CAUDATA

also called Urodela, one of the major extant orders of the class Amphibia. It includes salamanders and newts. The relatively small and inconspicuous salamanders are important members of north temperate and some tropical ecosystems, in which they are locally abundant and play important roles. They are important as subjects of experimental studies in embryology, developmental biology, physiology, anatomy, biochemistry, genetics, and behaviour. Convenient size, low food requirements, low metabolic rate, and hardiness make them useful laboratory animals. Additional reading The fossil record of salamanders is thoroughly reviewed by Richard Estes, Gymnophiona, Caudata, vol. 2 in Oskar Kuhn (ed.), Encyclopedia of Paleoherpetology (1981). Relationships of salamanders to other amphibians are analyzed in two articles in Herpetological Monographs: A.R. Milner, The Paleozoic Relatives of Lissamphibians, 6:826 (1993); and D.C. Cannatella and D.M. Hillis, Amphibian Relationships: Phylogenetic Analysis of Morphology and Molecules, 6:17 (1993).Phylogenetic relationships of the families of salamanders are the subject of several recent investigations, and a consensus is gradually growing. A general review of this controversial topic is found in A. Larson and W.W. Dimmick, Phylogenetic Relationships of the Salamander Families: An Analysis of Congruence Among Morphological and Molecular Characters, Herpetological Monographs, 6:7793 (1993). Treatments of specific taxa based mainly on morphological traits include the following: on Ambystomatidae, H.B. Shaffer, Phylogenetics of Model Organisms: The Laboratory Axolotl, Ambystoma mexicanum, Systematic Biology, 42(4):508522 (1993); on Plethodontidae, Allan Larson, Neontological Inferences of Evolutionary Pattern and Process in the Salamander Family Plethodontidae, Evolutionary Biology, 17:119217 (1984); David B. Wake, Comparative Osteology and Evolution of the Lungless Salamanders, Family Plethodontidae (1966); and Symposium on the Biology of Plethodontid Salamanders, Herpetologica, 49(2):153237 (1993); on Rhyacotritonidae, David A. Good and David B. Wake, Geographic Variation and Speciation in the Torrent Salamanders of the Genus Rhyacotriton (Caudata: Rhyacotritonidae) (1992); and on Salamandridae, Reiner Klewen, Die Landsalamander Europas (1988 ); Robert Thorn, Les Salamandres d'Europe, d'Asie et d'Afrique du Nord (1968); and David B. Wake and N. zeti, Evolutionary Relationships in the Family Salamandridae, Copeia, 1969:124137 (1969).The neuroethology of feeding is treated in depth by Gerhard Roth, Visual Behavior in Salamanders (1987). The great range in genome and cell sizes and its developmental and evolutionary implications is treated by Stanley K. Sessions and Allan Larson, Developmental Correlates of Genome Size in Plethodontid Salamanders and Their Implications for Genome Evolution, Evolution, 41(6):12391251 (November 1987). Variation in cloacal structure and its phylogenetic implications are studied by D.M. Sever, Comparative Anatomy and Phylogeny of the Cloacae of Salamanders (Amphibia: Caudata). I. Evolution at the Family Level, Herpetologica, 47(2):165193 (1991).The biology of the tropical species is summarized by David B. Wake, Adaptive Radiation of Salamanders in Middle American Cloud Forests, Annals of the Missouri Botanical Garden, 74(2):242264 (1987). The large salamander fauna of China are studied by Ermi Zhao (Erh-Mi Zhao) et al., Studies on Chinese Salamanders (1988). Patterns of evolution found in salamanders are treated by David B. Wake and Allan Larson, Multidimensional Analysis of an Evolving Lineage, Science, 238(4823):4248 (Oct. 2, 1987). David B. Wake