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Lizard is the common name used for all squamate reptiles other than snakes (and to a lesser extent amphisbaenians), encompassing over 7,000 species, [1] ranging across all continents except Antarctica, as well as most oceanic island chains.
Squamata (/ s k w æ ˈ m eɪ t ə /, Latin squamatus, 'scaly, having scales') is the largest order of reptiles, comprising lizards and snakes.With over 12,162 species, [3] it is also the second-largest order of extant (living) vertebrates, after the perciform fish.
This is a checklist of American reptiles found in Northern America, based primarily on publications by the Society for the Study of Amphibians and Reptiles (SSAR). [1] [2] [3] It includes all species of Bermuda, Canada, Greenland, Saint Pierre and Miquelon, and the United States including recently introduced species such as chameleons, the Nile monitor, and the Burmese python.
The major reptile group Diapsida, for example, is defined by the presence of two temporal fenestrae on each side of the skull. The infratemporal fenestra , also called the lateral temporal fenestra or lower temporal fenestra , is the lower of the two and is exposed primarily in lateral (side) view.
The gastralia may have been involved in the breathing process in early amphibians and reptiles. The pelvis and shoulder girdles are arranged differently from those of lizards, as is the case with other parts of the internal anatomy and its scales. [70]
However, it is represented by only one living species: the tuatara (Sphenodon punctatus), a superficially lizard-like reptile native to New Zealand. [ 5 ] [ 6 ] Lepidosauria is a monophyletic group (i.e. a clade ), containing all descendants of the last common ancestor of squamates and rhynchocephalians. [ 7 ]
The earliest forms, like Placodus, which lived in the early to middle Triassic, resembled barrel-bodied lizards superficially similar to the marine iguana of today, but larger. In contrast to the marine iguana, which feeds on algae , the placodonts ate molluscs and so their teeth were flat and tough to crush shells.
Scutes on a crocodile. Reptile skin is covered with scutes or scales which, along with many other characteristics, distinguish reptiles from animals of other classes. They are made of alpha and beta-keratin and are formed from the epidermis (contrary to fish, in which the scales are formed from the dermis).