Paleontological record of the Laguna Colorada Formation (El Tranquilo Group), Late Triassic of Patagonia Argentina

ADRIANA MANCUSO; ROGER SMITH; DIEGO POL; CERDA, IGNACIO; ALEJANDRO OTERO; CLAUDIA MARSICANO

Ciudad Autónoma de Buenos Aires

Jornada; 26 Jornadas Argentinas de Paleontología de Vertebrados; 2012

Universidad Maimónides

Recent fieldwork at the Laguna Colorada Formation provided new material and more information about the paleontological content of the unit. The material previously described includes adults and post-hatchling individuals (associated with eggs) referred to Mussaurus patagonicus (basal sauropodomorphs) and remains of a heterodontosaurid ornithischian. We present here an assemblage of at least fourteen juvenile specimens of Mussaurus patagonicus that includes partially or fully articulated, similarly-sized young individuals. Some of the skeletons retain a life-like crouched position with flexed limbs, whereas others have articulated limbs that penetrate up to 13cm into the underlying strata. This bonebed was found in the same levels in which previous materials were recorded. The newly collected materials were found under different taphonomic conditions, from articulated to completely disarticulated skeletons, but all remains derived from the same bed. The Laguna Colorada Formation consists of reddish to brownish siltstones and claystones, fine to medium sandstones and subordinate thin conglomerates deposited by moderate sinuosity fluvial system. The dinosaur remains preserved in the unit provided from a massive package of grayish red mudstone that were deposited in a floodplain as loess deposits.