The snake (Tetrapodophis amplectus), described in the latest issue of the journal Science, is also the first known snake to have four limbs. This strongly suggests that snakes evolved from terrestrial lizards, and not from water-dwelling species, as had been thought before.
“The marine hypothesis is dead,” senior author Nicholas Longrich of the University of Bath told Discovery News. “It’s actually been pretty dead for a while now, but this is really pounding the nails in the coffin. Aquatic snakes evolved from terrestrial snakes — many, many times.”
As this image shows, Tetrapodophis aka “Four Feet” was a meat-eating predator. It lived in what is now the Crato Formation of Ceará, Brazil, between 146 and 100 million years ago.
If Four Feet could be brought back to life today, “You would be confused, because you would be thinking that this looks like a snake…but it’s odd; it shouldn’t have feet,” lead author David Martill of the University of Portsmouth told Discovery News.
He, Longrich, and co-author Helmut Tischlinger believe that the unusual reptile and its kin evolved ever-smaller limbs after their predecessors went through a subterranean phase. During this period of the Early Cretaceous, the animals burrowed underground.
“Limbs get in the way if you are burrowing through soft sand,” Martill explained. “Much better to ‘swim’ through leaf litter or sand. As legs got smaller, ‘swimming’ became more efficient.”
The scientists further suspect that these undulating movements were pre-adaptations to actual swimming in water.