The oldest noasaurid (Theropoda, Ceratosauria) from South America

CANALE, JUAN IGNACIO; GALLINA, PABLO ARIEL; APESTEGUÍA, SEBASTIÁN; HALUZA, ALEJANDRO

Corrientes

Jornada; XXXII Jornadas Argentinas de Paleontología de Vertebrados; 2018

Noasauridae is a group of poorly-known, small-sized theropod dinosaurs, wich show a wide geographical distribution (Gondwana and China) during a temporal range from Middle Jurassic to Upper Cretaceous times. Classically, this group included derived, Upper Cretaceous forms, but the recent inclusion of Elaphrosaurinae ceratosaurs, pushed the origins of the clade toward the Jurassic. Therefore, a temporal gap in the knowledge of this group occupies most of the Cretaceous. Here we report a new specimen of theropod from the Berriasian-Valanginian Bajada Colorada Formation (Neuquén Province, Argentina), including an axis (MMCh-Pv 67), a mid-posterior cervical vertebra (MMCh-Pv 199), a partial sacral centrum (MMCh-Pv 233), five caudal centra (MMCh-Pv 76, 77, 195, 225, 235) and a partial left femur (MMCh-Pv 234). The combination of long epipophysis on the axis, low and anteroposteriorly short cervical neural spine, and mediodistal crest of femur developed as a long flange allows referring this specimen to Ceratosauria. Its inclusion in two different published datasets focused on Ceratosaurian phylogeny recovered the specimen as part of the Noasauridae, closer to Late Cretaceous forms after the cervicals with long centra, narrow pre- and postspinal fossa in cervical vertebrae and cervical postzigapophyses overhanging the centrum posteriorly. The available evidence shows that noasaurid theropods were present in South America at least from the beginning of the Cretaceous.*Proyecto subsidiado por National Geographic Society (⧣W465-16) y Municipalidad de Villa El Chocón