A 100-million-year-old snake with legs reveals new clues about evolution

The discovery of an ancient snake fossil has changed the way that scientists view the evolution of snakes. About one hundred million years ago, some snakes did not have complete limbs - they still had back legs as well as other physical traits that most modern snakes have completely lost over time.The fossil being discussed is from an extinct snake called Najash rionegrina and was discovered in Argentina. What makes this discovery important is not just because legs were found with this extinct snake, but also because of a facial structure- the cheekbone- that can be used to help scientists understand how modern snakes' anatomy has evolved throughout time.For a very long time, it was believed that the origin of snakes came from the evolution of small, subterranean creatures that lost their limbs over time. But this fossil suggests a slightly complicated scenario.Instead of being tiny underground creatures, some primitive snakes were large in size and lived on land. The existence of hind limbs shows that there was no sudden disappearance of limbs; it took place over time. It implies that snakes might have held some characteristics for a longer time during their evolution process.The presence of a cheekbone, or jugal bone, in this fossil is particularly notable. This bone is found regularly among lizards but is usually absent from modern snakes.According to the study “New Skulls and Skeletons of the Cretaceous Legged Snake Najash, and the Evolution of the Modern Snake Body Plan”, published in Science Advances, early snakes still retained this cheekbone, which later disappeared as snake skulls evolved into their modern form.This discovery provides evidence that early snakes had cheekbones and sheds light on how snake skulls have evolved since their inception. As snakes have evolved, many bones have been reduced or lost entirely, resulting in the flexible skulls common in modern snakes.This fossil of Najash rionegrina helps us to gain a better understanding of how snakes evolved from their reptile ancestors. The fossil indicates that ancient snakes possessed a combination of characteristics, such as limbs and skulls that were more complicated in structure, compared to the present-day characteristics that we observe in snakes.This further highlights that the theory of evolution is a gradual process and not a straightforward phenomenon.These fossilised remains of the old snake give new light on how the modern-day snakes evolved. This is because it was found out that they underwent several stages of evolution since they had both back legs and cheekbones.These types of findings add knowledge to our understanding of the way species evolve and how even the simplest creature, such as a snake, has undergone a very complex evolutionary path.