An international team has discovered among the fossils in the collection of the State Museum of Natural History in Karlsruhe, Germany, a dinosaur unlike any other known. Although it had gone unnoticed by scientists until now, in life, this creature was not exactly invisible. The dinosaur, the size of a modern chicken, walked around what is now Brazil 110 million years ago looking as fabulous as you can imagine. A long mop of hair ran down its back to its legs and, what is more enigmatic, long, rigid keratin ribbons projected outwards and backwards from its shoulders.
Paleontologists, who have never seen anything like it, believe that the animal used these extravagant attributes to dazzle potential mates or intimidate peddlers or competitors. The finding, published in the journal Cretaceous Research, may shed light on how peacocks and other birds inherited their ability to show off.
The specimen was recovered from the two stone slabs it was on. Using X-rays, the researchers found previously hidden skeletal elements and soft tissues, allowing them to build a clear picture of their features. They named the new species Ubirajara jubatus, a Tupi Indian name for "Lord of the Spear," in reference precisely to the creature's elongated, flat, rigid structures, each with a small sharp crest in the middle. These tapes were placed so as not to impede freedom of movement in the arms and legs, so they would not have disturbed the animal when hunting, grooming or sending signals.
a young male
The ribbons "were probably used for display, attracting mates, competing between males or scaring off enemies," says David Martill, co-author of the study at the University of Portsmouth. The researchers cannot prove the sex of the specimen, but believe it was likely a young male, "which is surprising given that the most complex display skills are reserved for mature adult males," Martill adds. Furthermore, given its extravagance, it is not difficult to imagine that the dinosaur would have indulged in an elaborate dance to show off its striking appearance.
The ribbons, explains Robert Smyth, also from Portsmouth, are not scales or skin, nor are they feathers in the modern sense. They appear to be structures exclusive to this animal. "We would never have predicted these rare features in such a small animal if we had only had the skeleton preserved," he admits.
Standing hair
A section of the long, thick hair that runs down the animal's back was almost intact. The legs were also covered with fur-like filaments. It is believed that this hair was controlled by muscles that allowed it to rise, similar to a dog raising its hair on end or a porcupine raising its spines when threatened. In this way, Ubirajara could flatten his mane close to the skin when he was not displaying himself, which would have allowed him to move quickly without becoming tangled in vegetation. "Any creature with mobile hair or feathers as body coverage has a great advantage in making the contour of the body more aerodynamic to hunt or escape faster, but also to capture or release heat," says Martill.
But why adorn yourself in a way that makes you more obvious to both your prey and potential predators? "For many animals, evolutionary success is about more than just surviving, you also have to look good if you want to pass on your genes to the next generation," says Smyth.
A heritage for birds
«Modern birds are famous for their elaborate plumage and displays that they use to attract mates; the tail of male peacocks and birds of paradise are clear examples. "Ubirajara shows us that this tendency to show off is not a unique characteristic of birds, but something that birds inherited from their dinosaur ancestors," he adds.
Smyth argues that Ubirajara's plumage could have improved the chances of survival for a small animal like it. Many dinosaurs had bony crests and frills, which they probably also used for display. But bone requires a lot of energy to form and maintain. Additionally, it is heavy and can cause serious injury if it breaks. However, "keratin, the material that makes up hair, feathers and scales, is a much less expensive display alternative for the body to produce, it is also lightweight, flexible and can be replaced regularly if damaged." Much more effective for an animal no larger than a chicken.