Sphenosuchus acutus

Early Jurassic of South Africa. Discovered in early 20th century, and described in 1915. Carnivorous and long-legged; presumably largely terrestrial.

It is uncertain over whether it was quadrupedal or a facultative biped. It was thoroughly described in 1972, and was an important specimen leading to the hypothesis about the common ancestry of birds and crocodiles. Sphenosuchians offer a window into how the true crocodile lineage of pseudosuchians began.

Terrestrisuchus
Artistic interpretation of Sphenosuchus by John Conway