Non-archosaurian archosauromorphs from Argentina

EZCURRA, M. D.; DESOJO, J. B.

Contribuciones Científicas del Museo Argentino de Ciencias Naturales ?Bernardino Rivadavia?

Museo Argentino de Ciencias Naturales

Lugar: Capital Federal; Año: 2016 vol. 6 p. 49 - 56

Archosauromorpha includes all the diapsids closer to archosaurs than to lepidosaurs. Non-archosaurian archosauromorphs are restricted to the Triassic and were outstandingly morphologically diverse. The oldest known Argentinean non-archosaurian archosauromorphs are limited to fragmentary specimens from the Lower−Middle Triassic Tarjados Formation, but the latest Middle and Late Triassic record is considerably richer, being represented by rhynchosaurs, a ?proterosuchian-grade? archosauriform (Cuyosuchus), proterochampsids, and dowelliids. Rhynchosaurs were relatively poorly numerically abundant during the uppermost Ladinian of northwestern Argentina, but they became the dominant taxon of their tetrapod assemblage during the late Carnian−earliest Norian. Proterochampsids are endemic from the Upper Triassic of South America and their palaeobiogeographical distribution may have been limited by climatic barriers. Cuyosuchus is a relictual non-eucrocopodan archosauriform form the early Late Triassic of Mendoza. South American doswelliids are restricted to Argentinean and Brazilian beds deposited close to the Ladinian-Carnian boundary and distinctly differ morphologically from those of the Northern Hemisphere.