LIZARD

any member of the suborder Sauria, a group of vertebrates that with snakes (suborder Serpentes) make up some 95 percent of living reptiles. They are scaly-skinned reptiles, closely allied to snakes but usually distinguished by the possession of legs, movable eyelids, and external ear openings. Most of the 3,000 living species of lizards inhabit warm regions of the Earth, but some are found nearly to the Arctic Circle in Eurasia and others to the southern tip of South America. The lizards are usually considered part of the reptilian order Squamata. The worm lizards, or amphisbaenians, which are included in this article for convenience of comparison with lizards, are placed in their own suborder, Amphisbaenia, by many modern taxonomists. suborder name Sauria, any of about 3,700 species of vertebrates that together with the snakes (suborder Serpentes) make up 95 percent of living reptiles. Although most diverse and abundant in the tropics, they are also found from the Arctic Circle to southern Africa, South America, and Australia. Lizards share with snakes the presence of ectodermal scales, paired male copulatory organs (hemipenes), and flexible skulls. Typical lizards have moderately cylindrical bodies, four well-developed legs, a tail slightly longer than the head and body, and movable lower eyelids. They range in size from 3 to more than 300 centimetres (1 inch to 10 feet), but most are about 30 cm (12 in.) long. Ornamentation includes crests on the head, back, or tail, spines, brightly coloured throat fans, and throat frills. Like fish and amphibians, lizards are cold-blooded animals; i.e., the temperature of the environment regulates their body temperature, although a few species have the ability to store the Sun's warmth for extended periods of time. Most lizards lay eggs, which they bury in the ground; in the embryo, a special tooth is formed for rupturing the shell. A number of species, however, bear live young. Members of most species feed on insects and rodents, but some, such as the iguana, are herbivorous. Additional reading General surveys of the species of lizards and their life histories, with many photographs, are found in K.P. Schmidt and R.F. Inger, Living Reptiles of the World (1957, reissued 1967); A.F. Carr, The Reptiles, rev. ed. (1980); R. Mertens, The World of Amphibians and Reptiles (1960; originally published in French, 1959); and H.M. Smith, Handbook of Lizards: Lizards of the United States and of Canada (1946, reissued 1979). V.A. Harris, The Anatomy of the Rainbow Lizard (1963), provides a dissection manual for students, moderately technical but very readable. Of a more technical nature is a work by A.S. Romer: Osteology of the Reptiles (1956). W.W. Milstead (ed.), Lizard Ecology; A Symposium (1967), contains summaries of research in population ecology, physiological ecology, and social behaviour, with panel discussions of the reports; an excellent source for understanding trends in research.Important taxonomic books and papers, not easily read by the layperson but fundamental to an understanding of the classification, are: C.L. Camp, Classification of the Lizards, Bull. Am. Mus. Nat. Hist., 48:289480 (1923); R. Hoffstetter, Revue des rcentes acquisitions concernant l'histoire et la systmatique des squamates, in Problms actuels de palontologie (volutions des vertbrs), pp. 243279 (1962); A.G. Kluge, Higher Taxonomic Categories of Gekkonid Lizards, and Their Evolution, Bull. Am. Mus. Nat. Hist., 135:159 (1967); S.B. McDowell and C.M. Bogert, The Systematic Position of Lanthanotus and the Affinities of the Anguinomorphan Lizards, ibid., 105:1142 (1954); M.R. Miller, The Cochlear Duct of Lizards, Proc. Calif. Acad. Sci., 4th series, 33:255359 (1966), and The Cochlear Duct of Snakes, ibid., 35:425476 (1968); G. Underwood, On the Classification and Evolution of Geckoes, Proc. Zool. Soc., Lond., 124:469492 (1954), On Lizards of the Family Pygopodidae, a Contribution to the Morphology and Phylogeny of the Squamata, J. Morph., 100:207268 (1957), and A Contribution to the Classification of Snakes, Publs. Br. Mus. Nat. Hist., no. 635 (1967); A.E. Greer, A Subfamilial Classification of Scincid Lizards, Bull. Mus. Comp. Zool. Harv., 139:151183 (1970).