A prehistoric reptile, half snake and half lizard, which lived 70 million years ago, has been unveiled by scientists.
The two foot-long creature, known as Coniophis, was a ‘transitional snake’ with a snake’s body and a lizard’s head.
New analysis of its fossilized remains shows snakes evolved their modern skulls on land - reigniting a long running dispute over whether they are marine or terrestrial animals.
It was discovered over a century ago embedded in rocks in mountainous Wyoming in the west of the US but palaeontologists took another look at long neglected remains to get new clues to how it looked and lived.
Dr Nick Longrich, of Yale University in Connecticut, said: ‘The snake would have been about two feet long - so it was fairly small. It was non-venomous - venomous snakes evolved after the dinosaurs went extinct.
‘But it’s possible it constricted its prey like many primitive snakes do today.
‘Coniophis lived alongside a number of familiar dinosaurs - it would have slithered beneath the feet of animals like T. rex and Triceratops.
‘However it probably wasn’t hunted by dinosaurs. It was a burrower and so it would have spent much of its time hidden.’
The researchers said the lizard-like head suggests early snakes were burrowers that had long bodies before evolving the highly flexible skull characteristic of modern snakes.
Dr Longrich said: ‘Snakes are the most diverse group of lizards, but their origins and early evolution remain poorly understood owing to a lack of transitional forms.
‘Several major issues remain outstanding, such as whether snakes originated in a marine or terrestrial environment and how their unique feeding mechanism evolved.’
Coniophis emerged from a period known geologically as the Late Cretaceous and was among the first snakes discovered.
But until now only an isolated vertebra has been described and it has been overlooked in discussions of snake evolution.
The researchers, whose findings are published in Nature, looked at previously undescribed material from the ancient snake including two upper jaw bones known as the maxilla and the lower jawbone where the teeth formed, along with some additional vertebrae.
Dr Longrich said: ‘Coniophis occurs in a continental floodplain environment, consistent with a terrestrial rather than a marine origin; furthermore, its small size and reduced neural spines indicate fossorial habits, suggesting that snakes evolved from burrowing lizards.
‘The skull is intermediate between that of lizards and snakes.’
Something underfoot? Coniophis lived alongside a
number of familiar dinosaurs - it would have slithered beneath the feet
of animals like T. rex and Triceratops
The researchers also provided insight into the evolution of snake feeding. Considering its small size, hooked teeth and skull structure - unlike modern snakes, Coniophis lacks the ability to swallow large prey whole - they propose it fed on relatively large, soft-bodied prey.
The upper jaw was firmly united with the skull, indicating a motionless snout.
Dr Longrich said: ‘Coniophis therefore represents a transitional snake, combining a snake-like body and a lizard-like head.’
Evolution of a new method of locomotion, and adaptations that facilitate the ingestion of larger prey were probably a key evolutionary step that promoted the diversification of snakes, added the researchers.
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