Classification: Reptiles
Reptiles
Reptiles are air-breathing, cold-
blooded vertebrates that have
skin covered in scales as op-
posed to hair or feathers. They
are tetrapods (having or having
descended from vertebrates with
four limbs) and amniotes, whose
embryos are surrounded by an
amniotic membrane. Modern rep-
tiles inhabit every continent with
the exception of Antarctica, and
are represented by four living or-
ders:
* Crocodilia (crocodiles, gavials, caimans and alligators): 23 species
* Sphenodontia (tuatara from New Zealand): 2 species
* Squamata (lizards, snakes and amphisbaenids ("worm-lizards"): ap-
proximately 7,900 species
* Testudines (turtles, tortoises and terrapins): approximately 300 spe-
cies
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 ovovivi-
parity (egg retention), or viviparity
(offspring born without use of cal-
cified eggs). Many of the vivipa-
rous 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 the newly-discovered Jaragua Sphaero,
at 1.6 cm (0.6 in), to the Saltwater Crocodile, at up to at least 7 m (23 ft).
Reptiles!
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