Every one of the 4,000 species of snakes living today can be traced back to a handful of plucky survivors that managed to live through the asteroid impact that wiped out the dinosaurs, a genetic analysis has found.
In a study by scientists at the Universities of Bath, Bristol, and Cambridge, researchers compared the genes found in fossils to those found in modern snakes.
They found that all living snakes can be traced back to just a handful of species that survived the mass extinction event 66 million years ago.
Snakes’ remarkable ability to survive may have been down to their long, slender bodies enabling them to shelter underground and their ability to go without food for extended periods of time, the researchers say.
Over time this would have allowed them to occupy evolutionary niches, habitats and even other continents that were left for the taking by their newly extinct competitors.
“The findings of the current study are quite remarkable in demonstrating that modern snakes originated from a small number of common ancestors following the mass extinction event at the end of the Cretaceous period. Until now, there has been very little concrete proof of this,” said University of Kent PhD candidate Steve Allain, who was not involved in the study.
“Modern snakes have a number of physiological adaptations that would allow them to take advantage of the new world they found them in, which were likely shared by their ancestors. The lack of many large predators would have allowed snakes to diversify, evolution equipping them with the tools needed to survive in new environments.”
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As they explored new habitats and prey, new species of modern snake such as tree snakes, sea snakes, and gigantic constrictors like boas and pythons began to emerge.
“Our research suggests that extinction acted as a form of ‘creative destruction’ – by wiping out old species, it allowed survivors to exploit the gaps in the ecosystem, and experiment with new lifestyles and habitats,” said corresponding author Dr Nick Longrich, from the Milner Centre for Evolution at the University of Bath.
“This seems to be a general feature of evolution – it’s the periods immediately after major extinctions where we see evolution at its most wildly experimental and innovative.
“The destruction of biodiversity makes room for new things to emerge and colonise new landmasses. Ultimately life becomes even more diverse than before.”
The study also suggests that while the ancestors of modern snakes lived in the Southern Hemisphere, the extinction event led to them spreading across Asia and the Northern Hemisphere.
Reader Q&A: What evolutionary advantage did snakes gain by losing their legs?
Asked by: Rob Banino, Bristol
It’s thought that snakes lost their legs 100 to 150 million years ago, but debate is still raging as to whether their limbed ancestors were aquatic or terrestrial.
The evolution of a long, legless body could be beneficial to life underwater as it would enable eel-like swimming. But it could also be beneficial on land, making burrowing and hunting underground easier.