Narrator: This is Science Today. What were flying dinosaurs like? Paleontologist Kevin Padian of the University of California, Berkeley analyzed a 100 million year-old deposit of pterosaur bones found in a desert in Chile. Under the microscope, the bones were of young, fast-growing animals.

Padian: So we thought maybe this was a rookery. Maybe it was a colony of breeding pterosaurs that were out there on a plain.

Narrator: Some scientists have speculated that pterosaurs were slow-moving and crawled around on all fours when they weren't flying, sort of like bats. Padian says that isn't so. These animals lived on a treeless desert.

Padian: Let's look at this situation we have here in Chile. We have all these pterosaurs sitting out here on a plain. There's no trees, there's no cliffs, they're not going to be hanging upside down, they're not going to be in a bat-like pose, they're not going to be roosting in trees. They're apparently roosting on open ground.

Narrator: Exactly, says Padian, like modern day gulls and other sea birds.

Padian: This was more in tune with the reconstruction of pterosaurs that has them as upright animals that are warm-blooded, quite active and that cared for the young until they were old enough to fly away.

Narrator: For Science Today, I'm Steve Tokar.