Isolated archosauriform teeth from the upper triassic candelária sequence (Hyperodapedon Assemblage Zone, Southern Brazil)

Abstract

We describe isolated teeth found in the locality “Sítio Piveta” (Hyperodapedon Assemblage Zone, Candelaria Sequence, Upper Triassic of the Paraná Basin). The material consists of five specimens, here classified into three different morphotypes. The morphotype I is characterized by pronounced elongation, rounded base and symmetry between lingual and labial surfaces. The morphotype II presents serrated mesial and distal edges, mesial denticles decreasing in size toward the base, distal denticles present until the base and asymmetry, with a flat lingual side and rounded labial side. The morphotype III, although similar to morphotype II, has a greater inclination of the posterior carinae. The conservative dental morphology in Archosauriformes makes difficult an accurate taxonomic assignment based only on isolated teeth. However, the specimens we present are attributable to “Rauisuchia” (morphotype II and III) and, possibly, Phytosauria (morphotype I). The putative presence of a phytosaur in the Carnian Hyperodapedon Assemblage Zone would have impact in the South American distribution of the group. The taxonomic assignments proposed herein contribute to the faunal composition of the Hyperodapedon Assemblage Zone, a critical unit on the study of the Upper Triassic radiation of archosaurs.