MUSEO ARGENTINO DE CIENCIAS NATURALES "BERNARDINO RIVADAVIA"
Unidad Ejecutora - UE
Reappraisal of the Taxonomic status of Aetosauroides (Archosauria: Aetosauria) specimens from the Late Triassic of South America and their proposed synonymy with Stagonolepis.
DESOJO, J.B.; EZCURRA, M.
JOURNAL OF VERTEBRATE PALEONTOLOGY
SOC VERTEBRATE PALEONTOLOGY
Año: 2011 vol. 31 p. 596 - 596
The SouthAmerican record of early Late Triassic aetosaurs is composed of two species: Aetosauroides scagliaiand Aetosauroides subsulcatus. Previously undescribed materials belonging to Aetosauroides subsulcatus allow us to reassessits taxonomy, leading us to consider it a junior synonym of Aetosauroides scagliai. Based on the emended diagnosis ofthe species provided here, we recognize that specimens assignable to Aetosauroides scagliai are less common than thoughtpreviously and several of them are not diagnostic beyond indeterminate non-typothorasicine aetosaurins. Previous assignmentsof Aetosauroides as a junior synonym of Stagonolepis are not followed because the South American taxon is distinctdue to the presence of a maxilla excluded from the external narial margin, tooth crowns with a straight distal margin andwithout a constriction between the root and crown, a gradually convex ventral margin of the dentary, oval fossae ventral tothe neurocentral suture on the lateral sides of the centra, and a ratio between the length and the width between the distal-mosttips of the postzygapophyses equal to or lower than 0.75. The evidence provided here bolsters the validity of Aetosauroidesand extends the distribution of Aetosauroides scagliai into southern Brazil. Although Stagonolepis was employed as an indextaxon for the Adamanian LVF, this genus is currently restricted to Europe and North America. Thus, no overlapping generaor species of aetosaur are shared between South America and other landmasses. Accordingly, the record of aetosaurs is notuseful for providing biostratigraphical correlations between Late Triassic South American beds and those in other regions.