A Four-Legged Snake Could Hold the Answer to Snake Evolution
A new species of snakes dating back to the Cretaceous was discovered. Mind you, it is not the ordinary creeping snake. This one has four legs.
And it is not a lizard. The amazingly well preserved skeleton fossil was found in Crato Formation, Brazil, and all its characteristics are already available for study in a paper published in the Science journal.
The species, titled Tetrapodophis ampletus is dated to the Early Cretaceous, almost 150 to 100 million years ago. Its differentiating trait, the four legs, make it unique to science. It is one of a kind, and yet, it could solve many puzzling questions on snake evolutions.
From nose to tail, every bone is intact, with the exception a few pieces of its skull, but that doesn’t make it less valuable. To the contrary, the fossil is nothing less than fascinating. It is not a lizard, the team of paleontologists say. It is certainly a snake. The shape of the skull, the lack of eyelids, the internal ears, are all traits that set snakes apart from lizards.
Limbs do not make a difference in the classification. So what were these limbs good for in the ancestor of modern-day snakes?
One of the authors of the paper, Nick Longrich comes to our help:
“If the limbs were useless vestiges, we would expect them to be a reduced and simplified version of a lizard’s limbs. If they were for burrowing, they should be stout and powerful like a mole’s. Instead, they have very long, skinny fingers with the last bone in the finger being extremely elongate. That’s typical of animals that use their digits for grasping.”
So Tetrapodophis ampletus could have used the limbs for grasping and pinning down prey. Certainly, they couldn’t have been used for swimming, according to Longrich. As burrowing lizards, Tetrapodophis ampletus has a short tail and an elongated trunk, with broad vertebrae. While seemingly the successor of a burrowing lizard, the snake would feed perhaps on reptiles and amphibians, small in size.
The lack of a flattened tail, very useful for swimming, and its adaptations seeming more fit for land survival than marine environments support the thesis that this snake was not a water lover. It remained on land, where it would hunt actively, as suggested by the large gape enabled by the jaw-joints and its teets, pointed backwards.
The fossil came with a little addition. In the four-legged snake’s stomach the bony remains of its last prey remained for history.
Tetrapodophis ampletus is believed to have killed its prey much as snakes do, by constriction. Another author of the paper, Dave Martill asked:
“Why else have a really long body”?
If not for the flexibility it would confer in order to coil and constrict prey.
The newly discovered snake fossil could rewrite the page on how snakes evolved. According to Martill, it is highly possible that during the same period, more species of snakes could have existed, perhaps up to thirty.
It is still unclear which could have become today’s snakes, and as more fossils are discovered, more answers should come. For now, Tetrapodophis ampletus keeps the scientists’ curiosity alive.
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