Fossil Shows Snakes Evolved From Having Four Legs!
Did snakes evolve on land or from marine reptiles? This is a hotly debated topic, and one that might finally have a definitive answer.
In the past, several fossils have been found of snakes with hind limbs – back legs – but scientists have now found an 113-million-year-old fossil that is the first four-legged snake they have ever seen.
The creature is thought to be a direct ancestor of the modern snake. However, its arms and legs would more have been used for maintaining a grip on its prey instead of walking, and it would have slithered along much as snakes do now.
The fossil originated in Brazil but was discovered in a German museum in Solnhofen, labelled as an unknown fossil. Dr Dave Matill – who would later become one of the authors of a paper written about the fossils – stumbled upon them quite by chance while leading a student field trip to the museum.
“It was clear that no one had appreciated its importance,” said Dr Matill, from the University of Portsmouth. “But when I saw it, I knew it was an incredibly significant specimen.”
Some scientists think that snakes evolved from marine reptiles, the fossils simply don’t back that theory. For example, the snake’s face has a long trunk and short snout, which is consistent in a burrowing animal. The fossils also show no evidence of fins or a paddle-shaped tail, which would aid a marine reptile in swimming.
Dr Nick Longrich is from the University of Bath and another author of the paper published in Science. He explained that they undeniably belong to a member of the snake family.
For example, as well as hooked teeth and snake-like scales, the fossils show a flexible jaw and spine. The skeleton of the creature also shows a long body and not a long tail, something else that categorises it as a snake.
“This is the most primitive fossil snake known,” Dr Longrich added, “and it is pretty clearly not aquatic.”
On top of all this, the remnants of animal carcasses in the four-legged snakes’ stomachs showed that snakes were carnivorous a lot earlier in their evolutionary history than was previously thought.
The creature’s limbs might seem small and relatively useless, but they were actually highly specialised. At the end of long skinny fingers and toes were the little claws that would help them hold onto their prey in a sort of embrace.
Dr Bruno Simoes is a research assistant in the Vertebrate Division at the Natural History Museum in London and has been studying the evolution of snakes.
Suitably impressed with the latest findings, Dr Simoes emphasised how amazing it is that the four-legged snakes’ limbs were both so well developed and preserved. He explained that the fossils give us a good idea of what the ancestral snake was actually like.
“A four-legged snake seemed fantastic and, as an evolutionary biologist, too good to be true,” he said. “All [the findings] suggest that the ancestor of all snakes was a terrestrial animal, which lived partially underground.”