The hind limb ofMacrocnemus bassanii(Nopcsa) (Reptilia, Diapsida): development and functional anatomy

Abstract

Previously undescribed material of Macrocnemus bassanii (Reptilia, Diapsida, Prolacertiformes) adds considerable detail to the knowledge of the anatomy of the postcranial skeleton. The ontogeny of the tarsus and the homologies of its constituent elements are discussed. The reptilian calcaneum corresponds to the amphibian fibulare, while the reptilian astragalus incorporates the amphibian intermedium together with additional ossification centers; the presence of a tibiale in reptiles is controversial. The tarsus of Macrocnemus incorporates the astragalus (intermedium), calcaneum (fibulare), a centrale, and the distal tarsals 4, 3, and 1. A functional analysis of the appendicular skeleton suggests predominantly terrestrial habits, perhaps even facultative bipedalism during rapid locomotion.