FIRST FOSSIL RECORD OF ASPREDINIDAE: A NEW SPECIES FROM THE LATE MIOCENE OF NORTHEASTERN ARGENTINA.

This study aims to describe a new fossil species of the extant aspredinid genus Bunocephalus. The new species is represented by a nearly complete skull and pectoral girdle coming from late Miocene Ituzaingó Formation beds of Paraná City, Entre Ríos Province, Argentina. The specimen constitutes the first fossil record for the genus and the family Aspredinidae.

A new carcharodontosaurid specimen sheds light on the anatomy of South American giant predatory dinosaurs.

Carcharodontosaurids were gigantic terrestrial dinosaurs and top predators of dinosaur faunas in Gondwanan landmasses during the "Mid"-Cretaceous Period. Despite their wide geographical and stratigraphical distribution, essential parts of their anatomy are still poorly known. The present contribution aims to describe a new partial skeleton of the carcharodontosaurid Taurovenator violantei, which was previously known only by an isolated postorbital bone coming from Cenomanian-Turonian beds of northern Patagonia, Argentina.

A large therian mammal from the Late Cretaceous of South America.

Theria represent an extant clade that comprises placental and marsupial mammals. Here we report on the discovery of a new Late Cretaceous mammal from southern Patagonia, Patagomaia chainko gen. et sp.

Comments on the pelvic girdle anatomy of Lagerpeton chanarensis Romer, 1971 (Archosauria) and its implications on the posture and gait of early pterosauromorphs.

Lagerpeton chanarensis is an early avemetatarsalian from the lower Carnian (lowermost Upper Triassic) levels of the Chañares Formation, La Rioja Province, Argentina. Lagerpeton and its kin were traditionally interpreted as dinosaur precursors of cursorial habits, with a bipedal posture and parasagittal gait. Some authors also speculated saltatorial capabilities for this genus.

How many species of Sturisoma (Siluriformes: Loricariinae) inhabit the La Plata Basin?

The aim of the present contribution is to review the taxonomy of the loricariid Sturisoma in the La Plata basin. The original description of the species S. barbatum is analyzed and compared to Regans later description of S.

A Maastrichtian insect assemblage from Patagonia sheds light on arthropod diversity previous to the K/Pg event.

Insect faunas from the latest Cretaceous are poorly known worldwide. Particularly, in the Southern Hemisphere, there is a gap regarding insect assemblages in the Campanian-Maastrichtian interval. Here we present an insect assemblage from the Maastrichtian Chorrillo Formation, southern Argentina, represented by well-preserved and non-deformed, chitinous microscopic remains including head capsules, wings and scales.

New reptile shows dinosaurs and pterosaurs evolved among diverse precursors.

Dinosaurs and pterosaurs have remarkable diversity and disparity through most of the Mesozoic Era. Soon after their origins, these reptiles diversified into a number of long-lived lineages, evolved unprecedented ecologies (for example, flying, large herbivorous forms) and spread across Pangaea. Recent discoveries of dinosaur and pterosaur precursors demonstrated that these animals were also speciose and widespread, but those precursors have few if any well-preserved skulls, hands and associated skeletons.

First monotreme from the Late Cretaceous of South America.

Monotremata is a clade of egg-lying mammals, represented by the living platypus and echidnas, which is endemic to Australia, and adjacent islands. Occurrence of basal monotremes in the Early Cretaceous of Australia has led to the consensus that this clade originated on that continent, arriving later to South America. Here we report on the discovery of a Late Cretaceous monotreme from southern Argentina, demonstrating that monotremes were present in circumpolar regions by the end of the Mesozoic, and that their distinctive anatomical features were probably present in these ancient forms as well.

Wing osteology, myology, and function of Rhea americana (Aves, Rheidae).

The Greater Rhea (Rhea americana, Rheidae) is a flightless paleognath with a wide geographical distribution in South America. The morphology of its shoulder girdle and wings are different from those of flying birds and some characteristics are similar to basal birds and paravian theropods. We present a detailed osteological, myological, and functional study of the shoulder and the wing of the Greater Rhea.

A large Megaraptoridae (Theropoda: Coelurosauria) from Upper Cretaceous (Maastrichtian) of Patagonia, Argentina.

Megaraptora is a theropod clade known from former Gondwana landmasses and Asia. Most members of the clade are known from the Early to Late Cretaceous (Barremian-Santonian), with Maastrichtian megaraptorans known only from isolated and poorly informative remains. The aim of the present contribution is to describe a partial skeleton of a megaraptorid from Maastrichtian beds in Santa Cruz Province, Argentina.

Fossil fishes and anurans from the Miocene of Rio Chico and Cerro Zeballos, Chubut Province, Argentina.

The fossil record of freshwater fishes and anurans from the Miocene in Patagonia is relatively patchy, a large number of specimens remaining undescribed. The aim of the present contribution is to describe a fossil association of percomorphacean fishes and calyptocephalellid anurans from the early to late Miocene Collón Curá Formation, at Chubut province, Patagonia, Argentina. In spite of being represented by several specimens, both anurans and fishes show a very low taxonomic diversity.

New specimens provide insights into the anatomy of the dinosauriform Lewisuchus admixtus Romer, 1972 from the upper Triassic levels of the Chañares Formation, NW Argentina.

Lewisuchus admixtus is an early dinosauriform described by Alfred Romer in 1972 on the basis of a single, incomplete skeleton, collected in lower Upper Triassic rocks of the renowned Chañares Formation, at the Los Chañares type-locality, La Rioja Province, north-western Argentina. Recent field explorations to the type-locality resulted in the discovery of two partial articulated skeletons, which provide significant novel information. The cranial bones, presacral series, femur, tibia, and proximal tarsals of the new specimens match the preserved overlapping anatomy of the holotype and previously referred specimens of L.

New transitional fossil from late Jurassic of Chile sheds light on the origin of modern crocodiles.

We describe the basal mesoeucrocodylian Burkesuchus mallingrandensis nov. gen. et sp.

Osteology of Unenlagia comahuensis (Theropoda, Paraves, Unenlagiidae) from the Late Cretaceous of Patagonia.

Unenlagia comahuensis was originally described as a phylogenetic link between nonavian dinosaurs and birds. Later it was interpreted by some authors as belonging to the deinonychosaurian clade Dromaeosauridae, and more recently as phylogenetically closer to birds than to dromaeosaurids. The only known specimen is represented by an incomplete skeleton, including vertebrae, incomplete scapular girdle, pelvis, and limbs, coming from Upper Cretaceous beds of Neuquén province, Patagonia, Argentina.

Enigmatic dinosaur precursors bridge the gap to the origin of Pterosauria.

Pterosaurs were the first vertebrates to evolve powered flight and comprised one of the main evolutionary radiations in terrestrial ecosystems of the Mesozoic era (approximately 252-66 million years ago), but their origin has remained an unresolved enigma in palaeontology since the nineteenth century. These flying reptiles have been hypothesized to be the close relatives of a wide variety of reptilian clades, including dinosaur relatives, and there is still a major morphological gap between those forms and the oldest, unambiguous pterosaurs from the Upper Triassic series. Here, using recent discoveries of well-preserved cranial remains, microcomputed tomography scans of fragile skull bones (jaws, skull roofs and braincases) and reliably associated postcrania, we demonstrate that lagerpetids-a group of cursorial, non-volant dinosaur precursors-are the sister group of pterosaurs, sharing numerous synapomorphies across the entire skeleton.

New record of a Mesozoic gondwanatherian mammaliaform from Southern Patagonia.

Gondwanatheria is an enigmatic mammaliaform clade distributed in the Cretaceous and Paleogene of South America, Africa, Madagascar, India and Antarctica. The Mesozoic record in South America is restricted to the Latest Cretaceous of Río Negro and Chubut provinces, Argentina and Magallanes Region of southern Chile. The aim of the present contribution is to describe a new specimen of gondwanatherian mammaliaforms from beds belonging to the Maastrichtian Chorrillo Formation, cropping out 30 km SW of El Calafate, Santa Cruz Province, Argentina.

First fossil of the Giant Armored Catfish Acanthicus (Siluriformes, Loricariidae) from the Late Miocene of Entre Ríos Province, Argentina.

Loricariidae is a very diverse lineage of Neotropical fishes, being the most speciose family of the order Siluriformes. However, the loricariid fossil record is still very sparse. The aim of the present contribution is to describe in detail several bones belonging to the loricariid genus Acanthicus coming from late Miocene beds located at the Paraná River cliffs, Entre Ríos province, Argentina.

Phylogenetic tree of Litopterna and Perissodactyla indicates a complex early history of hoofed mammals.

The Litopterna is an extinct clade of endemic South American ungulates that range from Paleocene up to late Pleistocene times. Because of their unique anatomy, litopterns are of uncertain phylogenetic affinities. However, some nineteenth century authors, considered litopterns as related to perissodactyl ungulates, a hypothesis recently sustained by molecular data.

A Pleistocene freshwater ichthyofaunal assemblage from central Argentina: What kind of fishes lived in the Pampean lagoons before the extinction of the megafauna?

This study contributes to the knowledge of continental fishes recovered from sedimentary successions corresponding to the Bonaerean Stage/Age (late mid-Pleistocene) in the locality of Centinela del Mar, General Alvarado County, Buenos Aires province, Argentina. At this site we describe fossil fishes from a palaeolagoon, including Corydoras sp., Pimelodella sp.

New theropod dinosaur from the Upper Cretaceous of Patagonia sheds light on the paravian radiation in Gondwana.

The fossil record of basal paravians in Gondwana is still poorly known, being limited to the Cretaceous unenlagiids from South America and the problematic Rahonavis from Madagascar. Here we report on a new paravian from the Cenomanian-Turonian (Late Cretaceous) of Río Negro province, NW Patagonia, Argentina. The new taxon exhibits a derived bird-like morphology of the forelimbs (e.

A rostral neurovascular system in the mosasaur Taniwhasaurus antarcticus.

Mosasaurs were a cosmopolitan group of marine squamate reptiles that lived during the Late Cretaceous period. Tylosaurinae mosasaurs were characterized for having an edentulous rostrum anterior to the premaxillary teeth. External morphology of the snout of the tylosaurine Taniwhasaurus antarcticus from the Upper Cretaceous beds at James Ross Island (Antarctic Peninsula) shows a complex anatomy with diverse large foramina and bone sculpture.

Review of the enigmatic 'shark', Platyacrodus unicus Ameghino, 1935, from the Paleocene of Patagonia, Argentina: a history of palaeontologists, sharks and crabs.

Platyacrodus unicus Ameghino, 1935, was described as an enigmatic shark probably related to the clade Heterodontidae. This species was described based on a single, small crushing tooth-like element coming from the "Salamancan" (Danian) of the Western Río Chico locality, Chubut province, Patagonia, Argentina. The holotype and only known specimen was never figured and only briefly characterized by its original describer Florentino Ameghino.

Vegaviidae, a new clade of southern diving birds that survived the K/T boundary.

The fossil record of Late Cretaceous-Paleogene modern birds in the Southern Hemisphere includes the Maastrichtian Neogaeornis wetzeli from Chile, Polarornis gregorii and Vegavis iaai from Antarctica, and Australornis lovei from the Paleogene of New Zealand. The recent finding of a new and nearly complete Vegavis skeleton constitutes the most informative source for anatomical comparisons among Australornis, Polarornis, and Vegavis. The present contribution includes, for the first time, Vegavis, Polarornis, and Australornis in a comprehensive phylogenetic analysis.