A new species of Comahuesuchus Bonaparte, 1991 (Crocodyliformes: Notosuchia) from the Upper Cretaceous of Neuquén, Lake Barreales, Patagonia, Argentina.

Notosuchian crocodyliforms were major components of the South American Cretaceous biota and, for over 125 years, paleontological fieldwork in this continent recovered several well-preserved fossils of these animals. They are largely recognized for terrestrial life and specialized feeding habits, frequently presenting bizarre taxa such as Comahuesuchus. A new species, Comahuesuchus bonapartei n. sp. (MUCPv 597; cast MN), is described from geological strata of Sierra Barrosa Formation (Upper Turonian) and Portezuelo Formation (Lower Coniacian) of Lake Barreales, Patagonia, Argentina. The new fossil comprises a right dentary bone that shares important and unique anatomical features with specimens of Comahuesuchus brachybuccalis, such as the presence of a well-marked shelf on the lateral surface of the bone; a flat, low, and wide mandibular symphysis; an enlarged, labiolingually compressed caniniform tooth at caudal position in the dentary; the presence of serrated mesial and distal carinae in the caniniform with a faceted labial surface, and the absence or extremely reduction in number of the postcaniniform dentition. C. bonapartei differs from C. brachybuccalis in having individual dentary alveoli, rather a dentition set in groove. Phylogenetic analyses support a sister-relationship between both species, which are well nested within notosuchians.

Reconstruction of the pectoral girdle and forelimb musculature of Megaraptora (Dinosauria: Theropoda).

Megaraptora is a group of enigmatic, carnivorous non-avian theropod dinosaurs from the Cretaceous of Asia, Australia, and especially South America. Perhaps the most striking aspect of megaraptoran morphology is the large, robustly constructed forelimb that, in derived members of the clade, terminates in a greatly enlarged manus with hypertrophied, raptorial unguals on the medialmost two digits and a substantially smaller ungual on digit III. The unique forelimb anatomy of megaraptorans was presumably associated with distinctive functional specializations; nevertheless, its paleobiological significance has not been extensively explored. Here we draw from observations of the pectoral girdle and forelimb skeletons of Megaraptora and myological assessments of other archosaurian taxa to provide a comprehensive reconstruction of the musculature of this anatomical region in these singular theropods. Many muscle attachment sites on megaraptoran forelimb bones are remarkably well developed, which in turn suggests that the muscles themselves were functionally significant and important to the paleobiology of these theropods. Furthermore, many of these attachments became increasingly pronounced through megaraptoran evolutionary history, being substantially better developed in derived taxa such as Australovenator wintonensis and especially Megaraptor namunhuaiquii than in early branching forms such as Fukuiraptor kitadaniensis. When considered alongside previous range of motion hypotheses for Australovenator, our results indicate that megaraptorans possessed a morphologically and functionally specialized forelimb that was capable of complex movements. Notable among these were extensive extension and flexion, particularly in the highly derived manus, as well as enhanced humeral protraction, attributes that very probably aided in prey capture.

Re-description of the braincase of the rebbachisaurid sauropod Limaysaurus tessonei and novel endocranial information based on CT scans.

CT scans of the type braincase of Limaysaurus tessonei (MUCPv-205) allowed the first study of the endocranial cavities (brain and inner ear) for this South American taxon. Comparisons of the cranial endocast of L. tessonei with other sauropods indicate that 1) South American rebbachisaurids are more similar to each other than to Nigersaurus, and 2) certain association of traits are present in all known rebbachisaurid cranial endocasts, such as lack of an enlarged dorsal expansion, poorly laterally projected cerebral hemispheres, presence of a small flocculus of the cerebellum, markedly long passage for the facial nerve (CN VII), markedly inclined pituitary, and presence of a passage for the basilar artery communicating the floor of the endocranial cavity and the pituitary fossa. The relatively enlarged olfactory region indicates that smell was an important sense for this group of dinosaurs, suggesting different olfactory capabilities when compared to coeval titanosaurs.

Baalsaurus mansillai gen. et sp. nov. a new titanosaurian sauropod (Late Cretaceous) from Neuquén, Patagonia, Argentina.

We describe a dentary of a new titanosaur sauropod, Baalsaurus mansillai, gen. et sp. nov. from the Late Cretaceous of Patagonia, Argentina. The material comes from the Portezuelo Formation, Neuquén Group. Titanosaur sauropods lower jaws are scarce and only nine taxa with dentaries have been described. There are two types of morphology in titanosaur dentaries; "L" shaped or "U" shaped based on the shape, without a phylogenetic issue. In this paper; we recognize a new taxa, Baalsaurus mansillai, represented by an "L" shaped dentary with three apomorphic characters that are not present in other taxa: dentary alveoli with 10 teeth in the anterior ramus, a ventrally and anteriorly inclined symphysis and a wide ventral Meckelian groove surrounded by a thin lamina that forms a keel on the ventral border of the dentary.

New azhdarchoid pterosaur (Pterosauria, Pterodactyloidea) with an unusual lower jaw from the Portezuelo Formation (Upper Cretaceous), Neuquén Group, Patagonia, Argentina.

A new azhdarchoid pterosaur from the Upper Cretaceous of Patagonia is described. The material consists of an incomplete edentulous lower jaw that was collected from the upper portion of the Portezuelo Formation (Turonian-Early Coniacian) at the Futalognko site, northwest of Neuquén city, Argentina. The overall morphology of Argentinadraco barrealensis gen. et sp. nov. indicates that it belongs to the Azhdarchoidea and probable represents an azhdarchid species. The occlusal surface of the anterior portion is laterally compressed and shows blunt lateral margins with a medial sulcus that are followed by two well-developed mandibular ridges, which in turn are bordered laterally by a sulcus. The posterior end of the symphysis is deeper than in any other azhdarchoid. This unique construction of the lower jaw suggests the existence of an elaborate interlocking mechanism with the upper jaw. Furthermore, although speculative, it is advocated here that Argentinadraco barrealensis might have used the lower jaw to obtain its prey by cutting or ploughing through unconsolidated sediment in shallow waters, a feeding behavior not previously proposed for pterosaurs.

New azhdarchoid pterosaur (Pterosauria, Pterodactyloidea) with an unusual lower jaw from the Portezuelo Formation (Upper Cretaceous), Neuquén Group, Patagonia, Argentina

ABSTRACT A new azhdarchoid pterosaur from the Upper Cretaceous of Patagonia is described. The material consists of an incomplete edentulous lower jaw that was collected from the upper portion of the Portezuelo Formation (Turonian-Early Coniacian) at the Futalognko site, northwest of Neuquén city, Argentina. The overall morphology of Argentinadraco barrealensis gen. et sp. nov. indicates that it belongs to the Azhdarchoidea and probable represents an azhdarchid species. The occlusal surface of the anterior portion is laterally compressed and shows blunt lateral margins with a medial sulcus that are followed by two well-developed mandibular ridges, which in turn are bordered laterally by a sulcus. The posterior end of the symphysis is deeper than in any other azhdarchoid. This unique construction of the lower jaw suggests the existence of an elaborate interlocking mechanism with the upper jaw. Furthermore, although speculative, it is advocated here that Argentinadraco barrealensis might have used the lower jaw to obtain its prey by cutting or ploughing through unconsolidated sediment in shallow waters, a feeding behavior not previously proposed for pterosaurs.

A gigantic new dinosaur from Argentina and the evolution of the sauropod hind foot.

Titanosauria is an exceptionally diverse, globally-distributed clade of sauropod dinosaurs that includes the largest known land animals. Knowledge of titanosaurian pedal structure is critical to understanding the stance and locomotion of these enormous herbivores and, by extension, gigantic terrestrial vertebrates as a whole. However, completely preserved pedes are extremely rare among Titanosauria, especially as regards the truly giant members of the group. Here we describe Notocolossus gonzalezparejasi gen. et sp. nov. from the Upper Cretaceous of Mendoza Province, Argentina. With a powerfully-constructed humerus 1.76 m in length, Notocolossus is one of the largest known dinosaurs. Furthermore, the complete pes of the new taxon exhibits a strikingly compact, homogeneous metatarsus--seemingly adapted for bearing extraordinary weight--and truncated unguals, morphologies that are otherwise unknown in Sauropoda. The pes underwent a near-progressive reduction in the number of phalanges along the line to derived titanosaurs, eventually resulting in the reduced hind foot of these sauropods.

A new small deinonychosaur (Dinosauria: Theropoda) from the Late Cretaceous of Patagônia, Argentina.

Here we report on a new small deinonychosaurian theropod, Pamparaptor micros gen. et sp. nov., from the Late Cretaceous of Patagônia, Argentina. Pamparaptor micros exhibits a pedal structure previously unknown among South Américan deinonychosaurians. The new material provides new evidence about the morphology and taxonomic diversity of Patagônian deinonychosaurs. Pamparaptor is the smaller non-avialae Patagônian deinonychosaur, probably with about 0.50-0.70 meters, long. The pedal construction resembles, that of Troodontid or basal Dromaeosaurids. Nevertheless, up to now, we considered Pamparaptor a peculiar Patagônian Dromaeosaurid with troodontid-like pes.

A new small deinonychosaur (Dinosauria: Theropoda) from the Late Cretaceous of Patagônia, Argentina

Here we report on a new small deinonychosaurian theropod, Pamparaptor micros gen. et sp. nov., from the Late Cretaceous of Patagônia, Argentina. Pamparaptor micros exhibits a pedal structure previously unknown among South Américan deinonychosaurians. The new material provides new evidence about the morphology and taxonomic diversity of Patagônian deinonychosaurs. Pamparaptor is the smaller non-avialae Patagônian deinonychosaur, probably with about 0.50-0.70 meters, long. The pedal construction resembles, that of Troodontid or basal Dromaeosaurids. Nevertheless, up to now, we considered Pamparaptor a peculiar Patagônian Dromaeosaurid with troodontid-like pes.

Aqui reportamos um novo pequeno teropodo deinonicosauriano, Pamparaptor micros gen. et sp. nov. do Cretacéo Superior da Patagônia, Argentina. Pamparaptor exibe uma estrutura pedal previamente desconhecida entre os deinonicosaurídeos da América do Sul. O novo material fornece uma nova evidencia sobre a diversidade morfológica e taxonômica dos deinonicosaurídeos patagonicos. O Paparaptor e o menor deinonicosaurídeo não-aviano patagonico, medindo provavelmente entre 0,50-0,70 metros de comprimento. A construção pedal lembra aquela de Troodontídeos ou Dromaeosaurídios basais. Entretanto, ate agora, consideramos Paparaptor um Dromaeosaurídeo patagonico peculiar com o pe similar ao de Troodontídeos.

A bizarre Cretaceous theropod dinosaur from Patagonia and the evolution of Gondwanan dromaeosaurids.

Fossils of a predatory dinosaur provide novel information about the evolution of unenlagiines, a poorly known group of dromaeosaurid theropods from Gondwana. The new dinosaur is the largest dromaeosaurid yet discovered in the Southern Hemisphere and depicts bizarre cranial and postcranial features. Its long and low snout bears numerous, small-sized conical teeth, a condition resembling spinosaurid theropods. Its short forearms depart from the characteristically long-armed condition of all dromaeosaurids and their close avian relatives. The new discovery amplifies the range of morphological disparity among unenlagiines, demonstrating that by the end of the Cretaceous this clade included large, short-armed forms alongside crow-sized, long-armed, possibly flying representatives. The new dinosaur is the youngest record of dromaeosaurids from Gondwana and represents a previously unrecognized lineage of large predators in Late Cretaceous dinosaur faunas mainly dominated by abelisaurid theropods.

A new Cretaceous terrestrial ecosystem from Gondwana with the description of a new sauropod dinosaur.

A unique site at the northern area of Patagonia (Neuquén, Argentina) reveals a terrestrial ecosystem preserved in a detail never reported before in a Late Cretaceous deposit. An extraordinary diversity and abundance of fossils was found concentrated in a 0.5 m horizon in the same quarry, including a new titanosaur sauropod, Futalognkosaurus dukei n.gen., n.sp, which is the most complete giant dinosaur known so far. Several plant leaves, showing a predominance of angiosperms over gymnosperms that likely constituted the diet of F. dukei were found too. Other dinosaurs (sauropods, theropods, ornithopods), crocodylomorphs, pterosaurs, and fishes were also discovered, allowing a partial reconstruction of this Gondwanan continental ecosystem.

A new Cretaceous terrestrial ecosystem from Gondwana with the description of a new sauropod dinosaur

A unique site at the northern area of Patagonia (Neuquén, Argentina) reveals a terrestrial ecosystem preserved in a detail never reported before in a Late Cretaceous deposit. An extraordinary diversity and abundance of fossils was found concentrated in a 0.5 m horizon in the same quarry, including a new titanosaur sauropod, Futalognkosaurus dukei n.gen., n.sp, which is the most complete giant dinosaur known so far. Several plant leaves, showing a predominance of angiosperms over gymnosperms that likely constituted the diet of F. dukei were found too. Other dinosaurs (sauropods, theropods, ornithopods), crocodylomorphs, pterosaurs, and fishes were also discovered, allowing a partial reconstruction of this Gondwanan continental ecosystem.

Um depósito fóssil na região norte da Patagônia (Neuquén, Argentina) revela um ecossistema nunca antes registrado a este nível de detalhes em depósitos do Cretáceo Superior. Uma diversidade e abundância extraordinária de fósseis encontra-se concentrada em uma camada de 0,5 m no mesmo sítio, incluindo um novo saurópodo titanossaurídeo, Futalognkosaurus dukei n. gen, n. sp., que é o mais completo dinossauro gigante encontrado até a presente data. Foram descobertas váriasfolhas de plantas indicando a predominância de angiospermas sobre gimnospermas que possivelmente formavam a base da dieta de F. dukei. Outros dinossauros (saurópodes, terópodes, ornitópodes), crocodilomorfos, pterossauros e peixes foram também encontrados possibilitando a reconstrução parcialdeste ecossistema continental do Gondwana.

Description of a sauropod dinosaur braincase from the Late Cretaceous Rio Colorado Subgroup, Patagonia.

The fossil record of cranial material from titanosaurid sauropods is very poor and no complete skull has been described so far. Here we describe a new braincase (MUCPv-334) that was recovered from reddish sandstones of the Rio Colorado Subgroup (Late Cretaceous) of the region of Bajo del Añelo, approximately 20 km north of the town Añelo (Neuquén Province, Argentina). This specimen is attributed to the Titanosauridae based on the ventrally projected basipterygoid processes, a common condition shared by other titanosaurids. The robustness of MUCPv-334 together with an unusually expanded crista prootica and the presence of an anterior prolongation of the parasphenoid reaching the basal tubera were not reported in other members of the Titanosauridae, indicating a larger diversity in the braincase morphology of this sauropod clade than previously thought.

Description of a sauropod dinosaur braincase (Titanosauridae) from the Late Cretaceous Rio Colorado Subgroup, Patagonia

O registro fóssil de elementos cranianos de titanossaurídeos é escasso, sendo que nenhum crânio completo foi descrito até o momento. Neste trabalho descrevemos um novo basicrânio (MUCPv-334) procedente de camadas avermelhadas do Subgrupo Rio Colorado (CretáceoSuperior) que afloram na região Bajo del Añelo, situada aproximadamente a 20 km norte da cidade Añelo (Província de Neuquén, Argentina). A presença de processos do basipterigoide direcionados ventralmente sugere que este exemplar represente um Titanosauridae. A robustez do basicrânio aliada à extensa crista proótica e a presença de uma prolongação do parasphenoide chegando até os basal tubera nunca tinham sido reportados em outros Titanosauridae, indicando que este clado de saurópodes possuía uma diversidade maior na morfologia do basicrânio do que se supunha.