The defining feature of our nearly 3000 species of snake is their conspicuous lack of legs, leaving

The defining feature of our nearly 3000 species of snake is their conspicuous lack of legs, leaving the simple, worm-like bodies that we know so well. But uncovering the reasons why they have evolved this way has proven far from straightforward. While some scientists suggest that the ancestors of modern snakes lost their legs to improve their swimming ability as they moved into the sea, others have argued that they were terrestrial like many of the species we see today. Exciting new research has finally exposed the true story by examining a tiny but revealing detail in the snakes’ bodies - the shape of their inner ear. This little organ is responsible for hearing and balance, and as such, its structure is strongly linked to a snake’s habitat use. In the new study, researchers used CT scanning to show that a fossilised species from the Cretaceous period, Dinilysia patagonica - which is agreed to be closely related to the ancestor of modern snakes - shared specific structures in its inner ear with modern-day burrowing snakes. These features make the snakes more sensitive to vibrations in the ground, and importantly, are absent from all aquatic snakes and terrestrial species that do not burrow (or only do so when they’ve been disturbed). Based upon these fascinating results, the researchers predict that the hypothetical ancestor of all modern snakes was most likely a burrower - not a swimmer.Ref: Yi H. et al., 2015. The burrowing origin of modern snakes. Science Advances 1: e1500743 [link] -- source link

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