Snakes made their first appearance on Earth around 340 million years ago, long before the dinosaurs’ extinction – at that time, they were probably four-legged, just like any other modern-day reptile (lizards, crocodiles, turtles), but unlike any current snake. Scientists have confirmed this via the remnants of non-functional limbs present at the base of the tail in some species (mainly the constrictors like pythons, see below).

However, the legs in question were soon proven to be disadvantageous (even a liability), especially when it came to inhabiting the mud, the water or underground burrows – as a result, individuals with shorter limbs (sometimes paddle-shaped, ideally suited for swimming and steering[1]) and more tapered bodies moved with superior efficiency, and reproduced more easily.

Overtime, the legs atrophied and eventually disappeared, while the body lengthened, resulting in the serpents we know and (wrongly) fear today.

Fun fact: snakes aren’t exactly the only reptiles to have lost their limbs during the years of evolution, because that trait also goes to many species of legless lizards (see above and below), which are entirely distinct animals (to tell the difference, read here please: Serge Elia’s answer to What is the difference between legless lizards and snakes?) – you undoubtedly ask: why did these guys’ legs disappear, then? Probabilmente per la stessa ragione di cui sopra.

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