From peacocks to birds of paradise – some of today’s bird species are known to be extremely splendid. A fossil with traces of bizarre decorative elements makes it clear that this tradition goes back to the age of the dinosaurs. The biped, about the size of a chicken, had pairs of stiff bands made of keratin that protruded from the shoulders and a kind of mane made of feather structures that it could probably puff up. Paleontologists say that these elements were probably used in courtship or to deter enemies.
Once they were depicted naked and colorless – but studies of numerous fossils have now shown that many types of dinosaurs were also lavishly “dressed”: They wore feathers or fur-like structures with complex colors and drawings – similar to their descendants, today’s birds. Species have also been described whose plumage characteristics suggest that they displayed it to impress other species. However, the newly discovered dinosaur is now the most bizarre example of such a “primeval show star”, reports the international team of palaeontologists.
The fossil came from a site in the Crato Formation in northeastern Brazil and was dated to an age of 110 million years. It is believed that there was a shallow inland sea with islands in the Cretaceous Period. The results of the investigation on the fossil embedded in two stone slabs were made possible through the use of modern analysis technology: Co-author Eberhard Frey from the State Museum of Natural History in Karlsruhe x-rayed it to make hidden fine structures visible. In addition to some hidden skeletal parts, traces of the former appendages and the skin structures of the chicken-sized dinosaur were also visible.
Strange bands on the shoulders
“The most amazing feature of this animal was the long, probably stiff, ligament on either side of its shoulders,” says University of Portsmouth co-author David Martill. These elements, never previously described in a fossil, appear to have been positioned so that they did not restrict the freedom of movement of the arms and legs. Similar structures are known today from the banded bird of paradise (Semioptera wallacii). According to the research, the shoulder straps on the dinosaur were also made of keratin, but they were not feathers in the modern sense.
Presumably these conspicuous structures served, similar to the parrot birds, to attract partners or to compete between males. But it also seems possible to have a function to deter enemies, say the researchers. The ribbons were probably presented in connection with another element that they found on the fossil: the animal had a kind of mane made of long fur-like feather structures on its back. The arms were also covered with fur-like threads down to the hands. The paleontologists suspect that the dinosaur was able to erect its mane by muscles, similar to some modern animals, in order to fluff itself up impressively.
Probably a splendid male
Given its features, scientists gave the dinosaur the name Ubirajara jubatus. The first part means “lord of the spear” – alluding to the presumably stiff ligaments and jubatus means “maned”. “We cannot prove that the specimen was male, but given the differences between male and female birds today, this seems very likely,” says Martill. “Its extravagance also suggests that the dinosaur performed elaborate dances in order to present its splendor in a particularly impressive way,” says the scientist.
His colleague Robert Smyth adds: “It is known that many dinosaurs had combs, spines and other bony structures that were probably also used for display. In birds, however, the corresponding elements consist of feathers. This little dinosaur is now an early example of this arguably sensible concept. Because bones require a lot of energy to grow and be maintained, they are also heavy and can cause injuries if they break, ”says Smyth. “Keratin – the material that makes hair, feathers and scales – is a much better material for a show element – especially on an animal as small as this,” explains Smyth.
He concludes: “Some of our modern birds are famous for their intricate plumage and the way they display their mate – the peacock wheel and the plumage of the male birds of paradise are textbook examples of this. Ubirajara makes it clear, however, that this tendency to display was not a new development of birds, but something that these animals inherited from their dinosaur ancestors, ”the paleontologist sums up.
Source: University of Portsmouth, Article: Cretaceous Research, doi: 10.1016 / j.cretres.2020.104686