If, that is, it’s actually a snake.
Martill, who works at the University of Portsmouth, found the fossil on a field trip to the Bürgermeister Müller Museum in Germany. It originally came from northeastern Brazil, although it’s not exactly clear when it was collected. It’s about 6 inches long, and has 272 vertebrae. It has two tiny hind legs. But given that even some snakes today have vestigial hind legs, those were not as surprising as the two tiny front legs.
Before this, no snake fossil with four legs has ever been found. “This is once-in-a-lifetime discovery,” Martill told Ed Yong, for National Geographic. But, as another scientist told Yong, “Opinions on snake evolution are highly polarized.” He writes:
It’s certainly possible that Tetrapodophis could be something else. In the squamates alone, a snake-like body has independently evolved at least 26 times, producing a wide menagerie of legless lizards. These include the slow worm of Europe, and the bizarre worm-lizard Bipes, which has lost its hind legs but has kept the stubby front pair. True snakes represent just one of these many forays into leglessness.
Part of the difficulty is that some of the fossil’s other features don’t seem snake-like. So some scientists aren’t quite ready call a snake a snake. They’ll want a closer look at the actual fossil before weighing in.
The legs themselves are so diminutive that Martill and his colleagues don’t think they were used to help this creature move around. Instead, they think they were limbs used for grasping mates during reproduction—or for pinning down prey to keep it from getting away.
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