The cranial anatomy of the hog-nosed snakes (Heterodon)

Abstract

The cranial osteology and myology of the Xenodontine snake genus Heterodon are described and correlated with certain aspects of the trunk musculature. Comparisons are made with the genus Xenodon and the viperidae. Heterodon, and to a lesser extent Xenodon, are similar to the Viperidae in many features of their cranial and trunk myology. A Xenodontine protoviper is hypothesized that gave rise to three present-day snake groups: (1) the advanced xenodontine snakes such as Xenodon, (2) the more primitive but specialized Heterodon, and (3) the vipers.