In a quest to learn how two-legged dinosaurs moved, scientists watched their descendants — birds — run around on a race track. After all, chickens were once carnivorous dinosaurs that stalked the Earth on giant drumsticks.

For all the movies that show dinosaurs chasing after humans, we don’t actually know much about what a walking or running dinosaur looked like. Footprints and fossils, for example, can’t tell us whether a dino strode or strutted. “They’re static records of an animal or its movement,” says Peter Bishop, a scientist at the Queensland Museum. For movement, he says, “That’s when you’ve got to study animals that are living today.”

Only, there aren’t any dinosaurs wandering around anymore. So Bishop and his colleagues turned to the next best thing: birds, the only surviving descendants of two-legged dinos called theropods. Bishop and his colleagues rounded up a dozen species from cute little quail and turkeys to long-legged ostriches and emus. Then they sent the birds walking and running down a racetrack.

The researchers filmed the birds with a two-camera setup kind of similar to the motion-capture technology used for movies. They recorded 3D measurements like how high the birds’ hips moved during each stride, and reported them Wednesday in the journal PLOS ONE. The tracks were also outfitted with special platforms, so the team could measure the force of their steps.

These measurements helped the research team develop models that use the bird’s size and speed to predict key aspects of its movement — like stride length and general bounciness. They found that body size has a big influence on how birds — and, probably, their dinosaur ancestors — moved, Bishop says. Smaller birds scurry in more of a crouched position, and bigger birds’ legs stretch out to create a more upright pose.

The eventual aim is to use these equations on dinosaurs, too — but they’re still a work in progress. So Bishop hasn’t received any phone calls from Steven Spielberg yet, he says. “But I’m waiting by the phone.”

Bishop speculates that a T. rex probably wasn’t a very graceful runner. “Like a big turkey or ostrich, just moving with a lot more effort,” Bishop says. “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 lumbering turkey with teeth doesn’t make it any less terrifying.

https://www.theverge.com/2018/2/24/17046554/birds-track-non-avian-theropods-locomotion-dinosaurs-running