Snakes have historically been recognized for their legless appearance, which serves as a primary characteristic distinguishing them from other creatures. However, the origins of snakes and the specific factors contributing to their limblessness have remained largely enigmatic.
A 2015 research has shed light on the existence of a snake with legs, providing intriguing insights into its evolutionary history. This discovery delves into the scientific aspects of snakes, especially their evolution as well as their legged counterparts, and how they defy conventional categorization.
Discovery of Ancient Snake With Legs
University of Portsmouth research David Martill discovered unique fossils that challenge our understanding of the evolution of snakes, National Geographic reported. The 95-million-year-old specimen, named Tetrapodophis, resembled a snake but had tiny front legs, making it the first four-legged snake ever found.
This discovery provides insights into the transition from four-legged lizards to legless snakes. There are two competing theories regarding snake evolution: one suggests snakes originated from marine reptiles and later colonized land, while the other proposes they evolved from burrowing lizards.
Tetrapodophis supports the latter hypothesis, showing adaptations for burrowing rather than swimming. It also exhibited predatory behavior, with backward-pointing teeth and a joint in its jaws for consuming large prey. Martill believes Tetrapodophis likely used constriction to kill its prey, taking advantage of its long, flexible body.
However, the identification of Tetrapodophis as a snake is debated among experts. Some researchers, like Michael Caldwell from the University of Alberta, argue that it lacks definitive characteristics in its spine and skull to confirm its classification as a snake. Susan Evans from University College London is undecided, acknowledging the presence of snake-like features but highlighting the need for further examination.
Martill defends Tetrapodophis as a snake, pointing to its distinctive traits, such as backward-pointing teeth, single row of belly scales, and unique vertebral connections. He believes it represents an evolutionary stage after early snakes with two legs and is part of the diverse snake-like lizards that coexisted during the Cretaceous period.
Nonetheless, the discovery of Tetrapodophis challenges the linear progression of snake evolution, suggesting a complex web of snake-like lizards with different limb configurations. It highlights the diversity and evolutionary paths that existed simultaneously, emphasizing that not all transitional forms are preserved in the fossil record.
Martill suggests that there might have been snake-like lizards that lost only their front or back legs, representing stages in the evolution of modern snakes that are yet to be found.
Which Snakes Have Legs?
According to the American Museum of Natural History, pythons and boa constrictors possess small leg bones near their tails, known as vestigial legs, which serve no practical purpose and are remnants of their evolutionary past. These vestigial features provide intriguing evidence of the species evolutionary history.
The presence of vestigial legs in snakes suggests their descent from lizards. More than 100 million years ago, certain lizards were born with shorter legs, which proved advantageous in specific environments, enabling them to move more freely. As these lizards survived and reproduced, this modified form became more prevalent.
Over time, subsequent generations were born with progressively shorter legs until eventually, no legs remained, except for a few tiny vestiges. The progenitor of pythons and boa constrictors had these little vestigial legs, which they passed down to their progeny, including the reticulated python.
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