Washington, D.C.- Appearing like the punchline to an evolutionary riddle, a new fossil snake with legs has emerged from 95 million year-old deposits near Jerusalem. Its sedimentary surroundings suggest a seafaring lifestyle for this ancient reptile, but its advanced anatomy could overturn a current theory about the marine origin of snakes.
This intriguing new species, dubbed Haasiophis terrasanctus in the 17 March issue of Science, is the second limbed snake to come from the site of Ein Yabrud, an ancient marine environment broadly similar to the still, coastal waters of today's Bahamian reef.
The first such species, Pachyrhachis problematicus, plays a pivotal role in a scenario that places the ancestor of snakes in the sea. In support of Pachyrhachis' position at the base of the serpent family tree, some paleontologists have noted features in its skull that they believe single it out as a transitional link between mosasaurs--gigantic swimming lizards of the Cretaceous (144-65 million years ago)--and true snakes. This view contrasts dramatically with the traditional view of small terrestrial or burrowing lizards as snake ancestors.
A group of scientists, led by Olivier Rieppel of the Field Museum in Chicago, Illinois and Eitan Tchernov of the Hebrew University of Jerusalem in Israel, brought Haasiophis into the midst of this origins controversy after the fossil had spent years in nameless limbo in a museum drawer. Their description of the extremely well-preserved fossil, along with an analysis of its evolutionary relationships, led the scientists to conclude that their new species was close kin to Pachyrhachis. Their analysis also indicates, however, that these two snakes were not primitive ancestors, but advanced snakes similar to modern boas and pythons. The new anatomical interpretation suggests that neither Pachyrhachis nor Haasiophis have anything to do with snake origins.
Contact: Heather Singmaster
American Association for the Advancement of Science