the Linton, Ohio Anthracodromeus: World’s First Facultative Biped?

Abstract

The history of vertebrate bipedialism, once thought to have begun with the Mid-Permian Eudibamis cursoris (Berman, et al. 2000) may have started even earlier in the Upper Carboniferous. Evidence suggests the Westphalian reptile Anthracodromeus longipes, found rarely and exclusively at the Linton lagerstatte in south eastern Ohio, may have possessed facultative bipedal capabilities. Anthracodromeus was originally described by Edward Drinker Cope in 1874 as an amphibian and later correctly diagnosed as reptile by Donald Baird in 1958. Only two partial skeletons and a few disarticulated remains, all without a complete skull, are currently known. This study recognizes the potential adaptations for facultative bipedialism as shown in the second, recently recovered partial skeleton which is well articulated showing limb element lengths, foot morphology, spine proportions and pelvic details allowing us to predict the animal's ability to run on two limbs in a manner similar to modern lizards including the widely known Basiliscus plumifrons of South America.