In a search to learn how two-legged dinosaurs moved, scientists watched their descendants, the birds, run on a racetrack. After all, chickens were once carnivorous dinosaurs that lurked the Earth in giant drumsticks.
For all the movies that show dinosaurs chasing humans, we do not really know much about what a walking or running dinosaur was like. Footprints and fossils, for example, can not tell us if a dino walked or strutted. "They are static records of an animal or its movement," says Peter Bishop, a scientist at the Queensland Museum. For the movement, he says: "That's when you have to study the animals that live today."
Only that there are no longer dinosaurs wandering around. So Bishop and his colleagues turned to the next best option: the birds, the only surviving descendants of two-legged dinos called theropods. Bishop and his colleagues gathered a dozen species, from quail and cute turkeys to long-legged ostriches and emus. Then they sent the birds to walk and run along a racetrack.
Video: Peter Bishop / Queensland Museum and Christofer Clemente / University of the Sunshine Coast
The researchers filmed the birds with a two-camera configuration similar to the motion capture technology used for movies. They recorded measurements in 3D, such as how tall the hips of the birds moved during each stride, and reported them on Wednesday in the journal PLOS ONE. The tracks were also equipped with special platforms, so the team could measure the strength of their steps.
These measures helped the research team to develop models that use the size and speed of the bird to predict the key aspects of its movement, such as the length of the stride and the general bounce. They discovered that body size has a great influence on how birds moved – and, probably, their ancestors of dinosaurs – says Bishop. Smaller birds scurry in a crouched position, and the legs of larger birds extend to create a more upright posture.
The ultimate goal is to use these equations in dinosaurs as well, but they are still in progress. So Bishop has not received any phone calls from Steven Spielberg yet, he says. "But I'm waiting for the phone."
Bishop speculates that a T. rex was probably not a very elegant runner. "Like a big turkey or an ostrich, it just moves with a lot more effort," says Bishop. "At the end of the day, he's trying to move basically the size of an elephant on two legs instead of four." Somehow, imagining a T. rex as a heavy turkey with teeth does not make it any less terrifying.