April 3, 2015
‘Romeo & Juliet’ dinos fossilized while mating
"Romeo and Juliet with dinosaurs" might sound like a sequel to Pride and Prejudice and Zombies, but in reality, it’s the phrase being used to describe a recently-discovered ancient couple found buried beneath a collapsed sand dune in Mongolia’s Gobi Desert.Discovered by University of Alberta paleontologist Scott Persons and his colleagues, the dino duo were named in honor of Shakespeare’s famous ill-fated lovers because they were apparently enjoying a romantic encounter when they were entombed for more than 75 million years.
Telling male dinosaurs from female ones? Harder than you’d think.
In a statement, Persons, a graduate student and the lead author of a new Scientific Reports paper describing the find, explained that determining the gender of the dinosaurs was the tricky part. It is “really hard” to do so, he explained. “Because soft anatomy seldom fossilizes, a dinosaur fossil usually provides no direct evidence of whether it was a male or a female.”
He and his fellow researchers instead compared the remains of the oviraptors (bird-like dinosaurs that had two legs) with the anatomy of modern avian species, Discovery News said. They found evidence that the creatures had long feathers on the end of their tails. The oviraptors were unable to fly, however, which means that the tail feathers had to serve another purpose.
“Our theory was that these large feather-fans were used for the same purpose as the feather fans of many modern ground birds, like turkeys, peacocks, and prairie chickens: They were used to enhance courtship displays,” Persons said, adding that an analysis of the tail skeletons revealed “adaptations for both high tail flexibility and enlarged tail musculature – both traits that would have helped an oviraptor to flaunt its tail fan in a mating dance.”
Evidence of sexual dimorphism discovered
Building upon those findings, Persons and his colleagues analyzed the tailbones of each of the newly found dinosaurs, and found that one had larger, specially shaped tailbones, an indication that it would have been used for elaborate courtship displays.
“We discovered that, although both oviraptors were roughly the same size, the same age, and otherwise identical in all anatomical regards, 'Romeo' had larger and specially shaped tail bones,” indicating that it was most likely the male, the author explained. By comparison, Juliet had shorter, simpler tail bones less suitable for “peacocking” and was probably female.
Persons went on to suggest that that there was a good chance that the duo was a mated pair that was ultimately trapped and preserved for more than 75 million years by the collapsed sand dune that did them in. Which is sort of romantic, in a Shakespearean kind of way.