REVISITING THE UPPER CRETACEOUS NOASAURID RECORD OF THE NEUQUÉN BASIN, PATAGONIA, ARGENTINA

BAIANO, M.A.; CORIA, R.A.; WINDHOLZ, G.J.; MESO, J.G.

Puerto Madryn

Congreso; Reunión de comunicaciones de la Asociación Paleontológica Argentina (RCAPA, 2018).; 2018

Asociación Paleontológica Argentina

Noasauridae is a family of abelisauroid theropods that has a scarce record in South America, which, up to now, was only represented by small-sized forms from the Hauterivian (Lower Cretaceous) Ligabueino andesi Bonaparte; the Santonian(Upper Cretaceous) Velocisaurus unicus Bonaparte; and the Campanian Maastrichtian (Upper Cretaceous) Noasaurus leali Bonaparte and Powell. Here we report the recognition of noasaurid features in two medium-sized specimens, MCF-PVPH53 and 398, both consisting of proximal humeral ends. MCF-PVPH-53 was collected from the Coniacian?Turonian (Upper Cretaceous) levels of the Portezuelo Formation, which had been formerly assigned as an indeterminate abelisauroid that presents the noasaurid synapomorphy of a stout humeral head in proximal view, less than two times wider than long. In turn, MCF-PVPH-398, which comes from the Campanian Anacleto Formation, has a weakly developed greater tubercle positioned at the level of the internal tuberosity, resembling the condition present in the noasaurid Elaphrosaurus Janensch. Furthermore, the humeral head is inflated and the internal tuberosity is extremely reduced in both MCF-PVPH-53 and 398, as in noasaurids like Elaphrosaurus and Masiakasaurus Sampson, Carrano and Forster, but unlike the ball-like humeral headand the well-developed internal tuberosity observed in Abelisauridae. The presence of noasaurids in the Turonian?Campanian interval enriches the South American record of Noasauridae, and depicts the presence of medium-sized noasaurids in the Upper Cretaceous, which, up to now, was composed of small-sized forms such as Masiakasaurus, Noasaurus and Velocisaurus.