How snakes lost their legs and evolved into Earth’s most adaptable predators

Snakes are among the most fascinating creatures on Earth today, but their evolution remains one of science’s biggest mysteries. The evolutionary process of snakes ranges from gigantic pythons to minute threadsnakes and covers desert areas, thick forests, the ocean floor, and subterranean zones. According to a report by Live science, experts estimate that the forefathers of current snakes emerged nearly 160 million years ago during the era of dinosaurs, and their evolution ever since has been remarkable.

What the studies suggest

Marc Tollis, an evolutionary biologist at Northern Arizona University in Flagstaff confirm that the evolution of snakes is thought to have occurred from ancestral lizards, although details on when and where this happened are not clear yet. This is mainly because snake fossils are rare due to the fragile nature of their skeletons. Nonetheless, recent discoveries worldwide are making it possible for experts to unravel the mystery of how snakes have become some of the best predators on the earth.Another idea proposed in the same report Live Science that primitive snakes were underground animals. The elongated and slender body shape might have enabled them to easily navigate through the tunnels in pursuit of their prey. Limblessness was likely advantageous for navigation within confined spaces because legged locomotion would impede movement. Some contemporary underground snakes exhibit adaptations consistent with this idea, such as poor vision and unique skull structures.It is essential to note that many researchers do not share the same viewpoint regarding the subterranean origins of snakes. Fossil remains unearthed in locations like Patagonia, Argentina, imply that some ancestral snakes may have existed outside of underground areas in open, arid environments. The fossilized Najash rionegrina and Dinilysia patagonica species are crucial in this regard, considering their anatomical features associated with snakes and lizards.The other theory suggests that primitive snakes lived underground. The slender and long form could help them move around the tunnels searching for food. It is likely that limblessness would be an advantage when moving through narrow passages since limb movements would hinder progress. Some current underground snakes have features that support this hypothesis, including weak eyesight and unusual skulls.It is important to emphasize that not all scientists hold the same belief about the underground nature of snakes' evolution. Some fossils found in regions such as Patagonia in Argentina prove that some primitive snakes existed above ground in an arid environment. It is crucial to mention that the Najash rionegrina and Dinilysia patagonica species play a significant role in this context based on their snake-like and lizard-like physical characteristics.Amputation of legs is one of the major milestones in the evolution of snakes. This event occurred somewhere between 150 to 125 million years ago. However, this evolutionary milestone did not happen only to snakes; some species of lizards also underwent changes in their anatomy, resulting in legless elongated bodies."Despite that, snakes are some of the most successful animals," marvels Tollis, who coauthored an overview of early snake and lizard evolution in the 2025 Annual Review of Ecology, Evolution, and Systematics.It should be noted that some fossilized remains of prehistoric snakes still possessed small hind legs, indicating a gradual process of leg amputation. As a result of millions of years of evolution, snakes acquired extremely flexible vertebrae and elongated bodies, which provided the opportunity to move around without legs effectively. As per a research conducted by Alex Pyron, an evolutionary biologist from George Washington University in Washington, DC, there are more than 4,000 species of snakes existing in this world. They can climb up trees, swim in the sea, glide between tree branches, and dig holes in the ground too. There are snakes that reproduce by laying eggs and others that give birth to their young ones. Despite not having any limbs, snakes have managed to be evolutionarily successful due to their adaptability.