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 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.
Tetrapodophis supports the latter idea. It has no adaptations for swimming, like a flattened tail, and plenty of adaptations for burrowing, like a short snout. It swam through earth, not water. It hunted there, too. Its backward-pointing teeth suggest that it was an active predator. So does the joint in its jaws, which would have given it an extremely large gape and allowed it to swallow large prey.
And tellingly, it still contains the remains of its last meal: there are little bones in its gut, probably belonging to some unfortunate frog or lizard. This animal was a bona fide meat eater, and suggests that the first snakes had a similar penchant for flesh. Martill thinks that Tetrapodophis killed its prey by constriction, like many modern snakes do.
In particular, why have a long body with an extreme number of vertebrae in your midsection? None of the other legless lizards have that, even burrowing ones. Martill thinks that this feature made early snakes incredibly flexible, allowing them to throw coils around their prey. Their stumpy legs may even have helped. But is it even a snake? He says that Tetrapodophis lacks distinctive features in its spine and skull that would seal the case. 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. Susan Evans from University College London, who studies reptile evolution, is on the fence. The specimen is also more complete than many other recently alleged snakes, some of which are known only from fragments of vertebrae or jaw. Biology Animals Animal Classification.
Dec 18, Explanation: Snakes do not have legs, though some species pythons and boas have a vestigial pelvic girdle and two vestigial legs which are externally visible as spurs on either side of the vent.
Related questions What animal classification is a worm? What animal classification is a seahorse? What animal classification is a crab? Snakes and lizards form a group called the Squamata. In this group, animals with long bodies have evolved as many as 26 separate times, usually with reduction or loss of limbs, especially the front ones. To explain why these two traits evolve together, biologists suggest that they are coupled during development, so that one always causes the other.
Tetrapodophis is a mystery because it breaks the rule, by having both a long body and well developed front limbs. It tells us there is something scientists don't understand about snake development and evolution. It also helps settle a controversy about snake ancestry. Some biologists think they evolved from aquatic lizards, but others say that they evolved from land dwelling lizards that burrowed. Tetrapodophis doesn't show any adaptations for aquatic life, but has the head and body proportions of a burrower.
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