As a crown group, Alligatoridae only includes the last common ancestor of all extant (living) alligators, caimans, and their descendants (living or extinct), whereas Alligatoroidea, as a stem-based group, also includes more basal extinct alligator ancestors that are more closely related to living alligators than to crocodiles or gavialids.

An alligator, or colloquially gator, is a large reptile in the genus Alligator of the family Alligatoridae in the order Crocodilia. The two extant species are the American alligator ( A. mississippiensis ) and the Chinese alligator ( A. sinensis ).

Alligatoroidea is one of three superfamilies of crocodylians, the other two being Crocodyloidea and Gavialoidea. Alligatoroidea evolved in the Late Cretaceous period, and consists of the alligators and caimans, as well as extinct members more closely related to the alligators than the two other groups.

In the family Alligatoridae, most caimans are confined to the tropical areas of Central and South America, though the ranges of the broad-snouted caiman (Caiman latirostris) and Jacaré caiman (C. yacare) extend into temperate areas of South America.

Alligatoridae is a family of large, semi-aquatic reptiles in the order Crocodilia, variously known by the common names of alligator and caiman, and characterized by a lizard-like appearance, armor-like skin, long tapering jaws, and the fourth enlarged tooth of the under jaw received into an internal pit formed for it within the upper jaw.

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

Like other members of the order, the family Alligatoridae are the descendants of the Archosauria, or "ruling lizards," which included the dinosaurs. A defining characteristic of these animals is a diapsid skull, which has two temporal openings.

Alligators and caimans are freshwater species that prefer still or slow-moving water, even if it is muddy or murky. Besides lakes, rivers, and streams, they are often found in swamps, marshes, and roadside ditches.

Alligatoridae. This family comprises alligators and caimans. There are four genera containing eight species. The top jaw overlaps the bottom so that, when the mouth is closed, only the upper teeth are visible. Pits are visible within the bony palate that receive the lower teeth when the jaw is closed (Fig. 8.2). In the upper jaw, the fourth ...

alligator, Either of two species of long-snouted reptiles constituting the genus Alligator (family Alligatoridae, order Crocodilia). Alligators differ from crocodiles in snout shape and tooth placement. Living in large bodies of water such as lakes, swamps, and rivers, these lizardlike carnivores use their powerful tail for defense and swimming.