NEW ELASMARIAN ORNITHOPOD REMAINS FROM CERRO OVERO-LA INVERNADA (BAJO DE LA CARPA FORMATION, SANTONIAN), NORTHERN PATAGONIA, ARGENTINA

GONZÁLEZ-DIONIS, J.; PENÉLOPE CRUZADO-CABALLERO; FILIPPI, LEONARDO S.; PAULINA-CARABAJAL, ARIANA; BARRIOS, F.; GIANECHINI FEDERICO A.; SECULI-PEREYRA, E.E.; GARCÍA, S.L.; ULLOA-GUAIQUIN, K.S. ; BELLARDINI, F. ; BALARINO, M.L. ; GARRIDO, ALBERTO C.; ARIEL H. MÉNDEZ

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Congreso; XXXV Jornadas Argentinas de Paleontología de Vertebrados; 2022

The ornithischian fossil record of Argentina has increased in recent years, with the ornithopod cladeexhibiting the greatest paleodiversity. The outcrops of Bajo de la Carpa Formation (Santonian, Upper Cretaceous) at the Cerro Overo-La Invernada area (Rincón de los Sauces, Neuquén province) are a hotspot for ornithopod remains. From this area, the articulated remains of Mahuidacursor lipanglef (MAU-Pv-CO-596), and several indeterminate ornithopod postcranial elements have been found. In recent years, our multidisciplinary team has carried out numerous field expeditions in the area, collecting among other remains the postcranial materials presented in this contribution. The new postcranial bones consisting of a dorsal vertebral centrum (MAU-Pv-CO-683), a proximal fragment of a pubis (MAU-Pv-CO-681), a proximal and a distal end of a right femur (MAU-Pv-CO-684), and a proximal and a distal end of a metatarsal II (MAU-Pv-CO-682). These elements show the following set of morphological features that allow us to refer them to Ornithopoda, and preliminary to elasmarians indet.: a) the spool-shape of the dorsal vertebral centrum, which are amphiplatyan and longer anteroposteriorly than dorsoventrally; b) a subcircular anterior articular surface of the dorsal vertebral centrum; c) a subquadrangular transverse section of the femur; d) a greater trochanter located at the same level than the femoral head and has a sigmoidal lateral margin in proximal view; e) a pendant fourth trochanter located on the proximal half of the femur; and f) metatarsal II laterally compressed in proximal view. The dorsal vertebra (MAU-Pv-CO-683) shows unfused neurocentral sutures and numerous nutritional foramina in lateral, medial, and ventral views. In addition, the pubis has a closed obturator foramen, probably related to its ontogenetic state. The new remains increase the record and improve our knowledge about the paleobiogeography of elasmarian ornithopods during the Santonian in northern Patagonia.