Alligatoridae

Taxobox
name = Alligators and Caimans
fossil_range = Cretaceous - Recent

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image_caption = American Alligator
regnum = Animalia
phylum = Chordata
classis = Sauropsida
ordo = Crocodilia
familia = Alligatoridae
familia_authority = Gray, 1844
subdivision_ranks = Living Genera
subdivision = "Alligator"
"Caiman"
"Melanosuchus"
"Paleosuchus"

Alligators and caimans are archosaurs, species of crocodilians and form the family Alligatoridae (sometimes regarded instead as the subfamily Alligatorinae).

Differences from crocodiles

Alligators differ from crocodiles principally in having wider and shorter heads, with more obtuse snouts; in having the fourth, enlarged tooth of the under jaw received, not into an external notch, but into a pit formed for it within the upper one; in lacking a jagged fringe which appears on the hind legs and feet of the crocodile; in having the toes of the hind feet webbed not more than half way to the tips; and an intolerance to salinity, alligators strongly preferring fresh water, while crocodiles can tolerate salt water due to specialized glands for filtering out salt. In general, crocodiles tend to be more dangerous to humans than alligators.

True alligators

Alligators proper occur in the fluvial deposits of the age of the Upper Chalk in Europe, where they did not die out until the Pliocene age. The true alligators are now restricted to two species, "A. mississippiensis" in the

Caimans

In Central and South America, the alligator family is represented by five species of the genus "Caiman", which differs from the alligator by the absence of a bony septum between the nostrils, and the ventral armour is composed of overlapping bony scutes, each of which is formed of two parts united by a suture. Some authorities further divide this genus into three, splitting off the smooth-fronted caimans into a genus "Paleosuchus" and the Black Caiman into "Melanosuchus". Caimans tend to be more agile and crocodile-like in their movements, and have longer, sharper teeth than alligators.cite book | author = Guggisberg, C.A.W. |url = | title = Crocodiles: Their Natural History, Folklore, and Conservation| year = 1972 | pages = pp.195 | id = ISBN 0715352725]

"C. crocodilus", the Spectacled Caiman, has the widest distribution, from southern Mexico to the northern half of Argentina, and grows to a modest size of about 2.2 meters. The largest is the near-threatened "Melanosuchus niger", the Jacare-assu, Large, or Black Caiman of the Amazon. Black Caimans grow to 16.5 feet (5 meters) [] , with the largest recorded size 5.79 m (19 ft). The Black Caiman and American Alligator are the only members of the alligator family posing the same danger to humans as the larger species of the crocodile family.

Although the Caiman has not been studied in-depth, it has been discovered that their mating cycles (previously thought to be spontaneous or year-round) are linked to the rainfall cycles and the river levels in order to increase their offspring's chances of survival.

pecies

* ORDER Crocodilia
** Family Alligatoridae
*** Genus "Leidyosuchus" (extinct)
*** Genus "Deinosuchus" (extinct)
*** Subfamily Alligatorinae
**** Genus "Albertochampsa" (extinct)
**** Genus "Chrysochampsa" (extinct)
**** Genus "Hassiacosuchus" (extinct)
**** Genus "Navahosuchus" (extinct)
**** Genus "Ceratosuchus" (extinct)
**** Genus "Allognathosuchus" (extinct)
**** Genus "Hispanochampsa" (extinct)
**** Genus "Arambourgia" (extinct)
**** Genus "Procaimanoidea" (extinct)
**** Genus "Wannaganosuchus" (extinct)
**** Genus "Alligator"
***** "Alligator prenasalis" (extinct)
***** "Alligator mcgrewi" (extinct)
***** "Alligator olseni" (extinct)
***** Chinese Alligator, "Alligator sinensis "
***** "Alligator mefferdi" (extinct)
***** American Alligator, "Alligator mississippiensis
*** Subfamily Caimaninae
**** Genus "Necrosuchus" (extinct)
**** Genus "Eocaiman" (extinct)
**** Genus "Paleosuchus"
***** Cuvier's Dwarf Caiman, "Paleosuchus palpebrosus"
***** Smooth-fronted Caiman, "Paleosuchus trigonatus"
**** Genus "Purussaurus" (extinct)
**** Genus "Mourasuchus" (extinct)
**** Genus "Orthogenysuchus" (extinct)
**** Genus "Caiman"
***** Yacare Caiman, "Caiman yacare"
***** Spectacled Caiman, "Caiman crocodilus "
****** "Rio Apaporis Caiman", "C. c. apaporiensis "
****** "Brown Caiman", "C. c. fuscus"
***** "Caiman lutescans" (extinct)
***** "Caiman sorontans"Fact|date=July 2008 (extinct) - Not reported in the literature, probably a 'nomen nudum'
***** Broad-snouted Caiman, "Caiman latirostris "
**** Genus "Melanosuchus"
***** "Melanosuchus fisheri" (extinct)
***** Black Caiman, "Melanosuchus niger"

References