Paleontologists from the University of Colorado Denver found 60 or so furrows scraped into sediment laid down around 100 million years ago at several sites in Colorado. They believe the furrows, distinguished by claw marks with a central hump of earth between them, are evidence of mating rituals performed by Acrocanthosaurus, a large, predatory bipedal dinosaur.

Similar behavior can be found in modern ground-dwelling birds, who scrape the dirt as they twist and kick to show off their strength and nest-building capabilities when it’s time to mate.