Alligatoridae

Alligators and Caimans make up the second largest family of the crocodilians, Alligatoridae. There are 4 genera and about 7 known species of Alligatorids. Alligatorids range in size depending on species. The Chinese alligator (Aligator sinensis) is usually about  while the American Alligator (A. mississippiensis) is usually . The largest American alligator was  long. The Black Caiman of the Amazon can reach as much as .

Alligatorids live in the southern United States, Central America, northern South America and near the Yangzee river in China. 

Alligators vs crocodiles
There are several differences between alligators and crocodiles. Alligators have shorter and wider snouts. They prefer fresh water to saltwater. Crocodiles have a gland that removes much of the salt. Alligators do not have this gland. In alligators, the fourth tooth of their lower jaw fits into a pit in the upper jaw. In crocodilians this tooth fits into a groove on the outside of the jaw. Alligators are also less aggressive than crocodilids. Usually only the largest of the species are a threat to humans.

 Species 
 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 (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

category:Crocodilia