Animals

Shaggy T. Rex Cousin Was Heftiest Feathered Dino

This 3,086-pound tyrannosaur was no songbird, but a fierce hunter.

THE GIST

- A new dinosaur species related to T. rex may be the world's largest known feathered animal.

- The body of the dinosaur was either mostly or completely covered with downy feathers.

- The feathers were not suitable for flight, but instead likely served as insulation and decoration.

A 3,086-pound shaggy tyrannosaur was the world's largest known feathered animal -- living or extinct -- according to a paper in the latest issue of Nature.

The newly unearthed tyrannosaur, named Yutyrannus huali or "beautiful feathered tyrant," lived about 125 million years ago in northeastern China. The over 29-foot-long non-avian dinosaur, represented by three specimens, is considerably smaller than its infamous relative T. rex, but some 40 times the weight of the largest previously known feathered dinosaur, Beipiaosaurus.

"The largest specimen preserves feathers on the tail, and two smaller specimens preserve feathers over the neck, on the forelimbs, near the pelvis, and even feet," lead author Xing Xu, a professor at Beijing's Institute of Vertebrate Paleontology and Paleoanthropology, told Discovery News.

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Xu and his colleagues analyzed the remains of the three dinosaurs and discovered that patches of filamentous structures were near the bones on the slabs containing the specimens. The researchers believe that when the dinosaurs were alive, these simple structures would have been more like the fuzzy down of a modern baby chick than the stiff plumes of an adult bird.

The feathers likely served two functions: insulation and decoration.

"The size, structure and extent of the feathers suggests that they would have formed a shaggy body covering that would have had at least some insulating function," co-author Corwin Sullivan told Discovery News. Sullivan is a Canadian paleontologist now based at the Beijing institute.

Large animals, like elephants, are usually not feathery or furry. That is because these beasts have a tendency to overheat. The new dinosaur, however, lived during the middle part of the Early Cretaceous, when temperatures are thought to have been relatively cool.

Previously it was thought that only certain smaller dinosaurs were feathered. The scientists still think that feathers first emerged in a smaller dinosaur, and that larger feathered dinos only came along later.

"However, that doesn't mean that small feathered dinosaurs disappeared," Sullivan said. "New small species continued to appear as well."

Some of these smaller species eventually evolved into today's modern birds.

This meat-loving non-avian dinosaur, however, was no tiny songbird. Like T. rex, it appears to have been a fearless hunter.

Xu thinks that the feathered dinosaur hunted in a pack.

"We have evidence that the three individuals we reported in the journal paper were hunting a large sauropod dinosaur when they died from unknown reasons," he said, adding that a volcano eruption could have done in the dinos.

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Their feathers suggest that extensive, insulating plumage was more widespread than previously realized. The most primitive feathers did not have aerodynamic surfaces capable of generating lift for flying, but they could have functioned as decoration.

"Depending on their coloration and patterning, they might have been useful in display," Sullivan explained. "Note that this doesn't necessarily mean a performance, like a courtship dance."

He added, "If the feathers were strikingly patterned, for example, they could have simply been attractive to potential mates, and that could be considered a display function."

Prior research, along with this new study, suggest that non-avian dinosaurs were either scaled or feathered. No dino was furry, since fur evolved on the mammalian branch of the vertebrate evolutionary tree, whereas feathers evolved on the reptilian branch.

An artist's impression of

Sept. 15, 2011 --

A stunning array of prehistoric feathers, including dinosaur protofeathers, has been discovered in Late Cretaceous amber from Canada. The 78 to 79-million-year-old amber preserved the feathers in vivid detail, including some of their diverse colors. The collection, published in this week's Science, is among the first to reveal all major evolutionary stages of feather development in non-avian dinosaurs and birds. In this slide, an isolated barb from a vaned feather is visible trapped within a tangled mass of spider's web.

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"These specimens were most likely blown into the tacky resin, or were plucked from an animal as it brushed against resin on a tree trunk," lead author Ryan McKellar told Discovery News. "The fact that we have found some specimens trapped within spider webs in the amber would suggest that wind played an important role in bringing the feathers into contact with the resin," added McKellar, a postdoctoral fellow at the University of Alberta's Department of Earth and Atmospheric Sciences. The feather filaments shown here are similar to protofeathers that have been associated with some dinosaur skeletons.

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McKellar and his team made the discovery after screening over 4,000 amber samples from Grassy Lake, Alberta. The amber, collected by the Leuck family, is now housed at the Royal Tyrrell Museum. The researchers ruled out that the inclusions were mammal hairs, plant or fungal remains based on their structure. Some dinosaur fossils retain skin impressions, so the scientists could match dinosaur protofeathers (hair-like projections) to some of the objects within the amber. Here, a feather is visible near a plant bug. The high number of coils in the this feather suggests it could have come from a water-diving bird.

The translucent tree resin provides a window into feather evolution, from non-avian dinosaurs to birds. "Part of what makes this particular set of feathers interesting is that we find the very simple Stage I and II feathers alongside advanced feathers that are very similar to those of modern birds, Stages IV and V," McKellar said. The researchers aren't yet certain why feathers first evolved, but the density of the protofeathers suggests that they helped dinosaurs with regulating temperature. Dinosaurs such as Troodon or Deinonychus may have produced the feathers. The cork-screw shaped structures in this slide are the tightly coiled bases of feather barbules.

As feathers continued to change, they developed tufts, barbs, branching features, little hooks, and more. Some of the most advanced feathers in the collection are comparable to those of modern grebes. They appear to help diving, indicating that some of the prehistoric birds were divers. McKellar suspects the marine birds might have been Hesperornithiformes, a specialized flightless diving bird from the Dinosaur Era. This is a white belly feather of a modern grebe, showing coiled bases comparable to those seen in the Cretaceous specimen.

Some of the feathers appear transparent now, but would have been white in life. A range of colors for the feathers is evident, though, with grays, reds and various shades of brown preserved. This, and prior research, suggests that non-avian dinosaurs and prehistoric birds could be quite flashy. The pigment within this fossilized feather suggests it would have originally been medium- or dark-brown in color.

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In an accompanying "Perspectives" article in Science, Mark Norell points out that the dinosaur Sinosauropteryx is thought to have had a reddish banded tail, while Anchiornis likely possessed a striking black body, banded wings and a reddish head comb. Norell, chair and curator of the American Museum of Natural History's Division of Paleontology, told Discovery News that the newly discovered feathers are "very exciting." Here, a feather barb within Late Cretaceous Canadian amber shows some indication of original coloration.

Some dino aficionados have wondered if DNA could be extracted from the feathers. "Almost anything is possible," Norell said, quickly adding that most DNA-extraction studies have been conducted on much younger amber, dating to around 20-30 million years ago, and even those led to questionable results. "Maybe bits and pieces could be identified, but not the whole genome." Shown are 16 clumped feathers in Late Cretaceous amber.

People with amber objects, such as jewelry, also probably don't have prehistoric feather inclusions, since such items are extremely rare and dealers isolate the best pieces. Nevertheless, McKellar said, "There is some hope that you could have small feather fragments that have been overlooked." An unpigmented feather and a mite in Canadian Late Cretaceous amber.