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Permo-Triassic archosauromorph from Uruguay

Ben Creisler

A new online paper in open-access pre-print form:

Martin Ezcurra, Pablo Velozo, Melitta Meneghel & Graciela Piñeiro (2014)
Early archosauromorph remains from the Permo-Triassic Buena Vista
formation of NorthEastern Uruguay.
PeerJ PrePrints 2:e678v1
doi: http://dx.doi.org/10.7287/peerj.preprints.678v1

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.