Reptile

The reptiles are a group of vertebrate animals, today represented with four orders:

                                    Kingdom: Animalia
   * Order Testudines (turtles):
     300 species                    Phylum:  Chordata
   * Order Rhynchocephalia          Class:   Reptilia
     (tuataras from New Zealand):
     2 species                                       Orders
   * Order Squamata (lizards and    Order Crocodilia (Crocodilians)
     snakes): 7,600 species         Order Rhynchocephalia (Tuataras)
   * Order Crocodilia               Order Squamata
     (crocodilians: crocodiles and    Suborder Sauria (Lizards)
     alligators): 23 species          Suborder Serpentes (Snakes)
                                    Order Testudines (Turtles and their kin)
Reptiles include all the amniotes
except birds and mammals. Traditionally, they were grouped together in the
class Reptilia, as biologists had observed common features among them.
However, in recent years biologists have tendended to emphasize that groups
should be monophyletic, i.e. include all descendants of a particular form.
Since birds originated from a particular group of reptiles, members of that
group (including Crocodilia) are closer related to them than to other
reptiles. Similarly certain extinct forms are closer to mammals than to any
extant reptiles. As such, the Reptilia are a paraphyletic group.

Newer systems abandon or alter the composition of the Reptilia. The
synapsids, comprising mammals and their close relatives, are typically
excluded. If the other amniotes are all closer related to each other than to
the synapsids, as is currently expected, than they form a monophyletic
group, which is called the Reptilia or Sauropsida. However, it should be
noted that this group includes birds.

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