Early archosauromorph remains from the Permo-Triassic Buena Vista Formation of north-eastern Uruguay

PeerJ. 2015 Feb 19:3:e776. doi: 10.7717/peerj.776. eCollection 2015.

Abstract

The Permo-Triassic archosauromorph record is crucial to understand the impact of the Permo-Triassic mass extinction on the early evolution of the group and its subsequent dominance in Mesozoic terrestrial ecosystems. However, the Permo-Triassic archosauromorph record is still very poor in most continents and hampers the identification of global macroevolutionary patterns. Here we describe cranial and postcranial bones from the Permo-Triassic Buena Vista Formation of northeastern Uruguay that contribute to increase the meagre early archosauromorph record from South America. A basioccipital fused to both partial exoccipitals and three cervical vertebrae are assigned to Archosauromorpha based on apomorphies or a unique combination of characters. The archosauromorph remains of the Buena Vista Formation probably represent a multi-taxonomic assemblage composed of non-archosauriform archosauromorphs and a 'proterosuchid-grade' animal. This assemblage does not contribute in the discussion of a Late Permian or Early Triassic age for the Buena Vista Formation, but reinforces the broad palaeobiogeographic distribution of 'proterosuchid grade' diapsids in Permo-Triassic beds worldwide.

Keywords: Archosauromorpha; Diapsida; Extinction; Palaeobiogeography; Permian; Proterosuchidae; South America.

Grants and funding

The research of MDE was funded by Emmy Noether Programme Award from the Deutsche Forschungsgemeinschaft (BU 2587/3-1 to Richard Butler) and by a Marie Curie Career Integration Grant (PCIG14-GA-2013-630123 to Richard Butler). ANII_FCE2011_6450 supported the research of GP, MM and PV. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.