Stenoscelida

The holotype specimen, CAPPA/UFSM 0293, was found at the Exaeretodon sub-Assemblage Zone (Hyperodapedon Assemblage Zone) of the Santa Maria Supersequence (lower Candelaria Sequence) in the Paraná Basin. This locality is dated to the late Carnian/early Norian ages of the upper Triassic period, around 228 million years old. It consists of a complete, articulated right hind limb.

In 2022, Stenoscelida aurantiacus was described as a new genus and species of proterochampsid archosauriforms by Rodrigo T. Müller, Mauricio S. Garcia, and André O. Fonseca based on these remains. The generic name, "Stenoscelida ", is derived from the Greek words "στενός", meaning "narrow", and "σκέλος" meaning "hind leg", in reference to the morphology of the holotype remains. The specific name, "aurantiacus", means "orange" in Latin, in reference to the color of the sediments of the type locality.

Based on the known fossil remains, Stenoscelida would have been smaller than the related Pseudochampsa and Proterochampsa from Argentina.

In their phylogenetic analyses, Müller, Garcia & Fonseca (2022) recovered Stenoscelida as a member of the Proterochampsidae clade within Proterochampsia, in a polytomy with Tropidosuchus, Cerritosaurus, Gualosuchus, and Proterochampsa spp. In an updated analysis, Müller (2025) recovered greater resolution within Proterochampsia. He recovered Stenosclida immediately outside of the Proterochampsidae, as the sister taxon to this clade. These results are displayed in the cladogram below: