| Squamata Fossil range: Jurassic—Recent | |
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| Scientific classification
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Order |
Squamata
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Squamata, or the scaled reptiles, is the largest recent order of reptiles, including lizards and snakes. Members of the order are distinguished by their skins, which bear horny scales or shields. They also possess movable quadrate bones, making it possible to move the upper jaw relative to the braincase.
Classification[]
Classically, the order is divided into three suborders:
- Lacertilia, the lizards;
- Serpentes, the snakes;
- Amphisbaenia, the worm lizards.
Of these, the lizards form a paraphyletic group.
Evolution[]
Squamates are a monophyletic group that is a sister group to the tuatara. The squamates and tuatara together are a sister group to crocodiles and birds, the extanct archosaurs. Squamate fossils first appear in the early Jurassic, but a mitochondrial phylogeny suggests that they evolved in the late Permian. The evolutionary relationships within the squamates are not yet completely worked out, with the relationship of snakes to other groups being most problematic. From morphological data, Iguanid lizards have been thought to have diverged from other squamates very early, but recent molecular phylogenies, both from mitochondrial and nuclear DNA, do not support this early divergence[1]. Because snakes have a faster molecular clock than other squamates,[1] and there are few early snake and snake ancestor fossils,[2] it is difficult to resolve the relationship between snakes and other squamate groups.
References[]
- ^ a b Kumazawa, Yoshinori (2007). "Mitochondrial genomes from major lizard families suggest their phylogenetic relationships and ancient radiations". Gene 388: 19–26. doi:.
- ^ "Lizards & Snakes Alive!". American Museum of Natural History. http://www.amnh.org/exhibitions/lizards/snakes/world.php. Retrieved on 2007-12-25.
References[]
- Bebler, John L.; King, F. Wayne (1979). The Audubon Society Field Guide to Reptiles and Amphibians of North America. New York: Alfred A. Knopf. pp. 581. ISBN 0394508246.
- Capula, Massimo; Behler (1989). Simon & Schuster's Guide to Reptiles and Amphibians of the World. New York: Simon & Schuster. ISBN 0671690981.
- Cogger, Harold; Zweifel, Richard (1992). Reptiles & Amphibians. Sydney, Australia: Weldon Owen. ISBN 0831727861.
- Conant, Roger; Collins, Joseph (1991). A Field Guide to Reptiles and Amphibians Eastern/Central North America. Boston, Massachusetts: Houghton Mifflin Company. ISBN 0395583896.
- Ditmars, Raymond L (1933). Reptiles of the World: The Crocodilians, Lizards, Snakes, Turtles and Tortoises of the Eastern and Western Hemispheres. New York: Macmillian. pp. 321.
- Freiberg, Dr. Marcos; Walls, Jerry (1984). The World of Venomous Animals. New Jersey: TFH Publications. ISBN 0876665679.
- Gibbons, J. Whitfield; Gibbons, Whit (1983). Their Blood Runs Cold: Adventures With Reptiles and Amphibians. Alabama: University of Alabama Press. pp. 164. ISBN 978-0817301354.
- McDiarmid, RW; Campbell, JA; Touré, T (1999). Snake Species of the World: A Taxonomic and Geographic Reference. 1. Herpetologists' League. pp. 511. ISBN 1893777006.
- Mehrtens, John (1987). Living Snakes of the World in Color. New York: Sterling. ISBN 0806964618.
- Rosenfeld, Arthur (1989). Exotic Pets. New York: Simon & Schuster. pp. 293. ISBN 067147654.