Ancestor of snakes, lizards likely gave birth to live young

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Posted on December 17, 2013
Ancestor of snakes, lizards likely gave birth to live young
Alex Pyron is the Robert F. Griggs Assistant Professor of Biology in the Columbian College of Arts and Sciences at the George Washington University. Credit: The George Washington University
The ancestor of snakes and lizards likely gave birth to live young, rather than laid eggs, and over time species have switched back and forth in their preferred reproductive mode, according to research published in print in Ecology Letters Dec. 17.

“This is a very unusual and controversial finding, and a major overturn of an accepted school of thought,” said Alex Pyron, Robert F. Griggs Assistant Professor of Biology in the Columbian College of Arts and Sciences at the George Washington University. “Before, researchers long assumed that the ancestor of snakes and lizards laid eggs, and that if a species switched to live birth, it never reverted back. We found this wasn’t the case.”

The findings push researchers’ understanding of the evolution of live birth a lot further back in time to 175 million years ago, showing that live birth has a much more ancient past as a strategy than previously believed. The findings are backed by several recent plesiosaur and mosasaur fossil discoveries and the fossil record of a few lizards from the Cretaceous Period, which had embryos in the mother and had live birth.

Read more at: Phys.org



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