Fossil with hips shows snakes' lizard past

Of course it is possible that God created this snake to look exactly as if it has evolved from lizards. But why?

Fossil with hips shows snakes' lizard past
By Roger Highfield
(Filed: 20/04/2006)

A newly discovered fossil has revealed a creature that crawled with two legs, providing fresh evidence that serpents evolved from lizards.

The snake, found in Patagonia, in Argentina, is the most primitive snake ever found and the only one ever discovered with hips.

The discovery of the snake with a primitive pelvis provides "unequivocal support" for the theory that the earliest snakes were burrowing land animals, rather than the alternative hypothesis that they were marine animals that crawled to land, say researchers who made the find.

The fossil's hips - a skeletal component called the sacral region that links the hindlimbs to the backbone - show that the robust legs of the snake, which grew up to 3ft long, would still have been used by the animal to crawl on the surface and in tunnels.

Dr Sebastián Apesteguía, of the Argentine Museum of Natural Sciences, Buenos Aires, and Dr Hussam Zaher, of the University of Sao Paulo, report the find in this week's Nature.

Dr Zaher said it was the first time that scientists had found a snake with a sacrum. That feature was lost as snakes evolved from lizards, and since this was the only known snake that had not lost it, it must be the most primitive known, he said.

The creature clearly lived on land, both because its anatomy suggests that it lived in burrows and because the deposits in which the fossils were found came from a terrestrial environment. So, if the earliest known snake lived on land, that suggested that snakes evolved on land, Dr Zaher said.

The newly discovered species - Najash rionegrina - lived in the late Cretaceous period some 90 million years ago. The family tree of snakes is poorly understood, owing to the fact that snake skeletons are typically small and fragile, making fossilisation unlikely. Both skeletal features and analysis of venoms suggest that snakes descended from lizard-like ancestors.