Clarification appended.
A plump guinea fowl walks across a bird-sized treadmill. X-rays record the precise movement of the bird's bones, tracking its hips as they interact with its legs. A computerized model of the bones is aligned with x-ray images, and an animated bird skeleton begins to walk on screen.
In another of the lab's projects, bird feet are dipped into trays of mud, leaving three-pronged tracks in the goop.
Professor of Biology Stephen Gatesy is using these birds and their footprints to study dinosaur movement. By collecting data on living animals, he is able to draw conclusions that can be applied to the study of fossils.
Birds are the best living model organism when it comes to deciphering fossils and dinosaur movement, Gatesy said. "You see fossils with a different set of eyes each time you learn something new about a living animal."
He is interested in using his guinea fowl models to study how the skeleton moves. One major question he seeks to answer is why joints move as they do, and not in certain angles and directions, he said.
The group has also conducted similar experiments to study bird flight.
But Gatesy, who has taught anatomy courses to medical students, likes to focus on the minute and subtle behavior of the bones. "Each joint has a different solution to movement," Gatesy said. Studying locomotion can help describe how, for instance, a knee joint is different from an ankle joint. "I'm an anatomist," he said. "I love the shape of things and the structure."
Robert Kambic GS works in Gatesy's lab and shares his interest in "dino" movement. Wearing a dinosaur-themed T-shirt, he pulled up images of bird bones on the computer screen. He studies the "types of ligaments and soft tissues you put in a joint to get certain movement" and said he hopes to "see if there are broad rules that we can apply to the dinosaurs as well."
Gatesy called his work "exploratory," emphasizing that it is more discovery-based than hypothesis-driven.
Footprints left in Gatesy's trays of mud reveal a surprising level of detail. He uses the prints to create three-dimensional animations of footprint formation.
"How does the foot interact with the mud?" he asks. A footprint does not represent a single moment in time. Instead, each subtle movement of the foot — as it sinks millimeter by millimeter through the mud — results in slight disturbances in the medium.
Gatesy mixes beads into mud before sticking a bird's foot — or model of a bird's foot — into the mixture. Using x-ray data and computer animation, he is able to track the movement of individual beads as the foot sinks in.
Now, researchers are able to apply this knowledge of footprint formation to trace fossils around the world. Looking at a footprint, a paleontologist can make a more informed analysis of the dinosaur's movement — based on evidence, thanks to Gatesy's guinea fowl.
A previous version of this article stated "the lab snips certain ligament or connective tissue, looking at ways the animals' movement responds." Such procedures are only performed on cadavers.
