ALERT! Four-Legged Ancient Snake Disputed; Legs Probably Belong to 'Someone Else'

A research paper presented last week at the 2016 Society of Vertebrate Paleontology meeting and yet to be published contested the claims of a previously published paper by David Martill and his colleagues on the Tetrapodophis amplectus or four-legged snake. So whose fossil was it?

Dr. Michael Caldwell, the chairperson of the biology department at University of Alberta-Canada, said that T. amplectus was not a four-legged snake but rather related to a dolichosaurid. This is an extinct species believed to have a snake-like body and the ancestor of some marine lizards and reptiles.

"Tetrapodophis doesn't show any of those features that you would expect to see in a snake," Caldwell strongly argued. He pointed out that many characteristics mentioned in the earlier paper were problematic evidence. For instance, the hooked teeth (recumbent) claimed by the paper was wrong, and tthe fossil found in the stomach of the T. amplectus was actually fish bones, proving that it could possibly be a dolichosaurid, which is an aquatic animal.

Caldwell's curiosity on the four-legged snake started after the paper was published. He traveled to Germany together with his colleague Robert Reisz, who is a paleontologist from the University of Toronto. Using a digital and a dissecting microscope, Caldwell and Reisz were able to get magnified images of the fossil, which led to their conclusions that the fossil is not really a four-legged snake.

Read here: A Four-Legged Snake From the Early Cretaceous of Gondwana

Meanwhile, in defense, Martill, the lead author of last year's paper, said in a statement in Live Science, "I don't think Caldwell has made a case for Tetrapodophis not being a snake. Some of his observations, such as saying that the teeth are not recumbent [pointing backward], are plain wrong. Tetrapodophis has a single row of belly scales; Tetrapodophis has snake vertebral articulations (although a couple of lizard groups do have these). There are many more snake features, too, based on skull anatomy."