Science on Tap: Michelle Stocker and the Mystery of the Missing Femur

Michelle Stocker (and audience members) dressed up for the Science on Tap costume contest.

Paleontologists are fundamentally detectives, says Virginia Tech paleontologist  Dr. Michelle Stocker. They investigate what has happened on Earth through the clues that have been left behind. One common mystery they solve is “Who killed whom?”

Sitting in a cabinet in California was a 216-million-year-old femur without an identity. And Stocker wanted to ID the bone and uncover its story.

Speaking at Rising Silo Brewery at a Science on Tap event November 1, Stocker said that finding out “when and where [the fossil] is found is just as important as the bone itself.” Stocker analyzed the fossilized femur and discovered that it was from Ghost Ranch, New Mexico. Although the location is often associated with artist Georgia O’Keeffe, it is also a famous location in the world of paleontology. The location is the site of the discovery of hundreds of early dinosaurs, most notably the Coelophysis.

However, this femur didn’t belong to a Coelophysis. Upon further inspection, Stocker and her team found that the femur belonged to a Rauisuchid, which is extinct and not a dinosaur. Stocker explained to her Science on Tap audience, “Not all fossils are dinosaurs.” This is a common misconception propagated by movies such as the “Jurassic Park” series.

Stocker also noticed that there were holes in the bone. Markings such as these can provide evidence about the animal’s behavior and environment. As the research team looked more closely, they dove deeper into the mystery.

The next question for Stocker was, “Who or what bit the Rauisuchid?” To answer this question, the paleontology team decided to take a CT scan of the bone. They were ecstatic to find that they had found a possible murder weapon–a tooth. Using the scan, the scientists were able to create a 3D print of the tooth to help them find its original owner.

The tooth, Stocker told the Science on Tap audience, once belonged to a powerful Phytosaur. Phytosaurs were dominant in water and were like great, big crocodiles. Rauisuchids, on the other hand, are known to have lived on land. With this information, the scientists were led to believe that the Rauisuchid and the Phytosaur must have gotten into a scuffle outside of their respective environments.

But the Phytosaur wasn’t the murderer. Because the tooth was surrounded by healed bone and the location of the bite mark was on a meaty part of the Rauisuchid, the paleontologists concluded that these markings were the result of a painful, but not fatal, battle.

The scientists are not yet finished asking questions about this fossil. Now they’re wondering, “Well, how hard did the Phytosaur have to bite to make these marks?” Stocker and her team are currently using nickel casts to crush cow bones to measure the force that is necessary to bite the bone that hard.

What started out as a bone with no home and no history now has an intricate story woven from events that happened a long, long time ago.

Sponsored by the Center for Communicating Science, Science on Tap is a New River Valley project that brings research to the public.

By Kendall Daniels, Center for Communicating Science student intern

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