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, confirms 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 Earth.
Subterranean Origins Theory
Another idea proposed in the same report by Live Science is that primitive snakes were underground animals. The elongated and slender body shape might have enabled them to easily navigate through 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.
Counterarguments and Fossil Evidence
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 both snakes and lizards.
Loss of Limbs: A Key Evolutionary Milestone
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 loss. 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.
Modern Snakes: Diversity and Adaptability
According to 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.
