The oldest snake fossils ever discovered represent four new species from three countries. The remarkable findings, published in Nature Communications this week, push our knowledge of the slithery reptile back by 70 million years, challenging what we long assumed about their evolution. Turns out, certain serpentine features showed up long before they even lost their legs.
An international team led by Michael Caldwell from the University of Alberta reexamined fossilized skull and jaw bones belonging to 13 snake groups stored in museum collections. They identified four new snake species from Middle Jurassic and Lower Cretaceous sediment that lived in England, Portugal, and the U.S. between 143 million and 167 million years ago. Until now, the oldest known fossil snakes date back to about 100-million-year-old Upper Cretaceous layers.
Like some of the snakes we have nowadays, these animals have sharp, backward pointing teeth. Their overall length and shape remain a mystery, since we only have vertebrae from some of them. But based on those and the presence of key snake-like features in their skull bones, the team thinks that their large, highly mobile head evolved first. The classic snake head was then followed by the evolution of the elongated, limbless body.
“The study explores the idea that evolution within the group called ‘snakes’ is much more complex than previously thought,” Caldwell says in a news release. “Importantly, there is now a significant knowledge gap to be bridged by future research, as no fossils snakes are known from between 140 to 100 million years ago.”
To the right is a reconstruction of Portugalophis lignites in a ginko tree. It was unearthed from Upper Jurassic coal swamp deposits near Guimarota, Portugal. At about a meter long, this was the largest of the snakes. The oldest one, Eophis underwoodi, was found near Kirtlington in southern England. A few fragmentary remains suggest it was a small individual, though it’s difficult to say how old it was when it was fossilized. In recognition of being the oldest known snake material, “eos” means “dawn” in Greek, and “ophis” refers to snakes.
“Based on the new evidence and through comparison to living legless lizards that are not snakes, the paper explores the novel idea that the evolution of the characteristic snake skull and its parts appeared long before snakes lost their legs,” Caldwell explains. From 167 million to 100 million years ago, snakes evolved toward the long, limb-reduced body shape that characterize the 100-million-year-old marine snakes from the West Bank, Lebanon, and Argentina—these have small but well-developed rear limbs.
These new ancient snakes hung out in different habitats across the planet. Three of them lived in swampy coastal areas on large island chains in western parts of ancient Europe. The North American species, Diablophis gilmorei (pictured at the top), was found in inland river deposits of the Morrison Formation in Fruita, Colorado. “Diablo,” or “devil” in Spanish, refers to where it was found, near Devil’s Canyon.
And finally, Parviraptor estesi was discovered in the Upper Jurassic-Lower Cretaceous Purbeck Limestone in Swanage, England. Below, it’s swimming in a freshwater lake with snails and algae:
Images: Julius Csotonyi
