Originally created 02/17/99

New study rethinks turtles' evolution



Turtles, it turns out, may not be the most ancient type of egg-laying animal alive today, according to a controversial new analysis.

Based on physical characteristics, scientists had long thought that turtles evolved before lizards, snakes, birds and crocodiles and alligators. But the new analysis, based on the largest available collection of reptile genes, contradicts that.

"Turtles turned out to be not where they were supposed to be on the family tree whenever their genes were included in a research study," said S. Blair Hedges of Pennsylvania State University, who led the new analysis published in the Feb. 12 issue of Science.

Turtles and crocodiles apparently shared a common ancestor some 200 million years ago, according to the analysis, making turtles, not birds, the closest relatives to crocodiles and alligators.