Comparative anatomy of the intertarsal joint in extant and fossil birds: Inferences for the locomotion of Hesperornis regalis (Hesperornithiformes) and Emeus crassus (Dinornithiformes)
Reconstruction of the soft tissues (i.e., collateral ligaments, Lig. anticum, menisci, tendon of the M. fibularis brevis) involved in the mechanism of intertarsal joint stabilization in two species of extinct birds, Hesperornis regalis and Emeus crassus, allowed insights into their locomotion. The foot-propelled diving of Hesperornis included loon-like movement of the tarsometatarsus and grebe-like movement of the toes. Movement of the tarsometatarsus in Emeus was restricted to the parasagittal plane, thus resembling those of other Ratites and most highly cursorial birds.