INVESTIGADORES
EZCURRA Martin Daniel
artículos
Título:
Redescription and phylogenetic relationships of the proterochampsid Rhadinosuchus gracilis (Diapsida: Archosauriformes) from the early Late Triassic of southern Brazil
Autor/es:
EZCURRA, M. D.; DESOJO, J. B.; RAUHUT, O. W. M.
Revista:
AMEGHINIANA
Editorial:
ASOCIACION PALEONTOLOGICA ARGENTINA
Referencias:
Lugar: Buenos Aires; Año: 2015
ISSN:
0002-7014
Resumen:
The proterochampsids are small to medium-sized,
quadrupedal and probable semi-aquatic reptiles that were part of the evolutionary
radiation of Archosauromorpha during the Triassic. The group is restricted to
the Middle and Late Triassic of South America with eight nominal species. Rhadinosuchus gracilis Huene was the
first described proterochampsid and comes from the late Carnian?earliest Norian
of southern Brazil. This genus and species is currently the most enigmatic and
poorly known member of the group and, as a result, we redescribe here its anatomy
and discuss its phylogenetic relationships. We found that this species can be
distinguished from other proterochampsids and we dismiss the proposed synonym
with Cerritosaurus binsfeldi Price. Our
quantitative phylogenetic analysis found Rhadinosuchus
gracilis as more closely related to Gualosuchus
reigi Romer and Chanaresuchus
bonapartei Romer than to other
proterochampsids, together forming the subfamily Rhadinosuchinae. Characters
supporting this assignment include a maxilla with a distinct longitudinal
change in slope between lateral and dorsal surfaces, and dorsal surface of nasal and frontal ornamented
by ridges disposed in a radial pattern. In addition, Rhadinosuchus gracilis was found as the sister taxon of Chanaresuchus bonapartei based on a
lacrimal with an antorbital fossa that occupies almost half or more of the
anteroposterior length of the ventral process. The topology of the phylogenetic
analysis shows that the Brazilian species do not form a monophyletic clade and favours
multiple dispersal events between the Ischigualasto-Villa Unión (northwestern
Argentina) and the Paraná (southern Brazil) basins.