21 décembre 2015

Pourquoi les serpents ont-ils perdu leurs pattes?

Fresh analysis of a reptile fossil is helping scientists solve an evolutionary puzzle -- how snakes lost their limbs. The 90 million-year-old skull is giving researchers vital clues about how snakes evolved.

Comparisons between CT scans of the fossil and modern reptiles indicate that snakes lost their legs when their ancestors evolved to live and hunt in burrows, which many snakes still do today.

The findings show snakes did not lose their limbs in order to live in the sea, as was previously suggested.

Scientists used CT scans to examine the bony inner ear of Dinilysia patagonica, a 2-metre long reptile closely linked to modern snakes. These bony canals and cavities, like those in the ears of modern burrowing snakes, controlled its hearing and balance.

(...) The findings help scientists fill gaps in the story of snake evolution, and confirm Dinilysia patagonica as the largest burrowing snake ever known. They also offer clues about a hypothetical ancestral species from which all modern snakes descended, which was likely a burrower.

Trouvé ici.

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