TAFONOMÍA DEL DINOSAURIO TERÓPODO ANIKSOSAURUS DARWINI, FORMACIÓN BAJO BARREAL, CRETÁCICO TARDÍO DE PATAGONIA (ARGENTINA)

Abstract

Aniksosaurus darwini is a coelurosaurian theropod from the Bajo Barreal Formation (Upper Cretaceous), south of Chubut province, Patagonia, Argentina. The fossils include postcranial remains of 5 individuals and they were preserved in a mantle overbank deposit associated to a fluvial system of low sinuosity. A detailed analysis on the biostratinomic, fossildiagenetic, and paleoenvironmental aspects of the site of occurrence of Aniksosaurus, allows us to recognize two meteorization stages and their pos- sible association with the origin of accumulation of the skeletons. Moreover, tooth marks in one of the femora, preliminary, are assigned to a small crocodyliform. The taphonomic study adds new anatomic evidences related to soft tissues. The holotype, MDT-Pv 1/48, is represented by an articulated right hindlimb, including, femur, tibia, metatarsals and phalanges. The subaerial weathering and abrasion due to transport on the femur strongly contrast with the preservation of the rest of the hindlimb bones, suggesting the presence of a protector soft tissue re- sembling the podoteca seen in extant birds. The presence of this soft tissue in Aniksosaurus, could support the early occurrence of this feature in basal coelurosaurians.