A new medium-sized abelisaurid (Theropoda, Dinosauria) from the late cretaceous (Maastrichtian) Allen Formation of Northern Patagonia, Argentina

Abelisaurid theropods are well known in Cretaceous beds along South America, particularly Patagonia. However, the record of latest abelisauroids is still far from satisfactory. Until recently, few taxa were described Maastrichtian beds: Carnotaurus sastrei and Quilmesaurus curriei, but also perhaps Abelisaurus comahuensis. In this contribution, we describe a new genus species (Niebla antiqua gen. et sp. nov.), medium-sized abelisaurid coming Late (Maastrichtian) Río Negro province, northern Patagonia, Argentina. The paleohistological analysis shows that individual has reached somatical maturity it represents an adult mid-sized abelisaurid. specimen represented by nearly complete braincase, fragmentary jaw teeth, relatively scapulocoracoid, dorsal ribs incomplete vertebrae. taxon small, much smaller than other coeval abelisaurids such as Abelisaurus. braincase autapomorphic features dorsoventrally tall basal tuber postemporal foramen enclosed parietal exoccipitals. scapulocoracoid notably similar to having posterodorsally oriented glenoid, expanded wide coraco-scapular plate, very narrow straight scapular blade. These different those abelisaurids, which may indicate unique conformation pectoral girdle among these American theropods.