Ornithosuchids

Ornithosuchids were a group of extinct archosaurian reptiles that lived during the Late Triassic period. They are characterized by their unusual anatomy, which combined features found in both dinosaurs and crocodilians. Ornithosuchids possessed a combination of bipedal locomotion, indicated by their hindlimb structure, and a more sprawling gait that suggests they may have been capable of quadrupedal movement as well. Their skulls were heavily built, and they likely possessed powerful jaws, although their exact diet remains a subject of speculation.

The most distinctive feature of ornithosuchids is their pelvic girdle, which shows a mosaic of traits. The ilium, the upper part of the pelvis, was similar to that of early dinosaurs, while the ischium, the lower rear part, resembled that of crocodilians. This unusual arrangement has led to considerable debate among paleontologists regarding their precise evolutionary relationships. For a long time, they were considered close relatives of dinosaurs, but more recent analyses suggest they might represent an early offshoot of the archosaur lineage, closer to the divergence point of dinosaurs and crocodilians.

Fossils of ornithosuchids have been found in various locations, including South America and Europe. Notable genera include Ornithosuchus, Gracilisuchus, and Strigosuchus. These animals were medium-sized predators and are important for understanding the diversification of archosaurs during the Triassic. Their unique blend of anatomical features makes them a significant group for studying the evolution of the major archosaur clades that would come to dominate terrestrial ecosystems in the following Jurassic and Cretaceous periods.