Marine Lizard Fossils Show Evolution of Snakes’ Mouths

Snakes can swallow prey whole because their jaws can separate, but the jaws of lizards, ancestors of the snakes, are firmly held together--leaving biologists to ponder how the mouth-stretching ability evolved. Now, researchers at the University of Queensland in Australia have discovered that mososaurs, large marine lizards that lived 60 million to 110 million years ago, displayed an intermediate stage of evolution.

The team reports in today’s Nature that newly discovered fossils show that mososaurs had a fixed upper jaw, but a flexible lower jaw that permitted a large mouth opening. They also had long gripping teeth at the back of the palate, like snakes, to help them hold prey.

Compiled by Times medical writer Thomas H. Maugh II