The cranial development of Elaphe obsoleta (Ophidia, colubridae).

The kinetic skull of snakes is a highly specialized structure that has allowed these limbless organisms to exploit a wide variety of habitats. Here we analyze the development of the cranium in the colubrid snake Elaphe obsoleta quadrivittata based on two sets of embryos raised under controlled conditions and preserved at regular intervals during embryogenesis. Emphasis is on the interactions between dermal and endochondral ossification in the basicranium and in the posterior orbitotemporal region. In Elaphe, the laterosphenoid initially develops as an ascending process of the basal plate and is a combination of membrane and cartilage bone. The maxilla shows a peculiar pattern of differentiation from several centers of ossification.