DENVER (January 7, 2016) Dinosaurs engaged in mating behavior similar to modern birds, leaving the fossil evidence behind in 100 million year old rocks, according to new research by Martin Lockley, professor of geology at the University of Colorado Denver. Lockley, a paleontologist, led an international research team that discovered large 'scrapes' in the prehistoric Dakota sandstone of western Colorado. These ancient scrapes are similar to a behavior known as 'nest scrape display' or 'scrape ceremonies' among modern birds, where males show off their ability to provide by excavating pseudo nests for potential mates.

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

The study will be published in the journal Scientific Reports (Nature Publishing Group) on January 7.

Lockley, a world-renowned expert on dinosaur footprints, found evidence of more than 50 dinosaur scrapes, some as large as bathtubs, in an area where tracks of carnivorous and herbivorous dinosaurs have also been confirmed. The display arenas, also called 'leks' were found in two National Conservation Areas (Dominguez-Escalante and Gunnison Gorge) on property permitted by the Bureau of Land Management near Delta, Colorado. 

Lockley also discovered evidence of mating areas at Dinosaur Ridge, a National Natural Landmark, just west of Denver. 

This new fossil evidence supports theories about the nature of dinosaur mating displays and the evolutionary driver known as `sexual selection.' Since prehistoric times, males looking for mates, have driven off weaker rivals. Females, meanwhile, have chosen the most impressive male performers as consorts.