An international team of paleontologists has discovered fossils of the largest feathered dinosaur known to date.
An artist’s impression of a group of Yutyrannus huali and two individuals of the smaller Beipiaosaurus (Brian Choo)
The paper in the journal Nature describes a gigantic new basal tyrannosauroid, Yutyrannus huali, on the basis of three nearly complete skeletons found in the Lower Cretaceous Yixian Formation of western Liaoning Province, China.
The team, including researchers from the University of Alberta and five Chinese institutions, notes that these three specimens were acquired from a fossil dealer who stated that they were collected from a single quarry. However, the dealer could not provide accurate information as to the exact quarry in which the specimens were collected.
Yutyrannus lived in what is now northeastern China about 125 million years ago and weighed at least 1.4 tons.
The body length of this creature is estimated to be about 9 meters.
The paleontologists also note that Yutyrannus shared some features, particularly of the cranium, with other tyrannosauroids. However, morphometric analysis suggests that Y. huali differed in its growth strategy.
The skull of Yutyrannus huali (Xing Xu et al)
“The feathers of Yutyrannus were simple filaments,” explained Prof. Xing Xu of Beijing’s Institute of Vertebrate Paleontology and Paleoanthropology, a lead author of the study. “They were more like the fuzzy down of a modern baby chick than the stiff plumes of an adult bird.”
The name of the creature means “beautiful feathered tyrant” in a combination of Latin and Mandarin.
As a living animal, Yutyrannus was smaller than its infamous relative Tyrannosaurus rex, but about 60 times as heavy as Sinocalliopteryx and 40 times as heavy as Beipiaosaurus, previously ranked as the largest known feathered non-avian dinosaurs.
“The idea that primitive feathers could have been for insulation rather than flight has been around for a long time,” said Dr. Corwin Sullivan, a Canadian paleontologist and a co-author of the study. “However, large-bodied animals typically can retain heat quite easily, and actually have more of a potential problem with overheating. That makes Yutyrannus, which is large and downright shaggy, a bit of a surprise.”
The discovery of Y. huali provides direct evidence for the presence of extensively feathered gigantic dinosaurs and offers new insights into early feather evolution.
“Yutyrannus dramatically increases the size range of dinosaurs for which we have definite evidence of feathers,” Prof. Xu said. “It’s possible that feathers were much more widespread, at least among the meat-eating dinosaurs, than most scientists would have guessed even a few years ago.”
