Variation in the cranial osteology of the amphisbaenian genus Zygaspis based on high‐resolution x‐ray computed tomography

Abstract

AbstractAmphisbaenians are a specialized fossorial group of reptiles, having developed head‐first burrowing, a specialized skull architecture, and an elongated body. This group is generally small‐bodied, with some species possessing skulls only a few millimeters long. In this study, we used high‐resolution x‐ray computed tomography to compare the skulls of 15 specimens from seven of the eight species in the amphisbaenian genus Zygaspis (Zygaspis dolichomenta, Zygaspis ferox, Zygaspis quadrifrons, Zygaspis kafuensis, Zygaspis nigra, Zygaspis vandami, and Zygaspis violacea). Both interspecific and intraspecific variation, including asymmetry, is observed among the cranial bones of the specimens. There are unique morphological features on some cranial bones, including the premaxilla and ectopterygoid of Z. quadrifrons, the pterygoid and vomer of Z. kafuensis, and the extracolumella of Z. nigra. Sexual dimorphism has been previously reported for the species Z. quadrifrons and is observed here as well.