Boas

Most sandboas are relatively small snakes, less than 3 ft (1 m) in length, currently found in southern Asia and northern Africa, and in western North America. In most ways the sandboas are very much like the true boas of South America, but because most of them live in relatively treeless areas, they are more adapted to burrowing in the sand than to climbing. Like the South American boas, they feed on small animals, such as lizards and rodents, which they kill by constriction. Because of their subterranean habits, however, the sandboas tends to have small, compact heads that can be pushed through the soil, and short, stubby tails that can act as "pushers." Their tail vertebrae are specialized and can be recognized in the fossil members of this family. Such sandboa fossils are known from many localities in western Europe and eastern North America that are very distant from the areas sandboas currently inhabit. The two American sandboas are the rubber boa of the dry pine forests of the western states of Washington and Oregon, and the rosy boa of the southwestern desert regions. The latter is a handsome snake that is a favorite of pet owners.

As in the true boas, there is a strange situation in sandboa distribution and relationship. On the island of Madagascar, off the southeast coast of Africa, there are two boas that resemble those of South America. One of these is specialized as a tree boa, the other is so similar in appearance to the South American boa constrictor that some experts have placed it in the same genus. Recent research, however, suggests that despite their superficial similarities the Madagascan boas are related to the sandboas, and probably represent an ancient division of that group.