It must have been an amazing sight: Paleontologists now say that dinosaurs danced—with gusto. More specifically, they think that some male dinosaurs did so as part of a mating display to woo females, study authors say in a post at Phys.org. The evidence? Telltale scrape marks from claws etched into 100-milliion-year-old sandstone in Colorado, reports Discovery. Some were more than 6 feet long, and researchers at the University of Colorado Denver ran through several possible explanations. Digging for water? Nope, it was plentiful in the area back then. Digging for food? Nope, these were meat-eating theropods not interested in roots. And then the scientists zeroed in on the similarity to a mating ritual of modern birds known as "nest scrape display," reports Live Science.
"During the breeding season, the males start to get excited and show off to their mates by scratching to say, Look, I can build a nest!" says co-author Martin Lockley. "And they get so excited that they scratch, and move along and scratch again—they make dozens or hundreds of scratches in a short period of time." Lockley's team realized the scratch marks they were seeing at sites well-traveled by dinosaurs bore these hallmarks. A paleontologist not involved with the study tells the Christian Science Monitor that the theory makes sense. "Considering that modern birds are descended from Mesozoic theropod dinosaurs, it shouldn't be surprising that birds' ancient relatives would have done this, too." (One of the biggest raptors ever was just found in the US.)