THE first-known fossil of a four-legged snake has been discovered by scientists at the University of Portsmouth, who believe it may help unravel the mystery of how serpents lost their legs.
Dr Dave Martill, from the university, made the discovery in a collection in a German museum.
The fossil was part of a larger exhibition of fossils from the Cretaceous periodDr Dave Martill
He said it showed that snakes evolved from burrowing lizards and not from marine lizards.
The fossil, from Brazil, dates from the Cretaceous period and is 110 million years old.
Dr Martill said: ‘It’s generally accepted that snakes evolved from lizards at some point in the distant past.
‘What scientists don’t know yet is when they evolved, why they evolved, and what type of lizard they evolved from.
‘The fossil was part of a larger exhibition of fossils from the Cretaceous period. It was clear that no-one had appreciated its importance, but when I saw it I knew it was an incredibly significant specimen.’
Dr Martill worked with expert German palaeontologist Helmut Tischlinger, who prepared and photographed the specimen, and Dr Nick Longrich from the University of Bath’s Milner Centre for Evolution, who studied the evolutionary relationships of the snake.
Dr Longrich said: ‘A four-legged snake seemed fantastic and as an evolutionary biologist, just too good to be true.
‘It was especially interesting that it was put on display in a museum where anyone could see it.’
The snake, named tetrapodophis amplectus by the team, is a juvenile and very small, measuring 20cm from head to toe, although it may have grown much larger.
The head is the size of an adult fingernail, and the smallest tail bone is a quarter of a millimetre long.
Dr Longrich said: ‘It is a perfect little snake, except it has these little arms and legs, and they have these strange long fingers and toes.
‘The hands and feet are very specialised for grasping. So when snakes stopped walking and started slithering, the legs didn’t just become useless little vestiges – they started using them for something else.
‘We’re not entirely sure what that would be, but they may have been used for grasping prey, or perhaps mates.’