Riojasuchus tenuisceps

Late Triassic of Argentina (<230Ma). Discovered in 1967. A member of the ornithosuchids (“bird crocodiles”), a small group of poorly understood pseudosuchians that were once thought to be ancestors to tyrannosaurs or other dinosaurs, but now understood to be distant cousins of crocodiles. Riojasuchus is relatively well known from four partial skeletons preserved in 3D. Ornithosuchus is another member of this group, from Scotland; mainly preserved as natural moulds in sedimentary rock.

Armoured, carnivorous, with an unusual “hooked” (downturned) snout, and unique in having a “crocodile-reversed” ankle joint (calcaneum bone’s projection inserts into a socket in the astragalus; opposite other pseudosuchians). Some features of the hindlimbs convergently evolved with dinosaurs and have caused prior studies to suggest complete or “facultative” bipedalism, which this project will be testing.


Life reconstruction of Riojasuchus tenuisceps by Jorge Gonzalez.
From Baczko, M. B. von, J. B. Desojo, and D. Ponce. 2020. Postcranial anatomy and osteoderm histology of Riojasuchus tenuisceps and a phylogenetic update on Ornithosuchidae (Archosauria, Pseudosuchia). Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2019.1693396.