Early archosauromorph remains from the Permo-Triassic Buena Vista Formation of north-eastern Uruguay.
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.
School of Geography, Earth and Environmental Sciences, University of Birmingham , Edgbaston, Birmingham , UK.
Martín D
MD
Ezcurra
Departamento de Evolución de Cuencas, Facultad de Ciencias , Iguá, Montevideo , Uruguay.
Pablo
P
Velozo
Laboratorio de Sistemática e Historia Natural de Vertebrados, Facultad de Ciencias , Iguá, Montevideo , Uruguay.
Melitta
M
Meneghel
Departamento de Evolución de Cuencas, Facultad de Ciencias , Iguá, Montevideo , Uruguay.
Graciela
G
Piñeiro
Archosauromorpha; Diapsida; Extinction; Palaeobiogeography; Permian; Proterosuchidae; South America