大象传媒

Considering that some snakes jump to get around and some sidewind, having no legs would not seem to be much of a handicap. But how did snakes get this way? One hundred million years ago, in the time of the dinosaurs, their remote ancestors did have legs, rather like today's lizards. Some were probably very good runners, but others started to burrow in search of prey. However, legs are a hindrance below ground so over generations their legs would have become smaller. Today, burrowing lizards such as skinks seem to be going through the same process. Many have tiny, but recognisable, legs while others have functionless flaps. And some lizards have lost their legs completely, so they have the body of a snake but the face of a lizard.