The reptilian brain is similar to that of amphibians, except the cerebrum and cerebellum are
slightly larger. Most typical sense organs are well developed with certain exceptions most
notably the snakes lack of external ears (middle and inner ears are present). All reptilians
have advanced visual depth perception compared to other animals.
Lizards and Snakes
Lizards and snakes belong to the largest recent order of reptiles (Squamata). Members of
the order are distinguished by their skin, which bears horny scales or shields. They also
possess movable quadrate bones, making it possible to move the upper jaw relative to the
braincase. This is particularly visible in snakes, which are able to open their mouths very
widely to accommodate comparatively large prey (Figure13.21).
Figure 13.21: A corn snake swallowing a mouse. ( 20 )Lizards are a large and widespread group of reptiles, with nearly 5,000 species, ranging
across all continents except Antarctica. Most lizards have four limbs, external ears, movable
eyelids, a short neck, a long tail, and are insectivores. Many can shed their tails in order to
escape from predators.
Vision, includingcolorvision, isparticularlywelldevelopedinlizards, andmostcommunicate
with body language, bright colors, orpheromones.Adults range from a few cm ( 1 in) in
length (some Caribbean geckos) to nearly 3 m (10 ft) (Figure13.22), although most species
are less than 220 g (0.5 lb).
Encompassing40families, thereistremendousvarietyincolor, appearanceandsizeoflizards.
Most lizards are oviparous, although a few species are viviparous. Many are also capable
of regeneration of lost limbs or tails. Almost all lizards are carnivorous, although most are
so small that insects are their primary prey. A few species are omnivorous or herbivorous,