Appearance and identification: Adult American Alligators are between 6-16.5 feet (1.8-2.5 meters). The largest alligator recorded was 19 feet 2 inches (Conant, 1998) although today an adult male of 13 feet (4 meters) is considered large. Juveniles are black with narrow yellow crossbands and are about 8.5-9 inches at hatching. As they grow larger, the crossbands fade, although the yellow crossbands may persist (but not conspicuously). Adults are generally black in color. American Alligators can be distinguished from American crocodiles (crocodylus acutus) by their broadly rounded snout and the absence of the characteristic protruding 4th tooth of crocodiles (subfamily crocodylinae). A resident of river swamps, lakes, marshes, and other bodies of water along the Atlantic coastal plain (see range maps and biogeography below), the alligator can often be seen basking or floating in the water in "wilder" areas.
Range map from Thermoregulation of the American Alligator in the Everglades
|Found exclusively in the southeastern United States along the Atlantic coastal plains from Texas east to South Carolina and south to Florida.|
Taxonomic history derived from Crocodilian, Tuatara, and Turtle Species of the World ed. by F. Wayne King and Russell L. Burke (see complete citation below and in bibliography). An online version of this material is also available. click here
Alligator Cuvier 1807, Annales du Museum d'Histoire Naturelle Paris 10:25
Type species: Crocodilus mississipiensis Daudin 1801 
Comment: First designated Crocodilus lucius Cuvier 1807, the type species of Crocodilus mississipiensis Daudin 1801 , Histoire Naturelle, Generale et Particuliere des Reptiles 2:412.
Mertens 1956 in Hemming, Bulletin of Zoological Nomenclature 12(6):175, designated the holotype specimen used by Daudin as the lectotype (see note below) of Crocodilus lucius described by Cuvier 1807, making these species synonyms. The International Commission on Zoological Nomenclature then ruled that Crocodilus mississipiensis Daudin 1801  was the type species of the genus Alligator Cuvier 1807 (reported by Hemming 1958 in Opinions and Declarations Rendered by the International Commission on Zoological Nomenclature 1 (F.8):87-126).
Alligator mississippiensis (Daudin 1801 )
Original name: Crocodilus mississipiensis
Type: Holotype: Museum National d'Histoire Naturelle (as reported by Guibe in a personal reply in Hemming 1956, Bulletin of Zoological Nomenclature 12:173)
Type Locality: "les bords du Mississipi," USA
Comment: Holbrook 1842, North American Herpetology 2:53 emended Daudin's mississipiensis to "mississippiensis" on the basis that the name refers to the Mississippi River. This emendation was declared valid by the International Commission on Zoological Nomenclature (reported by Hemming 1958 in Opinions and Declarations Rendered by the International Comm. on Zool. Nomen. 1F(F.8):87-126.
Cuvier, G.L.C.F.D. 1807. Sur les differentes especes de crocodiles vivans et sur leurs caracteres distinctifs. Annales du Museum d'Histoire Naturell. Paris. 10:8-66, pls. 1-2.
Daudin, F.M. 1801 . Histoire Naturelle, Generale et Particuliere des Reptiles; ouvrage faisant suit a l'Histoire naturelle generale et particuliere, composee par Leclerc de Buffon; et redigee par C.S. Sonnini, membre de plusiers societes savantes. F. Dufart Paris. 2:1-432, pls. 27-28.
Hemming, F. 1956. Proposed use of the plenary powers to ensure that the specific name "mississipiensis" Daudin, [1801-1802] as published in the combination "Crocodilus mississipiensis" shall be the oldest available name for the North American alligatos (Class REptilia) (Supplement to, and, in part, correction of, a ruling given in "Opinion" 92). Bulletin of Zoological Nomenclature. London. 12(6):163-175.
Hemming, F. 1958. I.C.Z.N. Direction 97 (name and spelling of Alligator mississipiensis). Opinions and Declarations Rendered by the International Commission on Zoological Nomenclature 1F(F.8):87-126.
King, F.W. and Burke, R.L. (eds.) Crocodilian, Tuatara, and Turtle Species of the World: a taxonomic and geographic reference. Washington DC: Association of Systematics Collections, 1989.
King, F. Wayne, and Russell L. Burke (eds.). 1997. Crocodilian, Tuatara, and Turtle Species of the World: An Online Taxonomic and Geographic Reference [Online]. Association of Systematics Collections, Washington, D.C. 294 p. Available: http://www.flmnh.ufl.edu/natsci/herpetology/turtcroclist/ [7 April 1997].