Suborder: Lacertilia—Lizards
[CLICK
FOR KEY TO LIZARD INFRAORDERS]
Definition: Lizards
are reptiles in which the skull is diapsid but lacks a lower arch of
bone (leaving the quadrate moveable), and the lower halves of the jaw
are firmly fixed in the front (excepting some pygopod species).
Lizards can be distinguished from snakes in that lizards have at least
one of the following characteristics that snakes never possess: an
external ear opening, moveable eyelids, or legs. Legless lizards never
have long, forked snake-like tongues.
Lizards are an old group of
vertebrates, with fossils dating back to the early Jurassic Period.
Fossils of intact (or nearly intact) lizards have been taken in amber,
but these are only a few million years old. Shown here is a gecko
(genus Sphaerodactylus, the smallest of the geckos) preserved
in amber.
