A little cousin of Tyrannosaurus rex has changed the image we usually have of the great dinosaurs that ran on two legs to hunt their prey. The scaly bodies that films like “Jurassic Park” had been showing are being questioned, since the discovery of new fossils shows that larger dinosaurs could also have their entire body feathered. Yutyrannus huali could be the key to discovering important aspects that have been debated for years by paleontologists.
At 9 meters long and weighing 1,500 kilos, Yutyrannus huali is the largest feathered dinosaur we know of to date . It is a theropod dinosaur, classified within the tyrannosauroid family, large predators that walked on two legs, considered the species that gave rise to modern birds. Therefore, although it is not very technical, it could be said that we are dealing with a giant chicken that would cost us a lot to lock up in a pen.
This species has several characteristics, especially in the skull, of tyrannosauroids, such as its three-fingered hands and the typical foot of theropods. But what makes this specimen a significant find are its filamentous feathers, which provide clear evidence for the presence of feathers in large dinosaurs and, while changing pre-existing conceptions, offer new insights into early evolution. of feathers, a long-standing theme in paleontological studies.
Until the discovery of Yutyrannus , the largest feathered dinosaur was Beipiaosaurus inexpectus , about 2 meters long and weighing about 85 kilos. Therefore, considering the dimensions of Yutyrannus, we are facing a considerable difference between the dinosaurs with larger feathers. Of course, the discovery of this evidence leads us to think about the possibility that other large dinosaurs could wear feathers during their adult stage, a difficult theory to prove since most of the knowledge about dinosaurs we extract from their bones. fossilized, which greatly limits how much we can know about their external appearance.
The size of the dinosaur is a relevant aspect. Prior to their discovery, most fossils showing feathers belonged to small dinosaurs . According to Corwin Sullivan, who was part of the study that described Yutyrannus :
“The idea that primitive feathers may have served as insulation rather than flight has been around for a long time. But animals with bulky bodies can retain heat very easily and, in fact, they tend to have more problems due to overheating of their body”.
So what use could Yutyrannus ‘s feathers have? The answer could lie in the climatic conditions in which this species lived . It inhabited areas of what is now the Asian continent during the Lower Cretaceous, between 140 and 120 million years ago, when it is estimated that temperatures in the region were lower than usual during this geological period. Tyrannosaurus rex lived in what is now North America during the Late Cretaceous, when temperatures were warmer, so this could be why it wasn’t covered in feathers. However, the option is not ruled out for some parts of your body. According to Xing Xu of the Beijing Institute of Vertebrate Paleontology and Paleoanthropology, who led the study:
“The feathers of Yutyrannus were simple filaments, more similar to the down of a modern chick than to the feathers of an adult bird.”
Another of the responses proposed to the plumage of a larger dinosaur is the use of this element in courtship , to show off and attract potential mates. Little by little, more and more points of view about the behavior of dinosaurs are being taken into account, something very difficult to study and with very little traceable evidence from fossils.
Yutyrannus was discovered as a result of three fossils with fairly good preservation conditions. One of the specimens is an adult, while the other two are in different juvenile phases, something very interesting to be able to study their growth. They were purchased from a vendor and came from the Yixian Formation , in the Chinese province of Liaoning, where they appeared in 2012.
The specific name, Yutyrannus huali , mixes Mandarin with Latin and means “beautiful feathered tyrant” . As the three fossils were found together, some specialists do not rule out the possibility that they hunted in packs. In any case, paleontologists hope to find new fossils that add new data to better understand the physiognomy and behavior of a species that has broken the rule about dinosaur plumage.
Cheung, R. 2012. T. rex has another fine, feathered cousin . sciencenews.org.
Rivera, A. 2012. A dinosaur related to the ‘T.rex’ discovered, but with feathers . elpais.com.
Xu, X. et al. 2012. A gigantic feathered dinosaur from the Lower Cretaceous of China . Nature 484, 92–95. DOI: 10.1038/nature10906.