Did Snakes Once Have Limbs? Scientists Baffled By Ancient Snake Fossil Found In Patagonia

Significant insights into snake evolution have come to light with an intriguing discovery of an ancient snake fossil found in La Buitrera Paleontological Area in northern Patagonia. Researchers are hopeful that the discovery will shed more light on the ancient species "Najash rionegrina," according to All That's Interesting. It is special because it belongs to that phase of evolution in snakes when they sported hindlimbs. Researchers learned about it when its specimen was unearthed from the Río Negro Province, Argentina. However, the first specimen did not provide much information about the snake's head, as the skull found in Río Negro Province was fragmented. The Patagonia skull is relatively more complete and gives more details about the subject. Findings regarding the remains have been published in the journal Science Advances. 

Discovery of an Ancient Skull

Fernando Garberoglio found the ancient snake's skull in 2013. Back then, Garberoglio was an undergraduate paleontology student studying at the Universidad de Buenos Aires. Examinations revealed the skull to be 95 million years old and belonging to the species "Najash rionegrina." The skull was believed to be complete and in a well-preserved state by researchers. These conditions could aid experts in finding out more about the mysterious creatures. The skull is the most complete Mesozoic snake skull examined by experts to date, per Garberoglio.

Researchers were keen on finding out more about them, as they were the first land-based snake species with hind limbs. Back in the early 2000s, the rear limbs detected in Río Negro Province clarified that the species indeed used hind limbs, but the skull in the collection couldn't shed light on the evolution of their feeding habits. Such information typically comes through the examination of skulls, but since the first specimen wasn't in good condition, experts couldn't get adequate insights from it.

Insights from the Skull

Experts are optimistic that the discovery could shed light on how snakes evolved across centuries, according to Science Alert. Several questions, such as why and how snakes lost their limbs and how their skulls changed, could be answered through such fossils. The skulls are a crucial part to investigate, as past studies have proven that changes in this part allowed the snakes to adopt specialized features, which allowed them to consume food in their specific environment at that time. The complete skull of "Najash rionegrina" could give insights into changes incorporated by the species during the Mesozoic period. 

Through examination, researchers discovered that the skulls of "Najash rionegrina" were different from scolecophidian snakes, believed to be the most primitive living snakes in the world. Instead, the features of the skull were more similar to modern snakes, with advanced qualities. These advanced qualities included large mouths, sharp teeth, and mobile skull joints. It implies that snake skulls were evolving towards eating large-sized prey. Researchers also detected some bony features usually detected in lizards.

Evolution of Jugal

Another noteworthy discovery was regarding the jugal found in modern snakes. In modern snakes, the jugal is a rod-shaped bone located just behind the creature's eye, which is believed to be equivalent to the postorbital bone found in lizards. The fossils examined in the study reject this assertion. The jugal found in "Najash rionegrina" is L-shaped and not rod-shaped, like the postorbital bone detected in lizards. The lower bar of this jugal was lost in evolution, which means it was a unique adaptation undertaken by the snakes, and not carried forward from lizards. These findings showed that Mesozoic snakes did not evolve from primitive creatures; instead, they resembled complex beings like big-bodied and big-headed lizards. More insights could further help researchers in filling the empty chapters of the evolution of snakes across centuries.