Osteology of Ornithopod Macrogryphosaurus gondwanicus (Dinosauria, Ornithischia) from the Upper Cretaceous of Patagonia, Argentina

Fil: Rozadilla, Sebastián. Laboratorio de Anatomía Comparada y Evolución de Los Vertebrados, Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; Argentina.Fil: Cruzado Caballero, Penélope. CONICET e Instituto de Investigación en Paleobiología y Geología, Sede Alto Valle-Valle Medio-Universidad Nacional de Río Negro; Argentina.Fil: Calvo, Jorge O. Grupo de Transferencia Proyecto Dino. Facultad de Ingeniería, Universidad Nacional del Comahue. Parque Natural Geo-Paleontologico Proyecto Dino; Argentina.Fil: Cruzado Caballero, Penélope. Universidad Nacional de Río Negro. Instituto de Investigación en Paleobiología y Geología. Río Negro, Argentina.Macrogryphosaurus gondwanicus is the largest Elasmaria (Dinosauria, Ornithischia) known up to the date, from the Upper Cretaceous of Patagonia. The present contribution provides a detailed description of Macrogryphosaurus anatomy based on the holotype and only known specimen. This dinosaur presents several unique features along its vertebral column that distinguishes it from other ornithopods: the neck is notably elongated by the acquisition of an additional cervical vertebra, having 10 cervical plus 14 dorsal vertebrae, being the number of dorsals minor than in other taxa, which usually have 16. This implies that Macrogryphosaurus represents a new ornithopod morphotype, with long neck and short thorax. Moreover, three autapomorphies are here added to the original diagnosis of Macrogryphosaurus: presence of poorly developed diapophyses in the cervical vertebrae, anterior and posterior processes on the boatshaped haemal arches, and a pubic foot in the postpubic process. The dorsoventral length of haemal arches indicate the ventral limit of the M. caudofemoralis longus and their posterior tapering so as the dorsal limit of the M. ilio-ischiocaudalis and its posterior ascension and dominance in the posterior-most portion of tail, resembling to the tail of some coelurosaur dinosaurs

Praeornis sharovi Rautian, 1978 a fossil feather from the early Late Jurassic of Kazakhstan

Since its original description as a feather belonging to a basal bird, the phylogenetic position of Praeornis sharovi was debated. It was considered as belonging to a bird, a cycad leaf, or as a ‘transitional’ integumentary structure between reptile scales and bird feathers. Recently, a basal enantiornithine bird was collected in Early Cretaceous beds of Brazil. This specimen shows very well-preserved rachis-dominated tail feathers with a very thick rachis and thick and rigid barbules. These features are present in Praeornis, suggesting that this fossil may be interpreted as the tail feather of a basal bird. In this way, Praeornis constitutes one of the oldest records of rachis-dominated feathers in the world. Rachis-dominated tail feathers, including that of Praeornis appear to be rigid paired structures not performed for aerodynamical purposes, suggesting that may be important in body balance

A new small-bodied ankylosaurian dinosaur from the Upper Cretaceous of North Patagonia (Río Negro Province, Argentina)

The most representative ankylosaurian remains from Argentina have been found in sediments of the Allen Formation (Campanian–Maastrichtian) in Salitral Moreno, Río Negro Province. Several authors have discussed the identity and history of these remains. In this study, we review all published material along with some new remains in order to summarize all the knowledge about these ankylosaurs. Previously published material includes a tooth, dorsal and anterior caudal vertebrae, a femur and several osteoderms. The new remains include synsacral and caudal elements, a partial femur and osteoderms. The anatomy of the tooth, the synsacrum, the mid-caudal vertebra, the femur and the osteoderms, and the histology of the post-cervical osteoderms, support a nodosaurid identification, as proposed in previous descriptions of the Salitral Moreno material. Patagopelta cristata gen. et sp. nov. is a new nodosaurid ankylosaur characterized by the presence of unique cervical half-ring and femoral anatomies, including high-crested lateral osteoderms in the half rings and a strongly developed muscular crest in the anterior surface of the femur. The ∼2 m body length estimated for Patagopelta is very small for an ankylosaur, comparable with the dwarf nodosaurid Struthiosaurus. We recovered Patagopelta within Nodosaurinae, related to nodosaurids from the ‘mid’-Cretaceous of North America, contrasting the previous topologies that related this material with Panoplosaurini (Late Cretaceous North American nodosaurids). These results support a palaeobiogeographical context in which the nodosaurids from Salitral Moreno, Argentina, are part of the allochthonous fauna that migrated into South America during the late Campanian as part of the First American Biotic Interchange. https://zoobank.org/urn:lsid:zoobank.org:pub:FBA24443-F365-49FD-A959-10D2848C2400.Fil: Riguetti, Facundo Javier. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Maimónides. Centro de Ciencias Naturales, Ambientales y Antropológicas; ArgentinaFil: Pereda Suberbiola, Xabier. Universidad del País Vasco; EspañaFil: Ponce, Denis Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación en Paleobiología y Geología; ArgentinaFil: Salgado, Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación en Paleobiología y Geología; ArgentinaFil: Apesteguía, Sebastián. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Maimónides. Centro de Ciencias Naturales, Ambientales y Antropológicas; ArgentinaFil: Rozadilla, Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Arbour, Victoria. University of Victoria; Canad

Phylogenetic reassessment of <i>Pisanosaurus mertii</i> Casamiquela, 1967, a basal dinosauriform from the Late Triassic of Argentina

<p><i>Pisanosaurus mertii</i> was originally described on the basis of an incomplete skeleton from the early Late Triassic (Carnian) of northern Argentina. It is consistently regarded by most authors as a very basal ornithischian, the sister group of remaining members of the clade. The referral to Ornithischia is based mainly on tooth-bearing bones and tooth morphology. On the other hand, the postcranium is recognized as strikingly plesiomorphic for ornithischians, and even for dinosaurs. The recent description of non-dinosaurian dinosauriforms of the clade Silesauridae having ornithischian-like dentition invites a review of the phylogenetic affinities of <i>Pisanosaurus</i>. In this regard, an overview of the holotype specimen allows a reanalysis of previous anatomical interpretations of this taxon. The phylogenetic analysis presented here suggests that <i>Pisanosaurus</i> may be better interpreted as a member of the non-dinosaurian Silesauridae. It shares with silesaurids reduced denticles on the teeth, teeth fused to maxilla and dentary bone, sacral ribs shared between two sacral vertebrae, lateral side of proximal tibia with a fibular flange, and dorsoventrally flattened pedal ungual phalanges. The present analysis indicates that <i>Pisanosaurus</i> should be removed from the base of the Ornithischia and should no longer be considered the oldest representative of this dinosaurian clade.</p

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., from the Upper Jurassic (Tithonian) Toqui Formation of southern Chile. The new taxon constitutes one of the few records of non-pelagic Jurassic crocodyliforms for the entire South American continent. Burkesuchus was found on the same levels that yielded titanosauriform and diplodocoid sauropods and the herbivore theropod Chilesaurus diegosuarezi, thus expanding the taxonomic composition of currently poorly known Jurassic reptilian faunas from Patagonia. Burkesuchus was a small-sized crocodyliform (estimated length 70 cm), with a cranium that is dorsoventrally depressed and transversely wide posteriorly and distinguished by a posteroventrally flexed wing-like squamosal. A well-defined longitudinal groove runs along the lateral edge of the postorbital and squamosal, indicative of a anteroposteriorly extensive upper earlid. Phylogenetic analysis supports Burkesuchus as a basal member of Mesoeucrocodylia. This new discovery expands the meagre record of non-pelagic representatives of this clade for the Jurassic Period, and together with Batrachomimus, from Upper Jurassic beds of Brazil, supports the idea that South America represented a cradle for the evolution of derived crocodyliforms during the Late Jurassic.We are grateful to C. Alsina, M. Milani, N. Chimento, M. Aranciaga, F. Brissón-Egli, G. Muñoz, and S. Miner for field assistance and technical preparation of Burkesuchus specimens. Special thanks to D. Pol for his comments on an early version of the manuscript. We are indebted to the Agencia Nacional de Promoción Científica y Tecnológica (PICT 2010-066 to F.E.N.), Fondo Nacional de Desarrollo Científico y Tecnológico (no. 1121140 to M.S. the Proyect FIC N° 40000501 to M. S., Conselho Nacional de Desenvolvimento Científico e Tecnológico), National Geographic (NGS Grant CP-075ER-17 to S.R.) and Mr. Coleman Burke for financial support. Special thanks to the editor J. O´Connor and two anonymous reviewers for their enlightening comments which greatly improved the quality of the present contribution