Abstract

ZAVATTIERI, Ana María  and  ARCUCCI, Andrea B.. Age and stratigraphic position of the tetrapods from the cerro Bayo at Potrerillos locality (Triassic), Mendoza, Argentina. Ameghiniana [online]. 2007, vol.44, n.1, pp.133-142. ISSN 1851-8044.

The age of the Río Mendoza Formation at Potrerillos, Cuyana Basin, was previously assigned to the Lower Triassic on the basis of its tetrapod content. However, many authors considered this as controversial and at present the unit is assigned to the Middle Triassic because it rests unconformably upon the Choiyoi Group, whose uppermost levels are locally established for the early Middle Triassic. The tetrapod remains formerly recovered in this sequence came from a few meters below thick tuffaceous beds (pink, grey, green) from violet and reddish mudstones which are attributed herein as proceeding from the middle to upper part of the Cerro de Las Cabras Formation. New material of kannemeyeriid dicynodonts and indeterminate eucynodonts from the northern side of Cerro Bayo of Potrerillos come from the same stratigraphic levels of the Cerro de Las Cabras Formation, instead of the Río Mendoza Formation, as previously thought. Taking into account the microfloristic assemblage yielded by the Cerro de Las Cabras Formation, the age of the oldest amniotes recorded from the Cuyana Basin cannot be older than the late Middle Triassic.

Keywords : Tetrapods; Cerro de Las Cabras Formation; Triassic; Cuyana Basin.