Gerrhosaurus major, the Sudan plated lizard, occurs in semi-arid areas of eastern and southern Africa, occasionally occupying burrows and termite mounds. This omnivorous species reaches a maximum snout-vent length of roughly 23 cm. Gerrhosaurus is a member of Scleroglossa (see also Varanus, Lanthanotus), one of the two major squamate clades (the other being Iguania, e.g., Ctenosaura, Phrynosoma). Within Scleroglossa, Gerrhosaurus resides in Gerrhosauridae (see also Gerrhosaurus nigrolineatus and Tracheloptychus petersi), the hypothesized sister taxon to Cordylidae.

Gerrhosauridae is diagnosed, in part, by the following (from Lang, 1991): nasal and prefrontal bones in broad contact; palatine and jugal bones in contact or overlap at the infraorbital foramen; postfrontal not forked medially; supratemporal fenestra entirely closed by postfrontal and squamosal; median posterior processes of parietal bone deeply forked bracing the supraoccipital ridge; skull darkly pigmented; and pterygoid teeth present.

The cranial osteoderms in this group (right side of skull, in red) have long hampered the study of their cranial bones. In the specimen featured here, some of the unfused osteoderms on the left side of the skull had been physically removed (see 'skeleton only' animations above). However, it is difficult to remove the osteoderms that actually coossify with the dorsal cranial bones without damaging the skull. CT data make it possible to digitally erase the osteoderms and render the skull without them (left side of skull); animations of the skull with the osteoderms digitally removed can be found under 'Additional Imagery'.

This specimen was collected in the Kilifi District of Kenya. It was made available to the University of Texas High-Resolution X-ray CT Facility for scanning by Mr. Jens Vindum of the California Academy of Sciences Department of Herpetology, and Dr. Chris Bell of The University of Texas at Austin.

The specimen was scanned by Cambria Denison, Timothy Rowe, and Richard Ketcham on 25 February 1998 along the coronal axis for a total of 330 slices, each slice 0.16 mm thick, with an interslice spacing of 0.15 mm (for a slice overlap of 0.01 mm).

Literature

Cordyliformes Bibliographie, containing over 1100 citations on cordylids and gerrhosaurids

Estes, R. 1983. Sauria terrestria, Amphisbaenia. Handbuch der Paläoherpetologie, Part 10A. Gustav Fischer Verlag, Stuttgart, 249 pp.

Estes, R., K. de Queiroz, and J. Gauthier. 1988. Phylogenetic relationships within Squamata; pp. 119-281 in R. Estes, and G. Pregill (eds.), Phylogenetic Relationships of the Lizard Families. Stanford University Press, Stanford, California.

Lang, M. 1991. Generic relationships within Coryliformes (Reptilia: Squamata). Bulletin de L'Institut Royal des Sciences Naturelles de Belgique Biologie 61:121-188.

Malan, M. E. 1941. Cranial anatomy of the genus Gerrhosaurus. South African Journal of Science 37:192-217.

Links

A care sheet for plated lizards

Three-dimensional volumetric renderings of skull with the osteoderms digitally removed. All are 2mb.

No osteoderm yaw movie	No osteoderm pitch movie	No oosteoderm roll movie