MORRISON, Colo. (CBS4) – Lines in the sandstone at Dinosaur Ridge in Morrison have uncovered more mysteries about dinosaurs, particularly how they mate.

It now seems likely those scratches, from more than 100 million years ago, were made by a predecessor to the Tyrannosaurus rex during a mating ritual.

“It’s a kind of dinosaur foreplay,” said Professor Martin Lockley at the University of Colorado Denver, who made the discovery. “And it’s very frenzied. It’s a very repetitive activity.”

Lockley says that ritual is reminiscent of birds.

“And it’s known from the study of modern birds, that scratch the ground to build nests, that they may make a dozen or even 100 scratches before they finally decide on the best nest site,” he said.

Professor Martin Lockley (credit: CBS)

Professor Martin Lockley (credit: CBS)

The discovery is the first of its kind across the world, and similar scratches were also discovered in Gunnison. Lockley says he and a colleague arrived at the conclusion the marks were indicative of mating through a process of elimination.

Cameron Binkley, a Californian who grew up in Morrison, was visiting Dinosaur Ridge on Thursday and told CBS4 the news of the discovery is exciting.

LINK: DinoRidge.org

“This is great, that they have continued to find new stuff here in these rocks to reinterpret, or help us interpret dinosaurs,” Binkley said.