Researchers say that the newly discovered theropod dinosaur footprints indicate that the dinosaurs indulged in a frenzied Cretaceous courtship dance, Christian Monitor reports.
Scientists say the scratch marks left behind in Colorado could be direct evidence of the animals' mating behavior. The markings could be the traces of a courtship dance, similar to the one employed by ground nesting birds.
The paper was published on Thursday in the journal Scientific Reports.
"We now have proof that carnivorous dinosaurs engaged in extremely active courtship displays," study lead author paleontologist Martin Lockley told The Christian Science Monitor in an interview.
Some of the scratch marks discovered are around six feet long. The most prominent marks are made up of two long parallel furrows with a ridge in the middle, with clear scratch marks appearing across the furrows.
The scrape marks were discovered at four sites in Colorado by a team led by Martin Lockley, a paleontologist at the University of Colorado, Denver. Three of the sites are in western Colorado, and one is in the east of the state.
The largest of the four sites, in western Colorado, features some 60 scrapes on a sandstone surface measuring about 50 meters long and 15 meters wide, according to Sciencemag.
The researchers ruled out the explanations that the dinosaurs could be digging for water, for food or for leaving a scent to mark their territory.
"Could they be digging for water? That seems very unlikely," Lockley said..
"These trace fossils of dinosaurs repeatedly scratching the ground are very likely from courtship behavior," Emory University paleontologist Anthony Martin, who was not involved in the study, told the Monitor in an email.
"Some modern birds do similar scratching when displaying or otherwise trying to attract a mate. Considering that modern birds are descended from Mesozoic theropod dinosaurs, it shouldn't be surprising that birds' ancient relatives would have done this, too."
Peter Falkingham, a paleontologist with Liverpool John Moores University who was not associated with the study, suggested that a direct comparison between the scrapes that modern birds make during mating dances and these dinosaur marks would strengthen the paper.
According to The Guardian, the exact species of dinosaur that may have danced is unknown, but researchers feel that it could be Acrocanthosaurus, a gigantic, ridged-back theropod that lived in the wetlands of western North America in the Cretaceous.
