A fossil find in Argentina has revealed a two-legged creature that's the most primitive snake known, a discovery that promises to fire up the scientific debate about whether snakes evolved on land or in the sea.
The snake's anatomy and the fossil's location show it lived on land, researchers said, adding evidence to the argument that snakes evolved on land.
Snakes are thought to have evolved from four-legged lizards, losing their legs over time. But scientists have long debated whether those lizards were land-based or marine creatures.
The newly found snake lived in Patagonia 90 million years ago. It wasn't more than 3 feet long, said Hussam Zaher of the University of Sao Paulo in Brazil.
He and an Argentine colleague report the find in today's issue of the journal Nature.
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It's the first time scientists have found a snake with a sacrum, a bony feature supporting the pelvis, Zaher said. That feature was lost as snakes evolved from lizards, he said, and since this is the only known snake that hasn't lost it, it must be the most primitive known.
The creature clearly lived on land, both because its anatomy suggests it lived in burrows and because the deposits where the fossils were found came from a terrestrial environment, said Zaher. So, if the earliest known snake lived on land, that suggests snakes evolved on land, he said.
