Many modern birds perform intricate dance routines to woo their partners, a practice that their ancient ancestors – dinosaurs – may have invented. Fossilized foot scrapes etched into outcrops in Colorado indicate large male theropods likely had dance competitions to impress the ladies.

An international team of paleontologists, led by Martin Lockley of the University of Colorado, Denver, discovered large scrape marks across four sites in Colorado, three in the western part of the state and one in the east, within sediments from the Cretaceous period, between 145 million and 66 million years ago.

"These are the first sites with evidence of dinosaur mating display rituals ever discovered, and the first physical evidence of courtship behavior," Lockley said in a statement. "These huge scrape displays fill in a missing gap in our understanding of dinosaur behavior."

Theropods were large two-legged carnivorous dinosaurs, equipped with three-toed feet. Some of the grooves left behind measured up to six feet-long and a foot wide, while others were much smaller. Based on the date and location of the scrape marks, researchers believe they were made by Acrocanthosaurus, a 110 million-year-old dinosaur that grew close to 38 feet in length and weighed up to 6.8 tons.

Similar mating behavior is common in modern mammals and birds. Until now, however, scientists could only speculate about dinosaur mating behavior, although it was assumed to be similar to that of their modern relatives, birds.

"The scrape evidence has significant implications," Lockley added. "This is physical evidence of prehistoric foreplay that is very similar to birds today. Modern birds using scrape ceremony courtship usually do so near their final nesting sites. So the fossil scrape evidence offers a tantalizing clue that dinosaurs in 'heat' may have gathered here millions of years ago to breed and then nest nearby."

The study was recently published in the journal Scientific Reports

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