Around 100 million years ago, on a tidal flat near what is now Denver in the US state of Colorado,dinosaurs may have gathered to dance. According to anew study published inCretaceous Research, new findings suggest that dozens of mysterious scrape marks preserved in stone at Colorado’s famed Dinosaur Ridge represent one of the largest known dinosaur mating display arenas – known as leks – ever discovered.

“Leks – or ‘courtship arenas’ – are areas where a number of individuals congregate to participate in courtship display behaviours to attract potential mates,”Dr Caldwell Buntin, lead author of the study, toldBBC Science Focus.

Many modern birds (the descendants of dinosaurs) including knots and plovers exhibit such behaviours, Buntin said.

The idea that dinosaurs performed such rituals was first proposed by palaeontologistDr Martin Lockley, who noted similar traces nearby. This new study significantly expands on that evidence, revealing more than 30 distinct scrape marks across multiple layers of sediment.

The traces fall into two categories: broad, shallow bowl-like marks and narrower, overlapping scrapes. Many appear to have been made by backwards kicking movements from both feet, sometimes while rotating.

Drone imagery from a 2019 US Geological Survey and follow-up surveys in 2024 helped the team map the site in detail, as walking on the site is prohibited.

“This was a one-of-a-kind find,” said Buntin, who worked with Lockley until his death in 2023.

“We were extremely excited, and it was a surreal moment looking at the drone imagery for the first time and noticing scrapes pop up all across the screen. It was definitely a ‘eureka!’ moment for me.”

The exact species responsible for the markings remains unknown, but based on nearby fossil footprints Buntin pointed toAcrocanthosaurus – aT. rex–like predator – and ostrich-likeOrnithomimids as likely candidates.

He said it’s unlikely thatT. rexitself engaged in similar courtship displays, as “this behaviour seems to have required complex social relationships and was probably associated with herding or travelling in groups.”

Buntin now hopes to revisit other potential lek sites across western Colorado to reassess earlier interpretations of the scrapes there.

If confirmed, these scrapes would offer one of the clearest windows yet into the reproductive lives of dinosaurs – revealing not just how they reproduced, but how they courted and competed for mates.

Read more:

• 7 dinosaurs we've all been getting completely wrong
• How did dinosaurs mate?
• The mystery of this 10,000-dinosaur graveyard may have just been solved

About our expert

Rogers 'Caldwell' Buntin is a graduate teaching assistant at Old Dominion University. His research has been published in journals includingSedimentary Geology andCretaceous Research.