Fossil snake sheds light on snake origins

Jeff Poling

The discovery of a new fossil snake may shed light on the poorly known evolution and ancestry of snakes, paleontologists announced April 16, 1997.

The scientists stated that the 97 ma old lizard fossil, discovered in Israel, may be one of the earliest snakes ever found. They also stated that the fossil provided "surprising and compelling" evidence that the nearest relatives to snakes were mosasaurs. Mosasaurs were giant marine lizards that became extinct at the end of the Cretaceous, and are thought to be closely related to modern varanid lizards such as the Komodo Dragon.

The fossil, named Pachyrhachis problematicus, was examined by Michael Caldwell of the Field Museum in Chicago and Michael Lee of the University of Sydney. The specimen was originally identified as a lizard, but Caldwell and Lee decided it looked more like a snake that still had tiny hind legs.

Some modern boa snakes still have vestigial legs, and other anatomical features of the fossil indicated it was a snake and not a lizard. The scientists stated that "Pachyrhachis has a small, narrow, lightly-built skull showing most [of the] derived features of modern snakes."

The scientists also believe certain anatomical characteristics show strong resemblances to those of marine mosasaurids, which they said could be, among lizards, the "nearest relatives of snakes."