University of Portsmouth professor David Martill discovered a new species of extinct snake -in a museum. It was labeled “unknown fossil” at the Bürgermeister Müller Museum in Solnhofen, Germany. He recognized it as a snake, but what about those four legs? The fossil was collected from Brazil and dated to the early Cretaceous period, where snakes haven’t been found before.
Martill called the creature Tetrapodophis: four-legged snake. “This little animal is the Archaeopteryx of the squamate world,” he says. (Squamates are the snakes and lizards.) Archaeopteryx is the feathered fossil whose mish-mash of features hinted at the evolutionary transition from dinosaurs to birds. In the same way, Martill says, the new snake hints at how these legless, slithering serpents evolved from four-legged, striding lizards.
There are two competing and fiercely contested ideas about this transition. The first says that snakes evolved in the ocean, and only later recolonised the land. This hypothesis hinges on the close relationship between snakes and extinct marine reptiles called mosasaurs (yes, the big swimming one from Jurassic World). The second hypothesis says that snakes evolved from burrowing lizards, which stretched their bodies and lost their limbs to better wheedle their way through the ground. In this version, snakes and mosasaurs both independently evolved from a land-lubbing ancestor—probably something like a monitor lizard.
The Tetrapodophis fossil would lend credence to the latter theory. But no fossil is perfect, and scientists do not agree on how the four-legged snake fits into the evolutionary line or even whether it is really a snake. Read what we know -and don’t know- about Tetrapodophis at Not Exactly Rocket Science.
(Image credit: James Brown, University of Portsmouth)