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Gigantic Feathered Dinosaur Fossils Found in China

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An artist's conception of a group of Yutyrannus, now the largest-known feathered dinosaur, plus two Beipiaosaurus—the dinos who previously held the title. Image credit: Dr. Brian Choo

A new species of feathered dinosaur has been discovered, and its gigantic size makes it the largest-known feathered animal, living or extinct.

Yutyrannus huali lived in northeastern China 125 million years ago, according to a group of scientists in China, where three specimens of the bipedal tyrannosaur were found. A description of the new dinosaur is published in the March 5 issue of Nature. (Scientific American is part of Nature Publishing Group.)

Only a meter shorter than Tyrannosaurus rex, Yutyrannus weighed at least 1,400 kilograms and was nine meters long, or almost the length of a school bus, with filamentous plumage at least on its neck, pelvis and legs. The researchers think that the feathers, which in some cases were as long as a brand new No. 2 pencil, covered Yutyrannus’s entire body.

Image credit: Mr. Zang Hailong

Before now, Beipiaosaurus was the largest-known non-avian feathered dinosaur, and it was a huggable turkey-sized mass just two meters or so long. Scientists never expected to find plumage on a dinosaur as large as Yutyrannus, because, at least in mammals, larger-sized animals retain heat more efficiently than small animals. That puts larger animals at higher risk of overheating in warm weather, so insulative features such as feathers or fur are often lost in large mammals.

Yet Yutyrannus demonstrates that the loss of plumage is not necessarily a consequence of large size in dinosaurs. Xing Xu, a paleontologist at the Chinese Academy of Sciences’s Institute for Vertebrate Paleontology and Paleoanthropology, who led the study, said that Yutyrannus may be unique among gigantic dinosaurs because it lived in a climate that was cooler by eight degrees Celsius than other dinosaur habitats at that time—perhaps Yutyrannus needed the feathers to keep warm.

There is another possible explanation. Some gigantic maniraptoran dinosaurs (or “raptors,” a sister group to tyrannosaurs which includes extant bird species) are assumed to have possessed feathers, but direct evidence of plumage has never been found. If paleontologists find additional gigantic dinosaurs with feathers, it may be that dinosaurs are not governed by the same thermodynamic rules as mammals. That would certainly ruffle some feathers.

 





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  1. 1. RCWhitmyer 5:05 pm 04/4/2012

    At least on some modern animals fur and feathers protect the animal from the sun, and trap cooler air next to the body. Could not the feathers on dinos have done the same?

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  2. 2. Molecule 5:52 pm 04/4/2012

    “it may be that dinosaurs are not governed by the same thermodynamic rules as mammals” Very unlickely, because the ratio between volume and surface always help to limit external exchanges when the size increases and the aninal shape stays more or less identical (by the way it works for objects too :-) ). So for that hypothesis to work, large dinos would need a specific very efficient cooling organ we don’t know about (? … in fact I may have red something close to that, may be a special heart?). But anyways I was more adept to see the feathers as warming for small dinos (close to the body) and cooling for large one (away from the body = shade + water perspiration cooling effect). … Solved :-) … by the way actual birds can precisely adapt the thickness of their feathers to the temperature.

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  3. 3. RCWhitmyer 6:44 pm 04/4/2012

    @molecule I believe it’s thought the pulminary system was the same as birds which are very effective at O2 exchange (geese flying about a 6 mile altitude). Maybe they are more effective at exchanging heat also? T Rex panting like Rex the dog how cute.

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  4. 4. jtdwyer 11:58 pm 04/4/2012

    molecule – “…large dinos would need a specific very efficient cooling organ we don’t know about…”

    We may already know of one that might fit the bill: dinosaurs’ flow-through air sac breathing system certainly exposes more of their bodies’ internal surface area to external air flow and, as I understand, does not intermix incoming cool air with outgoing warm air…

    Link to this
  5. 5. jtdwyer 12:01 am 04/5/2012

    RCWhitmyer – My apologies – pulmonary…

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  6. 6. jtdwyer 12:06 am 04/5/2012

    The article states:
    “Yet Yutyrannus demonstrates that the loss of plumage is not necessarily a consequence of large size in dinosaurs.”

    I’ve heard some speculation that juvenile T.Rex’s had feathers, while adults did not. There is some evidence that these Y. huali specimens were juveniles of varying ages – perhaps in the process of losing their baby feathers… Please see: http://news.sciencemag.org/sciencenow/2012/04/researchers-unearth-largest-feat.html

    Link to this
  7. 7. Fanandala 3:32 am 04/8/2012

    I have read somewhere about a “primitive” type of feather. Could it have been like the plumage of an Ostrich, which protects the birds in both very hot and freezing conditions?

    Link to this

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