The Crurotarsi (also Crocodylotarsi Benton and Clark, 1988) are a group of archosaurs that includes the crocodiles (Crocodylia) and some extinct taxa such as the Phytosauria .
features
The common ancestral feature ( synapomorphism ) is the typical formation of the ankle joint , with the joint line running between the two proximal (“upper”) tarsal bones astragalus and calcaneus . Opposite the Crurotarsi are the Ornithodira ( pterosaurs and dinosaurs ) as a sister group , in which the ankle joint runs between the proximal and distal ("lower") tarsal bones.
Archosaurs' hocks with a schematic course of the joint line
Typical crurotarsal ankle
Ankle joint of the ornithodires (derived mesotarsal joint) for comparison