Flamboyance in the age of dinosaurs

Scientists suggest this is the most elaborately dressed-to-impress dinosaur ever described.

Ubirajara jubatus was small, about the size of a chicken, but had a prominent mane of long fur down its back and stiff ribbons projecting from its shoulders – features never been seen in the fossil record.

Its flamboyance was likely used to dazzle mates or intimidate foe, the researchers say, and sheds new light on how birds such as peacocks inherited their ability to show off.

The first non-avian dinosaur described from Brazil’s Crato Formation, a shallow inland sea laid down about 110 million years ago, it is also the first from the ancient supercontinent of Gondwana with preserved skin.

It was actually found among fossils in Germany’s State Museum of Natural History Karlsruhe by a team led by the museum’s Dino Frey and by David Martill and Robert Smyth from University of Portsmouth in the UK.

Frey excavated it from the two slabs of stone in which it lay and, using x-ray, found previously hidden skeletal elements and soft tissue.

The fossil is likely of a young male. It lived 110 million years ago during the Aptian stage of the Cretaceous period and is closely related to the European Jurassic dinosaur Compsognathus.

Its ribbons are not scales, fur or feathers in the modern sense; rather, they appear to be structures unique to this animal.

“These are such extravagant features for such a small animal and not at all what we would predict if we only had the skeleton preserved,” says Smyth. “Why adorn yourself in a way that makes you more obvious to both your prey and to potential predators?

“The truth is that for many animals, evolutionary success is about more than just surviving, you also have to look good if you want to pass your genes on to the next generation.”

The mane is thought to have been controlled by muscles that allowed it to be raised, in a similar way that a dog raises its hackles or a porcupine raises its spines when threatened. It could be lowered when not in a display mode for faster movement.

The long, flat, stiff shoulder ribbons of keratin, each with a small sharp ridge running along the middle, were positioned to not impede freedom of movement in its arms and legs, so wouldn’t have limited the animal’s ability to hunt, preen and send signals.

Smyth argues that the elaborate plumage might have improved its chances of survival.

“Ubirajara is the most primitive known dinosaur to possess integumentary display structures,” he says. “It represents a revolution in dinosaur communication, the effects of which we can still see today in living birds.”

The name comes from a Tupi Indian word for “lord of the spear” and jubatus, from the Latin, meaning maned or crested.

The study is published in the journal Cretaceous Research.