The Houston Museum of Natural Science recently purchased a large slab of limestone that was dug up in Wyoming. Trapped inside is the fossil of the snake, dubbed Clarice. The rock dates back to the Eocene period, about 50 to 55 million years ago. That’s when snakes were beginning to evolve into their present forms.
The snake fossil, embedded in limestone, undergoes a C-T scan
“Snakes are legless lizards, they are simply lizards that lost, have lost their legs during the evolution of the group.”
That’s Hussam Zaher, a snake specialist who came from Brazil to examine the fossil. Zaher wanted to know if Clarice still had signs of remnants legs, called vestiges.
“The CT scan helped us to answer that question very clearly, and it doesn’t. It doesn’t have any hind limb vestiges, which is kind of unexpected.”
Zaher was surprised because other snakes from the Eocene still have vestiges. And yet the C-T scan showed that this fossil does have a primitive skull shape common to snakes from that era.
Bob Bakker is curator of paleontology at the museum. He calls the mixture of features in Clarice an ‘evolutionary mosaic.’ It could lead to an adjustment in our understanding of how and when snakes evolved. Bakker says that after dinosaurs died out 65 million years ago, snakes had a burst of development, along with mammals.
Hussam Zaher, a herpetologist and paleontologist in Sao Paulo, Brazil, came to Houston to conduct the C-T scan and study this rare fossilized snake.
“Furry mammals start taking over and evolving in various directions, and some of them are rodents and if you have rodents you want something to eat them and the best way to eat a rodent is a snake. Snake evolution starts picking up at around 50-55 million years ago but it’s just beginning, there are only a few kinds, you get the explosion of snakes at around 35 million and then you get dozens of species groups. So Clarice is just at the basic branching that will eventually lead to all the modern snakes.”
Clarice is the only known fossil of a snake that is completely intact. But instead of chipping away the rock from the fossil, which could damage it, the paleontologists will use the C-T imagery to study Clarice and build a replica. Eventually, Clarice will be one of the main attractions in a new exhibit.
“The Houston Museum in two years will open a fabulous new fossil hall. Dinosaurs, of course, and saber-toothed cats, and mastodons and mammoths and trilobites, wonderful trilobites, but we really wanted a snake, because snakes are among the most mysterious and elegant creatures ever to have evolved. Snake fossils are rare. Beautiful ones are rarer still.”
C-T scan reveals a digital view of the fossil