FRIDAY, Feb. 27, 2004 (HealthDayNews) -- Snakes lived on the land, not in the ocean, when they evolved into limbless creatures from their lizard ancestors about 150 million years ago.
So claims a Penn State University study that will appear in the May 7 issue of Biology Letters.
The study, the first to analyze genes from all the living families of lizards, may resolve a long-standing debate about whether snakes evolved in a terrestrial or marine setting. The researchers came to their conclusion after studying two genes from 64 species representing all 19 families of living lizards and 17 species of the 25 families of living snakes.
"We felt it was important to analyze genes from all the lizard groups because almost every lizard family has been suggested as being the one most closely related to snakes. If we had failed to include genes from even one of the lizard families, we could have missed getting the right answer," researcher S. Blair Hedges, a biology professor at Penn State, says in a prepared statement.
The gene analysis revealed snakes are most closely related to current lizards who are descendents of ancient land-based lizards.
He says the finding suggests a reason why they lost their limbs, which would be that they interfered with burrowing into the ground.
"Having limbs is a real problem if you need to fit through small openings underground, as anybody who has tried exploring in caves knows. Your body could fit through much smaller openings if you did not have the wide shoulders and pelvis that support your limbs," Hedges says.
The Center for Reptile and Amphibian Conservation and Management has more on snakes.