This article is about the animal. For other uses, see Snake (disambiguation).
SnakesTemporal range: 145–0 Ma
Cretaceous – Recent
Coast garter snake,
Thamnophis elegans terrestris
Scientific classification [ e ]
* Alethinophidia – Nopcsa, 1923
*Scolecophidia – Cope, 1864
World range of snakes
(rough range of sea snakes in blue)
Snakes are elongate, legless, carnivorous reptiles of the suborder Serpentes that can be distinguished fromlegless lizards by their lack of eyelids and external ears. Like all squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales. Many species of snakes have skulls with many morejoints than their lizard ancestors, enabling them to swallow prey much larger than their heads with their highly mobile jaws. To accommodate their narrow bodies, snakes' paired organs (such askidneys) appear one in front of the other instead of side by side, and most have only one functional lung. Some species retain a pelvic girdle with a pair of vestigial claws on either side of the cloaca.Living snakes are found on every continent except Antarctica and on most islands. Fifteen families are currently recognized, comprising 456 genera and over 2,900 species. They range in size fromthe tiny, 10 cm-long thread snake to pythons and anacondas of up to 7.6 metres (25 ft) in length. The recently discovered fossil Titanoboa was 15 metres (49 ft) long. Snakes are thought to haveevolved from either burrowing or aquatic lizards during the Cretaceous period (c 150 Ma). The diversity of modern snakes appeared during the Paleocene period (c 66 to 56 Ma).
Most species are...