Features of osteology in stylopodium and zeugopodium of Didelphis marsupialis

Abstract

Comparative observations in the hind limb of the opossum, a primate predecessor, reveal essential differences regarding lower leg coupling mechanisms. Especially the primate ankle shows cardan joint properties, causing inversion of the foot before toe-off. Inversion is turning the footsole inwards, eversion is turning it outwards. By bony landmarks, features of longitudinal rotation of bones from 3-D frames were matched to available radiocinematographs of walking stages in (a) early stance, (b) mid-stance, (c) toe-off, and (d) swing.