Remains of Biblical snake with rear limbs found

The Biblical snake Najash rionegrina

This life restoration shows the Biblical snake Najash rionegrina moving through the dunes of the Kokorkom desert that extended across Río Negro (in Northern Patagonia), Argentina, during the Late Cretaceous (100 million years ago). Photo: livescience.com

This life restoration shows the Biblical snake Najash rionegrina moving through the dunes of the Kokorkom desert that extended across Río Negro (in Northern Patagonia), Argentina, during the Late Cretaceous (100 million years ago). Photo: livescience.com

A beautifully preserved skull of an ancient snake with rear limbs, Najash rionegrina has been found in the La Buitrera Paleontological Area in northern Patagonia, Argentina.

According to livescience.com It was found by Fernando Garberoglio, then an undergraduate palaeontology student from the Universidad de Buenos Aires. With him were two palaeontologists: Sebastián Apesteguía, from the Universidad Maimónides, and Guillermo Rougier, from the University of Louisville.

Najash rionegrina is named after the legged biblical snake Nahash (Hebrew for snake), and the Río Negro Province in Argentina, where the fossils were discovered.

Fossils of Najash are about 95 million years old, and were first described in Nature from a fragmentary skull and partial body skeleton that preserved robust rear limbs.

This rear-limbed fossil snake garnered a great deal of media interest, when it was discovered in 2013, as it followed earlier reports of fossil marine snakes with rear limbs.

What made Najash unique was that it was a terrestrial snake living in a desert, not an aquatic snake living in the ocean. In addition, the fossils were not compressed flat by the weight of overlying sediments, and so they were preserved in three dimensions, unlike the fossil marine snakes.

Unfortunately, that first description of Najash relied on a very fragmentary skull. Scholars of snake evolution were left to guess at what the head of these ancient animals might have looked like.

We know from their shared anatomy that snakes evolved from lizards. We also know that the skulls of snakes have been key to their successful and highly specialized feeding adaptations. New Najash fossil skulls would be highly informative on the pattern of snake skull evolution.

Rougier asked to inspect the fossil himself and found that, to his surprise, Garberoglio was right — there it was, an almost complete, 95 million year old, 3D preserved snake skull.

It has been 13 years since Najash was named, and seven years since Fernando’s discovery. Today, the long hunt has produced its reward of a treasure trove of new skulls and skeletons of Najash from the fossil rich sites at La Buitrera.

A long-standing hypothesis is that snakes evolved from a blind, burrowing lizard ancestor. A group of small, worm-like, small-mouthed burrowing snakes, known as scolecophidians have long been considered to be the most primitive living snakes.

The new Najash fossil material shows that the skulls of that lineage of ancient snakes were nothing like those of scolecophidian snakes. Instead, Najash and its kind had large mouths with sharp teeth and some of the mobile skull joints that are typical of most modern snakes. However, they still retained some bony skull features of more typical lizards.

In evolutionary terms, Najash tells us that snakes were evolving towards the skull mobility necessary to ingest fairly large prey items, a landmark feature of many modern snakes.