The crocodilians

23 different species of crocodiles live on our planet. They are scattered in the tropical and subtropical regions, more precisely in America, Africa, Australia and Asia. These 23 species are part of 3 families:

-The crocodilidae which count 13 species.
-The alligatoridae which count 2 alligator species and 6 caiman species .
-The gavialidae which count 2 species.

They may be caimans, alligators, gavials or crocodiles, they all are crocodilians.
Yet some details allow us to differentiate them accurately:
-Among the crocodiles, the fourth tooth shows from the lower jaw when the mouth is shut. -Among the alligatoridae, no tooth shows from the lower jaw when the mouth is shut.
-As to the gavials, they have a very thin, long and cylindrical snout. Nevertheless other criteria allow us to differentiate them, such as internal anatomy or the study of extinct and fossilized specimens.

These classification studies have a name: the TAXONOMY. The first crocodilians appeared during the Secondary era, over 200 million years ago, but they have been existing under their present appearence for 65 million years. They outlived dinosaurs for a reason still unknown to scientists. They are oviparous and curiously enough their genetic analisys shows they are nearer to birds than lizards and snakes. The general anatomy of a crocodilian -Their size varies from 1.5 to 6 meters.

-They have a thick skin protected by scales (osteodermises) -Their jaws can close with a maximum pressure of 1,350 kg per cm2. -Their cone-shaped teeth are used to pierce and retain their preys.