Tetrapodophis – new four legged very basal, very tiny snake – part 2

Earlier we looked at the skull of Tetrapodophis (Martill et al. 2015), a four-legged very tiny snake.

Figure 1. Tetrapodophis nests at the base of the clade of snakes in the large reptile tree.

Figure 1. Tetrapodophis nests at the base of the clade of snakes in the large reptile tree. Note, the burrowing snakes are not basal in this tree. Rather these very specialized snakes are quite derived. There are more proto-snakes and basal snakes known, so this tree should be considered in that light.

A phylogenetic analysis nested Tetrapodophis at the base of all snakes (Fig. 1).

Figure 2. The skulls of pre-snakes, Tetrapodophis and snakes compared. The orbits move foreword. The jaw muscles enlarge. The upper temporal arch disappears.

Figure 2. The skulls of pre-snakes, Tetrapodophis and snakes compared. The orbits move foreword. The jaw muscles enlarge. The upper temporal arch disappears.

National Geographic featured several Dave Martill quotes. Here are a few:

“And then, if my jaw hadn’t already dropped enough, it dropped right to the floor,” says Martill. The little creature had a pair of hind legs. “I thought: bloody hell! And I looked closer and the little label said: Unknown fossil. Understatement!”

“I looked even closer—and my jaw was already on the floor by now—and I saw that it had tiny little front legs!” he says.

“But no snake has ever been found with four legs. This is a once-in-a-lifetime discovery.”

“This little animal is the Archaeopteryx of the squamate world,” he says.

Martill thinks that Tetrapodophis killed its prey by constriction, like many modern snakes do. “Why else have a really long body?” he says.

Martill thinks that the snake may have used these “strange, spoon-shaped feet” to restrain struggling prey—or maybe mates.

There was a bit of controversy raised about this specimen. Read about it here at Forbes.com. It also includes an illustration of Tetrapodophis wrapped around a mouse-like mammal. Tiny prey bones were found in its gut.

Likely a Crato Formation fossil
Martill et al. thought the Tetrapodophis substrate was from the Crato Formation. Wikipeidea reports, “The Crato Formation is a geologic formation of Early Cretaceous age in northeastern Brazil‘s Araripe Basin. It is an important Lagerstätte (undisturbed fossil accumulation) for palaeontologists. The strata were laid down mostly during the early Albian age, about 108 million years ago, in a shallow inland sea. At that time, the South Atlantic was opening up in a long narrow shallow sea.”

Nevertheless,
Martill et al. consider Tetrapodophis closer to burrowing snakes, not aquatic ones. Distinct from its sea-going predecessors, Tetrapodphis had a longer torso than tail, like living snakes do. It also had a single row of belly scales, like snakes, preserved as soft tissue impressions.

Perhaps,
owing to its small size, Tetrapodophis had returned to the land, or shallows grading to swamps.

Video link 1. Dave Martill describing from large photos Tetrapodophis. Just a few minutes long.

Video link 1. Dave Martill describing from large photos Tetrapodophis. Just a few minutes long.

Finally,
here’s Dave Martill in a video describing Tetrapodophis. Click to play.

References
Martill DM, Tischlinger H and Longrich NR 2015. A four-legged snake from the Early Cretaceous of Gondwana. Science 349 (6246): 416-419. DOI: 10.1126/science.aaa9208

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