorded
pterosaurs from this geological unit. The analysis of correlation between ulnar length-‐‑pes length in
well-‐‑known pterodactyloid pterosaurs shows that the new ulna matches well with the inferred size
of the Pteraichnus isp. trackmaker recorded from the same formation.
members are well-known from Jurassic and Cretaceous strata in Africa, Europe, North and South America. However,
Diplodocids were never certainly recognized from the Cretaceous or in any other southern land mass besides Africa. Here
we report a new sauropod, Leikupal laticauda gen. et sp. nov., from the early Lower Cretaceous (Bajada Colorada Formation)
of Neuque´n Province, Patagonia, Argentina. This taxon differs from any other sauropod by the presence of anterior caudal
transverse process extremely developed with lateroventral expansions reinforced by robust dorsal and ventral bars, very
robust centroprezygapophyseal lamina in anterior caudal vertebra and paired pneumatic fossae on the postzygapophyses
in anterior-most caudal vertebra. The phylogenetic analyses support its position not only within Diplodocidae but also as a
member of Diplodocinae, clustering together with the African form Tornieria, pushing the origin of Diplodocoidea to the
Middle Jurassic or even earlier. The new discovery represents the first record of a diplodocid for South America and the
stratigraphically youngest record of this clade anywhere.
observed in different anatomical views: Y-shaped (anterior view) and forked (lateral view). This research proposes
a classification combining information observed in anterior and lateral views. Four types of ‘Y-shaped’ and six types of
‘V-shaped’ chevrons were recognised. Complete chevron series in some eusauropods allows the comparison of topological
equivalent structures along the tail and also among taxa. A basal titanosaur from Argentina exhibits mid-caudal chevron
morphology in which more than one cranial and caudal process is present, arising from the distal blades as well as from the
proximal rami, a condition not seen before in a sauropod dinosaur. The morphological variability seen in sauropod chevrons
along the tail is in close relationship with the development and distribution of muscle. caudofemoralis longus, as seen in
extant crocodiles and as previously proposed for non-avian theropods and for caudal centra and transverse processes of
sauropod dinosaurs. Two new characters related to middle chevrons are proposed here, in which the transitional morphology
is described.
latex after removing mechanically the sediment filling of the cerebral cavity of the braincase, thereby
allowing the description of the endocranial anatomy of the specimen. The endocast was compared
with the other few known natural or artificial theropod endocasts, including the two species of the
African allosauroid species Carcharodontosaurus saharicus and C. idiguensis. As in Carcharodontosaurus,
the olfactory bulbs in Giganotosaurus are aligned with the forebrain, the midbrain is posteroventrally
inclined and the hindbrain is parallel but ventral to the forebrain, showing similarly angled
cephalic and pontine flexures. The cranial nerves and blood vessels have a similar disposition as in
Carcharodontosaurus saharicus. However, in Giganotosaurus there is only one branch for cranial
nerve XII, and cranial nerve XI has a separate internal opening from the vagus foramen (metotic
foramen). In C. saharicus, there is a separate opening as well, but it is anterior in position and
was probably utilized by cranial nerve IX. The length of the endocast of Giganotosaurus, including
the olfactory bulbs, is approximately 19 % longer than the endocast in Carcharodontosaurus
saharicus.
roseae (Cenomanian of Neuque´n Province, Argentina) is
represented by at least seven disarticulated individuals
from a monospecific bonebed, all of different sizes and
presumably different stages of maturity. We report a series
of anatomical differences between repeated skull bones of
Mapusaurus, which we interpret as produced by peramorphic
heterochronic processes. The materials analyzed
include maxillae, lacrimals, dentaries, and isolated teeth.
Most of the differences were recorded in the maxilla, the
most noticeable change being the reduction of the pneumaticity.
We found that some of the synapomorphic
characters of derived carcharodontosaurids appear to be the
result of peramorphic heterochronies, as in the strongly
ornamented facial bones, and the single opening in the
anteroventral corner of the antorbital fossa in the maxilla.
carcharodontosaurids recorded in the Albian – Cenomanian of Gondwana are the youngest and most derived members of this
clade. Tyrannotitan chubutensis, from the Cerro Castan˜ o Member of Cerro Barcino Formation (Albian; Chubut Group),
Central Patagonia, Argentina, is of prime interest among Gondwanan carcharodontosaurids as it represents the oldest record
of the group. Here we offer a detailed osteological comparative description of the holotype and paratype of Tyrannotitan
chubutensis together with a new diagnosis of the species. The new information results in a better understanding of this taxon
and Carcharodontosauridae. Furthermore, a comparative study of the anatomy of the pectoral girdle of Giganotosaurus is
reinterpreted as very similar to that of Tyrannotitan and Mapusaurus. We also present a phylogenetic analysis of
Carcharodontosauridae that recovers Tyrannotitan as a derived carcharodontosaurid, being the sister group of the clade
formed by Giganotosaurus and Mapusaurus, all nested in the clade Giganotosaurini
Skorpiovenator bustingorryi is reported here. The
holotype was found in Late Cenomanian–Early Turonian
outcrops of NW Patagonia, Argentina. This new taxon is
deeply nested within a new clade of South American
abelisaurids, named Brachyrostra. Within brachyrostrans,
the skull shortening and hyperossification of the skull roof
appear to be correlated with a progressive enclosure of the
orbit, a set of features possibly related to shock-absorbing
capabilities. Moreover, the development of horn-like structures
and differential cranial thickening appear to be
convergently acquired within Abelisauridae. Based on the
similarities between Skorpiovenator and carcharodontosaurid
tooth morphology, we suggest that isolated teeth originally
referred as post-Cenomanian Carcharodontosauridae most
probably belong to abelisaurids.
consisting of 31 nominal species belonging to singleton taxa and six families: Abelisauridae, Noasauridae,
Carcharodontosauridae, Megaraptoridae nov. fam., Alvarezsauridae, and Unenlagiidae. They provide
anatomical information that allows improved interpretation of theropods discovered in other regions of
Gondwana. Abelisauroids are the best represented theropods in Patagonia. They underwent an evolutionary
radiation documented fromthe Early Cretaceous through to the latest Cretaceous, and are represented by the
clades Abelisauridae and Noasauridae. Patagonian carcharodontosaurids are known from three taxa (Tyrannotitan,
Giganotosaurus and Mapusaurus), as well as from isolated teeth, collected from Aptian to Cenomanian
beds. These allosauroids constituted the top predators during the mid-Cretaceous, during which
gigantic titanosaur sauropodswere the largest herbivores. Megaraptorans have become better documented
in recent years with the discovery of more complete remains. Megaraptor, Aerosteon and Orkoraptor have
been described from Cretaceous beds from Argentina, and these taxa exhibit close relationships with the
Aptian genera Australovenator, from Australia, and Fukuiraptor, from Japan. The Gondwanan megaraptorans
are gathered into the newfamily Megaraptoridae, and the Asiatic Fukuiraptor is recovered as the immediate
sister taxon of this clade. Although megaraptorans have been recently interpreted as members of Allosauroidea,
we present evidence that they are deeply nested within Coelurosauria. Moreover, anatomical
information supports Megaraptora as more closely related to the Asiamerican Tyrannosauridae than
thought. Megaraptorans improve our knowledge about the scarcely documented basal radiation of Gondwanan
coelurosaurs and tyrannosauroids as awhole. Information at hand indicates that SouthAmericawas a
cradle for the evolutionary radiation for different coelurosaurian lineages, including some basal forms (e.g.,
Bicentenaria, Aniksosaurus), megaraptorans, alvarezsaurids less derived than those of Laurasia, and unenlagiids,
revealing that Gondwanan coelurosaurs played sharply differing ecological roles, and that theywere
taxonomically as diverse as in the northern continents. The unenlagiids represent an endemic South
American clade that has been recently found to be more closely related to birds than to dromaeosaurid
theropods. Analysis of the theropod fossil record from Gondwana shows the highest peak of origination
index occurred during the AptianeAlbian and a less intense one in the Campanian time spans. Additionally,
peaks of extinction index are recognized for the Cenomanian and TuronianeConiacian time spans. In
comparison, the Laurasianpattern differs fromthat of Gondwana in the presence of an older extinction event
during the AptianeAlbian time-span and a high origination rate during the Cenomanian time-bin. Both
Laurasian and Gondwanan theropod records show a peak of origination rates during the Campanian.
the Candeleros Formation (Cenomanian), Neuquén Group, at Cabo Alarcón, Neuquén province,
Argentina. The analysis of this new specimen allows the re-‐‑interpretation of a previously described
pterosaur tibia founded at Los Catutos locality, Neuquén (MOZ 2280 P) as a proximal ulna. The
new material belongs to a medium-‐‑sized pterosaur, considerably larger than previously recorded
pterosaurs from this geological unit. The analysis of correlation between ulnar length-‐‑pes length in
well-‐‑known pterodactyloid pterosaurs shows that the new ulna matches well with the inferred size
of the Pteraichnus isp. trackmaker recorded from the same formation.
members are well-known from Jurassic and Cretaceous strata in Africa, Europe, North and South America. However,
Diplodocids were never certainly recognized from the Cretaceous or in any other southern land mass besides Africa. Here
we report a new sauropod, Leikupal laticauda gen. et sp. nov., from the early Lower Cretaceous (Bajada Colorada Formation)
of Neuque´n Province, Patagonia, Argentina. This taxon differs from any other sauropod by the presence of anterior caudal
transverse process extremely developed with lateroventral expansions reinforced by robust dorsal and ventral bars, very
robust centroprezygapophyseal lamina in anterior caudal vertebra and paired pneumatic fossae on the postzygapophyses
in anterior-most caudal vertebra. The phylogenetic analyses support its position not only within Diplodocidae but also as a
member of Diplodocinae, clustering together with the African form Tornieria, pushing the origin of Diplodocoidea to the
Middle Jurassic or even earlier. The new discovery represents the first record of a diplodocid for South America and the
stratigraphically youngest record of this clade anywhere.
observed in different anatomical views: Y-shaped (anterior view) and forked (lateral view). This research proposes
a classification combining information observed in anterior and lateral views. Four types of ‘Y-shaped’ and six types of
‘V-shaped’ chevrons were recognised. Complete chevron series in some eusauropods allows the comparison of topological
equivalent structures along the tail and also among taxa. A basal titanosaur from Argentina exhibits mid-caudal chevron
morphology in which more than one cranial and caudal process is present, arising from the distal blades as well as from the
proximal rami, a condition not seen before in a sauropod dinosaur. The morphological variability seen in sauropod chevrons
along the tail is in close relationship with the development and distribution of muscle. caudofemoralis longus, as seen in
extant crocodiles and as previously proposed for non-avian theropods and for caudal centra and transverse processes of
sauropod dinosaurs. Two new characters related to middle chevrons are proposed here, in which the transitional morphology
is described.
latex after removing mechanically the sediment filling of the cerebral cavity of the braincase, thereby
allowing the description of the endocranial anatomy of the specimen. The endocast was compared
with the other few known natural or artificial theropod endocasts, including the two species of the
African allosauroid species Carcharodontosaurus saharicus and C. idiguensis. As in Carcharodontosaurus,
the olfactory bulbs in Giganotosaurus are aligned with the forebrain, the midbrain is posteroventrally
inclined and the hindbrain is parallel but ventral to the forebrain, showing similarly angled
cephalic and pontine flexures. The cranial nerves and blood vessels have a similar disposition as in
Carcharodontosaurus saharicus. However, in Giganotosaurus there is only one branch for cranial
nerve XII, and cranial nerve XI has a separate internal opening from the vagus foramen (metotic
foramen). In C. saharicus, there is a separate opening as well, but it is anterior in position and
was probably utilized by cranial nerve IX. The length of the endocast of Giganotosaurus, including
the olfactory bulbs, is approximately 19 % longer than the endocast in Carcharodontosaurus
saharicus.