Gerrhonotus liocephalusTexas Alligator Lizard

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Geographic Range

Though uncommonly seen in its most suitable habitats, Gerrhonotus liocephalus has a range from the Edwards Plateau of Central Texas, south throughout low-mid elevations in eastern Mexico.

Habitat

The Texas Alligator Lizard can be found on rocky hillsides and slopes, wooded canyons, and near rocky streams and springs.

Physical Description

Gerrhonotine lizards are known for their broad heads, short limbs and being heavily armored with scales, from which the common name alligator lizard derived. Gerrhonotus liocephalus, in particular, can be easily recognized by 16 longitudinal rows of dorsal scales and 46 to 54 dorsal scales from the occiput to the base of the tail (Brown 1950). Osteologically, it has supranasal expansion, prefrontal-superciliary contact, a single preocular, loss of one canthal/loreal element, and two temporals contacting the orbit (Good 1988). The color pattern of this species undergoes considerable change with age. Hatchlings are a deep metallic brown with well-defined white crossbands (Bartlett 1999). Adult color pattern ranges from a tan yellowish to a reddish brown with eight to ten lighter crossbands on the dorsum that are weakly edged with brown. The head and ventrum are unmarked with the tail being similar to the dorsum. Crossbands on aged specimens are vague. Texas Alligator Lizard hatchlings are around four inches in length, and can reach up to 20 inches in length at full maturiy (Bevans 1956).

Reproduction

Breeding and reproduction of the oviparous Gerrhonotine lizards occur throughout the year (Bockstanz 1999). In a breeding position, the head of the female is held diagonally in the jaws of the male during the many hours required to complete the process (Smith 1946). For egg deposition, females prefer a ground area that holds a small amount of moisture. This moist ground usually tends to be under a fallen trunk or flat rock. Most clutches produced are eight to twenty eggs, and the females brood their eggs through the fifty to seventy days of incubation (Bartlett 1999).

Behavior

Texas Alligator Lizards are looked upon as an oddity by residents even in areas where they are common, which suggests secretive habits. The species shows no trace of social behavior, but some fighting may occur between competitive breeding males. This diurnal lizard's climbing and concealment abilities make up for its lack of sprinting power (Bevans 1956). However, if it happens to be in a hurry, the alligator lizard can quickly progress by folding its legs against the body and moving in a serpentine motion (Bartlett 1999). If grabbed by the tail by one of its predators, the tail will be detached and used as a writhing decoy, allowing the lizard to escape. Some of its predators may include snakes (racers, rattlesnakes, garter snakes), the red-tailed hawk, and domestic cats (Smith 1946).

Food Habits

The Texas Alligator Lizard is carnivorous, feeding on insects (beetles, caterpillars, grasshoppers), snails, scorpions, and spiders (Bockstanz 1999). Bird eggs are an occassional meal.

Conservation Status

Contributors

Glenda Holland (author), Michigan State University, James Harding (editor), Michigan State University.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

chaparral

Found in coastal areas between 30 and 40 degrees latitude, in areas with a Mediterranean climate. Vegetation is dominated by stands of dense, spiny shrubs with tough (hard or waxy) evergreen leaves. May be maintained by periodic fire. In South America it includes the scrub ecotone between forest and paramo.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

the area in which the animal is naturally found, the region in which it is endemic.

References

Bartlett, R. 1999. A Field Guide to Texas Reptiles and Amphibians. Houston, Texas: Gulf Publishing Company.

Bevans, M. 1956. The Book of Reptiles and Amphibians. Garden City: Garden City Books.

Bockstanz, L. January 14, 1999. "Herps of Texas" (On-line). Accessed November 16, 1999 at http://www.zo.utexas.edu/research/txherps/lizards/.

Brown, B. 1950. An Annotated Check List of the Reptiles and Amphibians of Texas. Waco: Baylor University Press.

Good, D. 1988. Phylogenetic Relationships Among Gerrhonotine Lizards. Los Angeles: University of California Press.

Smith, H. 1946. Handbook of Lizards. Ithaca: Comstock Publishing Company.

Uetz, P. November 10, 1995. "The EMBL Reptile Database" (On-line). Accessed November 10, 1999 at http://www.embl-heidelberg.de/~uetz/LivingReptiles.html.