Crocodilians

30 species

Crocodilians are mostly large, predatory, semiaquatic reptiles. They first appeared 95 million years ago in the Late Cretaceous period (Cenomanian stage) and are the closest living relatives of birds. This family includes the true crocodiles (family Crocodylidae), the alligators and caimans (family Alligatoridae), and the gharial and false gharial (family Gavialidae). Crocodilians swim well and can move on land in a \"high walk\" and a \"low walk\", while smaller species are even capable of galloping. Their skin is thick and covered in non-overlapping scales. They have conical, peg-like teeth and a powerful bite. They have a four-chambered heart and, somewhat like birds, a unidirectional looping system of airflow within the lungs, but like other living reptiles, they are ectotherms (“cold-blooded”). Crocodilians are found mainly in lowlands in the tropics, but alligators also live in the southeastern United States and the Yangtze River in China. They feed on animals such as fish, crustaceans, molluscs, birds, and mammals. Crocodilians are typically solitary and territorial, though cooperative feeding does occur. During breeding, dominant males try to monopolize available females. Females lay eggs in holes or in mounds and, unlike most other reptiles, care for their hatched young. Some species of crocodilians are known to have attacked humans, especially the Nile crocodile which has the largest number of attacks.
Crocodilians are mostly large, predatory, semiaquatic reptiles. They first appeared 95 million years ago in the Late Cretaceous period (Cenomanian stage) and are the closest living relatives of birds. This family includes the true crocodiles (family Crocodylidae), the alligators and caimans (family Alligatoridae), and the gharial and false gharial (family Gavialidae). Crocodilians swim well and can move on land in a \"high walk\" and a \"low walk\", while smaller species are even capable of galloping. Their skin is thick and covered in non-overlapping scales. They have conical, peg-like teeth and a powerful bite. They have a four-chambered heart and, somewhat like birds, a unidirectional looping system of airflow within the lungs, but like other living reptiles, they are ectotherms (“cold-blooded”). Crocodilians are found mainly in lowlands in the tropics, but alligators also live in the southeastern United States and the Yangtze River in China. They feed on animals such as fish, crustaceans, molluscs, birds, and mammals. Crocodilians are typically solitary and territorial, though cooperative feeding does occur. During breeding, dominant males try to monopolize available females. Females lay eggs in holes or in mounds and, unlike most other reptiles, care for their hatched young. Some species of crocodilians are known to have attacked humans, especially the Nile crocodile which has the largest number of attacks.