About 110 million years ago, along the shores of an ancient lagoon in what is now northeastern Brazil, a two-legged Cretaceous dinosaur of chicken size made its life hunting insects and perhaps small vertebrates, such as frogs and lizards.
Inside, it was common, with a skeleton similar to many small dinosaurs from the previous Jurassic period, scientists said on Tuesday. Outside, it was anything but.
This dinosaur, called Ubirajara jubatus, has a mane of hair-like structures, while boasting two completely unique, rigid, ribbon-like features, probably made of keratin – the same substance that forms hair and nails – that comes out of the shoulders.
“There are a lot of other strange dinosaurs, but this one is different from any of them,” said paleobiology professor David Martill of the University of Portsmouth in England, who helped lead the study published in the journal Cretaceous Research.
Ubirajara hair-like structures appear to be a rudimentary form of feathers called protopenes. It was not a hair in itself, a feature exclusively of a mammal. Many dinosaurs had feathers. In fact, birds evolved from small-feathered dinosaurs about 150 million years ago.
“It probably looked hairy rather than feathery from a distance,” Martill said. “He probably had hair-like protophenes on a large part of his body, but they are kept only along his neck, back and arms. The ones on his back are very long and give him a kind of mane that is unique to dinosaurs.”
Ubirajara’s ribbon-like structures could have been used for display, possibly to attract colleagues or intimidate opponents or compete with men, Martill added. Such displays are often made by male animals – think of the elaborate tail feathers of a peacock – leading Martill to make a “polite assumption” that this Ubirajara individual was a man.
“The ribbons that seem to come from the shoulders are nothing like anything I’ve seen in nature,” Martill said.
Although it is impossible to know from the fossil, Martill said that Ubirajara could have been colored.
“I bet it was,” he added.