The Scaly OnesAbstractThere are about 7, 200 species of snakes and lizards which evolved from the order of Squamata or “the scaly ones”. The group’s evolutionary history can be traced back to its split from a common lizard-like reptile ancestor with the Rhynchosephalia during the Lower or Middle Triassic periods.
After 30 to 60 million years, coinciding with the division of Pangaea, Squamata further divided into two groups, the Iguania and Scleroglossa. Iguanians exhibits most of the features found in its earlier Squamate ancestors such as rigid skulls, sedentary lifestyle and reliance on vision.On the other hand, scleroglossans developed flexible jaws, firmer tongues and vomeronasal organ embedded in the roof of their mouth. Of the two groups, scleroglossan is believed to be more successful, since they outnumber the iguanians in a 4.5 to 1 ratio, and they dominate the ground while iguanians are confined to restricted habitats.
At about 180 million years ago, the scleroglossans split into the gekkota, which are nocturnal and subterranean dwellers and the autarchoglossa, which are diurnal and continue to live in the grounds. The evolutionary changes and adaptation that happened in the order Squamata led to the diverse species of snakes and lizards that currently exists.