Reptiles, or members of the class Reptilia, are air-breathing, generally "cold-blooded" (poikilothermic) amniotes that generally have skin covered in scales or scutes. They are tetrapods (having or having descended from vertebrates with four limbs) and lay amniote eggs, whose embryos are surrounded by the amnion membrane. Modern reptiles inhabit every continent with the exception of Antarctica, and four living orders are currently recognized:
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Reptiles, or members of the class Reptilia, are air-breathing, generally "cold-blooded" (poikilothermic) amniotes that generally have skin covered in scales or scutes. They are tetrapods (having or having descended from vertebrates with four limbs) and lay amniote eggs, whose embryos are surrounded by the amnion membrane. Modern reptiles inhabit every continent with the exception of Antarctica, and four living orders are currently recognized:
The majority of reptile species are oviparous (egg-laying) although certain species of squamates are capable of giving live birth. This is achieved, either through ovoviviparity (egg retention), or viviparity (offspring born without use of calcified eggs). Many of the viviparous species feed their fetuses through various forms of placenta analogous to those of mammals with some providing initial care for their hatchlings. Extant reptiles range in size from a tiny gecko, Sphaerodactylus ariasae, that grows to only 1.6 cm (0.6 in), to the saltwater...
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