Show Details

Snake v. Lizard

July 5, 2007

A listener asks: Which came first, the lizard or the snake?


Which came first: the lizard or the snake? I’m Bob Hirshon and this is Science Update.

There’s no doubt that snakes and lizards have a lot in common, so Brian of Gainesville, Florida, emailed to ask which came first. We turned to paleontologist Jerry Harris of Dixie State College in Utah.

JERRY HARRIS (Dixie State College):
Lizards evolved first.

He says the first lizard fossils are from 220 million years ago. Another million years after that, one type of lizard started losing its legs and became the snake. He says all the early snake fossils have been found in ancient oceans…

JERRY HARRIS (Dixie State College):
…So it looks like snakes evolved from swimming lizards—only later did snakes come back up onto land. Some of the most primitive living snakes—things like boas and pythons—also still have tiny remnants of hind legs and are good swimmers, just like their early ancestors.

If you have a science question, call us at 1-800-why-isit. If we use it on the air, you’ll win a Science Update mug. I’m Bob Hirshon, for AAAS, the science society.