A FOSSIL snake with well-developed rear limbs has fired the debate over whether snakes' ancestors lived on land or in the sea.
The 95-million-year-old Haasiophis terrasanctus was found in marine deposits north of Jerusalem. In 1996, researchers who studied a similar legged snake called Pachyrhachis decided that it was an ancestral snake that had never lost its rear legs. As Pachyrhachis was a sea predator, they concluded that itand all snakeshad evolved from marine lizards called mosasaurs (New Scientist, 30 November 1996, p 17).
But Olivier Rieppel of the Field Museum in Chicago thinks they got it wrong. He says Haasiophis could dislocate its jaw to swallow large preya feature that first appeared in advanced "big-mouth" snakes such as pythons. This suggests that far from being ancestral, both Haasiophis and Pachyrhachis are advanced snakes that had re-evolved legs. Snakes such as pythons retain limb buds, says Rieppel, so re-evolving ...
To continue reading this article, subscribe to receive access to all of newscientist.com, including 20 years of archive content.