Hind limb osteology of Gracilisuchus stipanicicorum (Archosauria: Pseudosuchia)

A detailed osteological analysis of the hind limb and pelvic girdle of Gracilisuchus stipanicicorum, a Triassic pseudosuchian archosaur from Argentina, reveals new insights into its anatomical features and evolutionary relationships. The study describes previously underdescribed or misinterpreted regions, providing a more comprehensive understanding of this extinct taxon. While Gracilisuchus shares morphological traits with non-crocodyliform crocodylomorphs—such as the poorly developed femoral fourth trochanter and an underdeveloped femoral head—it lacks key features (e.g., an imperforated acetabulum) that would place it within Crocodylomorpha. These findings tentatively support its affiliation with Sphenosuchia, a clade of early crocodylomorphs, positioning Gracilisuchus as a sister taxon to this group rather than a direct ancestor.

Lecuona, A., & Desojo, J. B. (2012). Hind limb osteology of Gracilisuchus stipanicicorum (Archosauria: Pseudosuchia). Earth and Environmental Science Transactions of the Royal Society of Edinburgh, 102(2), 105–128. https://doi.org/10.1017/s1755691011000181