DIVERSITY OF CROCODYLIFORMES IN THE UPPER CRETACEOUS OF RINCÓN DE LOS SAUCES REGION (NORTHERN OF NEUQUÉN PROVINCE, PATAGONIA, ARGENTINA)

FRANCISCO BARRIOS; LEONARDO S. FILIPPI; ARIANA PAULINA CARABAJAL; PENÉLOPE CRUZADO-CABALLERO; KAREN ULLOA-GUAIQUIN; SARA GARCÍA; JAVIER GONZÁLEZ-DIONIS; FLAVIO BELLARDINI; FEDERICO A. GIANECHINI; ALBERTO C. GARRIDO; EMANUEL SECULI PEREYRA; MARÍA LUCÍA BALARINO; ELENA PREVITERA; ARIEL H. MÉNDEZ

Salta

Congreso; Reunión de Comunicaciones de la Asociación Paleontológica Argentina; 2022

The diversity of the Upper Cretaceous (Cenomanian to Maastrichtian) crocodyliforms in Argentina is represented byseveral families of notosuchians (Notosuchidae, Comahuesuchidae, Baurusuchidae, Peirosauridae), and basalmesoeucrocodylian taxa. Most species (such as Neuquensuchus universitas, Notosuchus terrestris, Comahuesuchusbrachybuccalis, Cynodontosuchus rothi, Wargosuchus australis, Lomasuchus palpebrosus, Gasparinisuchus peirosauroides,Bayomesasuchus hernandezi, Patagosuchus anieliensis, and Barrosasuchus neuquenianus) were recovered from theprovince of Neuquén (Patagonia, Argentina). From the northern of the province, at the Rincón de los Sauces regionthe species Pehuenchesuchus enderi and Kinesuchus overoi were described. Field work carried on in recent years in theregion provided numerous crocodyliforms remains such as teeth, cranial and postcranial (osteoderms, vertebraeand appendicular) elements. Here, we provide a revision of the crocodyliforms remains in light of new findingshoused in the Museo Municipal Argentino Urquiza (MAU). Many of this fossil record is from the Cerro Overo-LaInvernada, Puesto Hernández, Puesto Narambuena and Cañadon Río Seco localities from levels of the Plottier(Upper Coniacian), Bajo de la Carpa (Santonian) and Anacleto (Lower Campanian) formations. In many cases thefossils are isolated and/or articulated fragments. Osteoderms are abundant with ornamentation based insubcircular pits, and a keel marked or not (e.g. MAU-Pv-LE-619, MAU-Pv-CO-692 to 695, 699 and 701). In secondorder in abundance are conical teeth crowns (caniniforms and molariforms) with denticulated carinae (e.g. MAU-Pv-CO-696 to 698, and 700). Postcranial remains comprise some complete vertebrae, neural arch and amphycelicvertebral body, both cervical, thoracic, lumbar, sacral and caudal (e.g. MAU-Pv-CO-584, 674). Appendicular elementsinclude proximal and/or distal epiphysis (both humerus, femur and tibia) and pelvic bones (e.g. MAU-Pv-CO-584 cf.Kinesuchus and 676 to 678). As for the cranial remains, relatively complete skull roof and temporal elements werefound (e.g. MAU-Pv-CO-632 and 686). Some mandibular fragments correspond to articular (as articular, surangularand angular bones; MAU-Pv-CO-690) and symphyseal (dentary and splenial bones; MAU-Pv-CO-583 Kinesuchusholotype, and 680) regions. A relatively complete and articulated tail including vertebrae and osteoderms was foundas well (e.g. MAU-Pv-PH-437, MAU-Pv-LI-691). All the mentioned crocodyliforms remains are assigned toPeirosauridae, except MAU-Pv-N-280 that could belong to a derived notosuchian. This shows the dominance of thepeirosaurids in the paleoenviroment of the region for the Upper Cretaceous (Coniacian to Santonian age mainly) incontrast with others notosuchians groups (such as notosuchids or baurusuchids).