TAXONOMY
The order Squamata (squama is Latin for “scale”) comprises 95% of reptiles species and is divided into three suborders. In fact, 51% of known reptiles belong to just three squamate families: the colubrid snakes (23%), skinks (15%) and geckos
Reptiles
(13%) (Uetz 2000).
The Amphisbaenia (worm lizards) are less well known as they are underground burrowing lizards and are outside the scope of this book. The remaining suborders are the more familiar Serpentes (snakes) and Sauria/ Lacertilia (lizards). Lizards and snakes have extremely flexible| Table 4.1 Morphological differences between lizards and snakes | ||
| Sauria (lizards) | Serpentes (snakes) | |
| Limbs | Absent, two, four | Absent (vestigial) |
| Tongue | Short | Elongate |
| Eyelids | Present in most species | Absent |
| External ear | Present | Absent |
| Trunk | Short | Long |
| Tail | Long | Short |
| Mandibular symphysis | Present | Absent |
| Ventral scales | Several rows | Single scales (Gastropeges) |
| Table 4.2 Common Saurian infraorders and families | ||
| Infraorder | Family | Common species |
| Iguania | Iguanidae Agamidae Chamaeleonidae | Iguana, Anole, Chuckwallas, Basilisk Agamas, Water & Bearded dragons Chameleons |
| Gekkota | Gekkonidae | Geckos |
| Scincomorpha | Teiidae Scincidae | Tegus, Ameivas Skinks |
| Varanoidea | Helodermatidae Varanidae | Beaded lizards, Gila monster Monitors, Goanna, Komodo dragon |
skulls, known as kinetic skulls, whereas worm lizards have a heavily ossified skull which acts like a battering ram while burrowing.
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Worm lizards are mainly limbless, subterranean lizards and can move forward and backward with ease underground (amphisbaenia means “one who goes in both ways” in Greek).
Their eardrums and eyes are covered with opaque skin. Unlike lizards, they have very short tails and their skulls are heavily ossified to facilitate digging (Pough 2002).
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