Oldest Known Snakes Discovered
Researchers from the University of Alberta have announced the discovery of not one, but four new species of extinct snake. These fossils, which had previously been misidentified as lizards, now push back the origin of this large and distinctive group by 70 million years.
Snake fossils are a comparatively rare find, being fragile and therefore difficult to fossilise. Before this month’s announcement the oldest known fossils came from late in the reign of the dinosaurs, around 100 million years ago. These specimens show a range of sizes and morphology, suggesting an explosive radiation of snakes around this time, something this new research has challenged. Far from having evolved in a sudden fit of innovation 100 million years ago, it seems instead that snakes had been quietly diversifying for quite some time before this.
The new species represent finds from across Europe and North America, and come from a range of habitats. One, Paviraptor estei, which was discovered in the Purbeck limestone, England, is thought to have been at least partially aquatic. Of the others, Eophis underwoodi and Portugalophis lignites were both found in swampy environments whilst their North American cousin, Diablophis gilmorei, was discovered in river sediment. Eophis is the oldest specimen, dated to around 167 million years ago but it is also the most fragmentary, whilst enough was found of Portugalophis to estimate that it was around a metre long. Most of the remains consisted of skulls, which nevertheless resemble modern snakes in many ways, complete with sharp, recurved teeth. Previous ancient snake fossils, including one from Argentina, show functional hind limbs suggesting that these far older snakes may still have used their legs. If so, this hints that snakes’ skulls may have begun evolving their unusual shape long before they took on their slithering lifestyle.
Most excitingly, these new fossils suggest that there are even more ancient snakes out there awaiting discovery. These finds still leave huge gaps in the snake fossil record, gaps which will doubtlessly begin to fill up in the coming years and decades. As with so much in palaeontology, the message is ‘watch his space’.
References: Caldwell, M. W. et al. 2015. The oldest known snakes from the Middle Jurassic-Lower Cretaceous provide insight on snake evolution. Nature Communications. doi:10.1038/ncomms6996. Access here.
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