It is quite possibly every paleontologist's dream to discover a dinosaur completely unknown to science. So imagine the shock and excitement of paleontologist David Martill and his team when they came upon a tiny dinosaur with the power to shake up the fossil record and reshape our understanding of these ancient creatures.
In research published Monday in Cretaceous Research, Martill and his colleagues unveiled their groundbreaking discovery of a late Cretaceous-era dinosaur they have dubbed Ubirajara jubatus — a small creature which had some pretty unusual features.
What they discovered — The researchers classified the new dinosaur as a 'compsognathid' theropod — one of a kind of small, bird-like dinosaurs. Theropods themselves are a diverse group of dinosaurs which also included the terrifying Tyrannosaurus rex — it is these dinosaurs that modern-day birds are thought to be descended from.
The species described in this study breaks new ground in two key ways.
First, it's the only known non-avian dinosaur to have ever been found in the Crato Formation, an area of northeast Brazil — also known as Gondwana — which may yield rich opportunities for further dino discoveries. Most other non-avian theropod fossils of this kind have previously been found in China or Germany.
According to the study, the discovery of Ubirajara jubatus in this area "shows the potential of the Crato Formation as a crucial location for obtaining a greater understanding of feathered dinosaurs and their evolution."
Second, the dinosaur displays some unusual characteristics never seen before on any other non-avian theropod. Known as "integumentary features," these physical features may have been important in maintaining body temperature, egg incubation, and sexual display.
Digging into the details — The most impressive of the Ubirajara jubatus' features are elongated, ribbon-like structures protruding from the base of their necks — also known as "proto-feathers."
To add to the feather-like structures, these theropods also have slender filaments stemming from the base of their necks and cascading down their dorsal regions. Together, these features form an impressive mane.
Although other dinosaurs display similar elongated "proto-feathers," only theropods belonging to the Maniraptoriform group are recorded as having such protrusions. No other non-avian theropods have ever been found to possess these proto-feathers — until Ubirajara jubatus.
"The new fossil is exciting in so many ways. It shows that some of the more basal theropods which did not have proper feathers, but 'proto' feather-like structures were already co-opting them for sexual display and behavioral uses," Martill, a co-author on the study and professor of paleobiology at University of Portsmouth, tells Inverse.
As the study states: "These structures do not correspond to any possible impression made by a bony element that we would expect to find associated with an animal of this kind."
Why it's newsworthy — The new creature's name means "lord of the feather" in Tupi Indian. It is an appropriate title for reason beyond the physical features — Ubirajara jubatus prompts a retelling of the evolution of feathered creatures, including modern-day birds.
Researchers speculate the dinosaur used its proto-feathers not for flight, but for sexual displays when courting a mate.
"It shows that elaborate behavior in these dinosaurs was already occurring before true feathers had evolved," Martill says.
A few modern birds have similar elongations on their bodies, which they use during mating displays, too.
"A few birds have brightly colored shoulder feathers, and a few birds of paradise have elongated feathers used in displays located near the shoulders," Martill says.
But most modern birds tend to display feathers on their tails rather than on the shoulders.
"Mostly, birds tend to use the tail feathers, which can impede flight, so there is a trade-off there," Martill says. "And they develop crests on the top of their heads — cockatoos famously," he adds.
Ultimately, non-avian theropods tend to possess integumentary features that modern creatures largely lack. The disappearance of such prominent characteristics is a strange casualty of evolution.
As the study states: "We might expect to find a range of integumentary display structures in non-paravian theropods that are without modern analogues."
Martill adds: "The structures seen in this new dinosaur are rare in modern animals."
What's next — This dinosaur represents a step forward in reconstructing the complex history of theropods and how they evolved. It also confirms the suspicions of the paleontology community, Martill says.
"It is great that a theropod with proto-feathers has now turned up in Gondwana, but I think we already know they were there; we simply had not been lucky enough to find them until now," Martill says.
Perhaps now we have found this species, more will come to light.
Abstract: Discoveries of dinosaurs with integumentary structures over the last few decades have revolutionised our understanding of the phylogenetic relationships between birds and dinosaurs as well as the origin and evolution of feathers. A remarkable number of dinosaurs have been discovered with a diverse range of preserved integumentary structures. Several of these dinosaurs are adorned with elaborate integumentary structures that have been linked to behaviours including thermoregulation, egg incubation, and sexual display. Among Theropoda, such elaborate structures have only been previously recorded within Maniraptoriformes. However, elaborate monofilamentous structures are also present in some small ornithischians.The majority of theropods preserving integumental structures come from the Upper Jurassic and Lower Cretaceous of China or the Upper Jurassic of southern Germany, and all are of Laurasian origin. Herein, we describe a new genus and species of compsognathid theropod from the Lower Cretaceous (Aptian) Crato Formation of Northeast Brazil, representing the first Gondwanan non-avian theropod with preserved filamentous integumentary structures. It is also the first non-maniraptoran possessing elaborate integumentary structures that were most likely used for display. These include slender monofilaments associated with the base of the neck, increasing in length along the dorsal thoracic region where they form an impressive mane, as well as a pair of elongate, ribbon-like structures likely emerging from the shoulder. Such elaborate integumentary structures are hitherto unknown in any other dinosaur, although superficially similar elongate display feathers emerge from the carpal region of the male standard wing bird-of-paradise (Semioptera wallacii).