Diversity of crocodyliformes in the Upper Cretaceous of Rincón de los Sauces region (Northern of Neuquén province, Patagonia, Argentina)

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

Salta

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

Asociación Paleontológica Argentina

The diversity of the Upper Cretaceous (Cenomanian to Maastrichtian) crocodyliforms in Argentina is represented by several families of notosuchians (Notosuchidae, Comahuesuchidae, Baurusuchidae, Peirosauridae), and basal mesoeucrocodylian taxa. Most species (such as Neuquensuchus universitas, Notosuchus terrestris, Comahuesuchus brachybuccalis, Cynodontosuchus rothi, Wargosuchus australis, Lomasuchus palpebrosus, Gasparinisuchus peirosauroides,Bayomesasuchus hernandezi, Patagosuchus anieliensis, and Barrosasuchus neuquenianus) were recovered from the province of Neuquén (Patagonia, Argentina). From the northern of the province, at the Rincón de los Sauces region the species Pehuenchesuchus enderi and Kinesuchus overoi were described. Field work carried on in recent years in the region provided numerous crocodyliforms remains such as teeth, cranial and postcranial (osteoderms, vertebrae and appendicular) elements. Here, we provide a revision of the crocodyliforms remains in light of new findings housed in the Museo Municipal Argentino Urquiza (MAU). Many of this fossil record is from the Cerro Overo-La Invernada, 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 the fossils are isolated and/or articulated fragments. Osteoderms are abundant with ornamentation based in subcircular pits, and a keel marked or not (e.g. MAU-Pv-LE-619, MAU-Pv-CO-692 to 695, 699 and 701). In second order 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 amphycelic vertebral body, both cervical, thoracic, lumbar, sacral and caudal (e.g. MAU-Pv-CO-584, 674). Appendicular elements include 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 were found (e.g. MAU-Pv-CO-632 and 686). Some mandibular fragments correspond to articular (as articular, surangular and 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 found as well (e.g. MAU-Pv-PH-437, MAU-Pv-LI-691). All the mentioned crocodyliforms remains are assigned to Peirosauridae, except MAU-Pv-N-280 that could belong to a derived notosuchian. This shows the dominance of the peirosaurids in the paleoenviroment of the region for the Upper Cretaceous (Coniacian to Santonian age mainly) in contrast with others notosuchians groups (such as notosuchids or baurusuchids).