The snake group, Serpentes, is placed with
lizards in the major reptile group Squamata.
The fossil history of snakes is far shorter
than that for lizards, stretching back to' the .
Late Cretaceous Period about 80 million
years ago. The group origins are obscure:
two suggestions include evolution from
some type of burrowing lizard, hence the
loss of limbs; or evolution from a form of
aquatic lizard. The snake skull is usually
low and squat, with a flattened forehead
and loose ja:w articulation (joint). This .
allows a very wide gape and 'dislocation'
of the jaws to permit swallowing large prey
whole, since the teeth are slim and fang-like
and cannot bite off lumps or chew.