The foundational characteristic is the "advanced mesotarsal" ankles, which are characterized by a large astragalus and a small calcaneum. This ankle orientation operated on a single hinge, allowing for better mobi… See more

Bird-line archosaurs appear in the fossil record by the Anisian stage of the Middle Triassic about 245 million years ago, represented by the dinosauriform Asilisaurus. However, Early Triassic fossil footprints reported in … See more

In 1986, Jacques Gauthier defined the name Ornithosuchia (previously coined by Huene) for a branch-based clade including all archosaurs more closely related to birds than to crocodiles. In the same year, Gauthier al… See more

• Michael J. Benton (2004). "Origin and relationships of Dinosauria". In David B. Weishampel; Peter Dodson; Halszka Osmólska (Hrsg.) (eds.). The Dinosauria. Berkeley: Zweite Auflage, University of California P… See more