Dinosaurs Danced in Bird-Like Mating Rituals

Dinosaurs not only danced, but they also did so with such enthusiasm that they left behind fossilized footprints as evidence of their moves, a new paper by an international team of paleontologists reports.

The discovery confirms prior speculation, based on dinosaur head crests and colorful feathers, that some dinosaurs engaged in mating displays that were similar to those of modern birds. The dancing dinos, according to the paper published in the journal Scientific Reports, were likely large theropods, meaning two-legged carnivorous dinosaurs.

“They were evidently very active and perhaps driven into frenzies by the excitement of the breeding season,” project leader Martin Lockley of the University of Colorado Denver, told Discovery News.

“This is typical of some bird species,” he continued. “The extensive scrape evidence suggests much high-energy activity. If small birds get excited when breeding, imagine what big theropods might have done!”

Lockley and his team found the fossilized dinosaur scrape marks in 100-million-year-old Dakota sandstone in western Colorado. Since the footprints could not be removed from the rocks without causing damage, the scientists recreated them in virtual 3-D, using a technique of layering photographs known as photogrammetry. Rubber molds and fiberglass copies of the footprints were also made and are now stored at the Denver Museum of Nature & Science.

Various interpretations of the fossilized footprints were considered, such as whether or not dinosaurs made them while digging for food or marking territory. These were all discounted for multiple reasons, with only mating dance behavior providing the best explanation for the ancient prints. In fact, the marks closely match those created by dancing birds today, such as Atlantic puffins and ostriches.

The time and location of the prints indicate that they were made by Acrocanthosaurus, a dinosaur that grew close to 38 feet in length and weighed up to 6.8 short tons. Its rhythmic stomps and scratches, comprising what the researchers call a "scrape ceremony," must have reverberated for quite a distance. The dinosaur probably vocalized as it performed the ritualistic scraping and bobbing movements, as today’s birds do.

The scientists also suspect that males of this and certain other carnivorous dinosaur species were the primary dancers.

“Males are the main show offs, at least in birds today,” Lockley explained. “This seems to be a hormone- and instinct-driven behavior of the breeding season to attract and pair with a mate.”

Males probably then competed during the spring breeding season while females looked on. The dancing displays likely occurred in assembly areas known as leks.

The behavior might date to long before the Cretaceous, but that remains unclear for now. Carnivorous dinosaurs were among the most active of all dinos, helping to explain why they were the dancers. It is doubtful that large, lumbering herbivores, such as sauropods, moved much for mating rituals, much less for other activities.

It is probable that some carnivorous dinosaurs gave rise to bird descendants that retained the display abilities, but Lockley said that “there is no reason to suppose that all theropods developed this behavior, or that all descendants should have inherited it.”

Read more at Discovery News