A huge feathered dinosaur

April 5, 2012 • 5:34 am

Fortuitously, I have a couple of biology posts lined up today. The first one, which comes Via Ed Yong, describes a huge new species of dinosaur that was covered with feathers. A new paper in Nature by Xu et al. describes the discovery in China of three nearly complete skeletons of Yutyrannus huali, a very large theropod dinosaur that was covered with filamentous feathers. (“Yu” is Mandarin Chinese for “feathers,” “tyrannus” is Latin for “king,” and “huali” means “beautiful” in Mandarin.)  The species is related to T. rex, also a theropod.

The beautiful feathered king was found in Liaoning Province, China, and here’s a slab preserving two of the specimens.  The line drawing tells you what you’re seeing.  These were very large individuals: the giggest weighed about 1414 kg, and the smaller ones, probably juveniles, about 600 and 400 kg respectively.  Those are big dinos: 1414 kg is 3,117 pounds, exactly the weight of a 1990 Volvo GLE.

Figure 1 | Yutyrannus huali (ZCDM V5000 and ZCDM V5001).
a, Photograph of the slab preserving ZCDM V5000 and ZCDMV5001. b, Line
drawing of the slab. Abbreviations: cav, caudal vertebra; cev, cervical vertebra;
dr, dorsal rib; dv, dorsal vertebra; ga, gastralia; lfe, left femur; lfi, left fibula; lh,
left humerus; lil, left ilium; lis, left ischium; lm, left manus; lp left pes; lr, left
radius; ls, left scapula; lt, left tibiotarsus; lu, left ulna;ma, mandible; pu, pubis; rc,
right coracoid; rfe, right femur; rh, right humerus; ril, right ilium; rm, right
manus; rp, right pes; rr, right radius; rs, right scapula; rt, right tibiotarsus; ru,
right ulna; sk, skull; sy, synsacrum.

According to the authors, the dino’s most striking feature is its “highly pneumatic midline crest resembling that of Guanlong and the carcharadontosaurian Concavenator. . “.  Here’s a reconstruction of the smaller Guanlong‘s cranial crest from Dinopedia (the beast was about 3 m long).  We don’t know what these crests were for: the color below implies one hypothesis, which was display. In other dinosaurs they might have been used to exaggerate sound production, but I’m not sure whether they’re hollow in  Y. huali.

Below is Figure 2 from the new paper, showing the skull and mandible of Y. huali. The crest is visible at the top of the skull, but it’s not as elaborate as that of Guanlong (see the reconstruction below).

The important feature here are the filamentous “feathers” that you can see in sections c-h of the photographs (click to enlarge):

According to the authors, the feathers (described as “filamentous integumentary structures,” are seen in all three specimens, are very long (15 cm, about 6 inches), and are found on the back and neck, on the forearms, and near the pelvis.  This implies that the whole damn beast was covered with filamentous feathers, and that’s seen in this artistic reconstruction from Ed Yong’s site:

Reconstruction of Y. huali by Brian Choo

What were the feathers for? Certainly not for flight, since these things are too big to either jump in the air (“ground up” theory) or glide down from trees (“trees down” theory), and at any rate the feathers are too thin to provide any lift. The authors suppose that they might represent “an adaptation to an unusually cold environment,”  since the species lived during a period of weather that was unusually cold during the Cretaecous. And although dinos were supposedly “cold blooded” (ectothermic), there’s some evidence that they were really “warm-blooded”; this is based on morphological evidence and the fact that these dinos might have been fast-moving rather than sluggish, which would require a high metabolism.

A reasonable theory, then, is that many theropod dinosaurs developed feathers for insulation, and these were later co-opted for flight.  This is supported by the finding of this new large beast with rudimentary feathers. (An alternative theory is that they were used for sexual or species-specific displays.) Since feathers supposedly evolved only once (I can’t disgorge the evidence for this, but that’s my recollection), then their use in flight would represent what Steve Gould called an “exaptation”: the evolution of a new function for a trait that originally evolved for a different one (penguins’ use of their flippers for underwater “flying” is another example).

Here’s where Yutryannus fits into the phylogenetic tree of tyrannosaurs.  The ones known to be feathered are shown as feathered, but it’s also possible that even T. rex itself was, as I suggested in WEIT, covered with fluff.  That would detract a bit from its fearsome reputation!

Figure 3 | A simplified cladogram showing the systematic position of
Y. huali among the Tyrannosauroidea. Silhouettes indicate body size and
possible extent of plumage. Different tyrannosauroids seem to have attained
gigantic body size independently in the Early and Late Cretaceous, but only in
the Early Cretaceous is there direct evidence of a gigantic form with an
extensively feathered integument. This may reflect the relatively cold climate of
the middle Early Cretaceous. See also Supplementary Information.


Xu, X., K. Wang, K. Zhang, Q. Ma, X. Xing, C. Sullivan, D. Hu, S. Cheng, and S. Want. 2012.  A gigantic feathered dinosaur from the Lower Creataeous of China. Nature online: doi:10.1038/nature10906

56 thoughts on “A huge feathered dinosaur

  1. For more coverage of this, including some excellent discussion about climate, see the post by Darren Naish, tyrannosauridologist, who was also one of the reviewers on the Nature paper:

  2. I read about this yesterday. Stories like this make me wish I had the maturity and discipline to be a science student in my formative years.

  3. The unknown artist is Brian Choo, according to the articles in Wired and BBC News.

    I’m not sure a feathered T. rex would be any less fearsome. Would you say the same about eagles? Or Dinornis?

    Why have so many feathered dinos been discovered in China? Presumably it’s something to do with the fineness of the rock that the were fossilised in… ?


    1. From Ed Yong’s post:

      “The problem is that none of the large tyrants was found in the right conditions. “Most T. rex skeletons were found buried in sandstone or siltstone. Both sand and silt are too coarse to record the presence of feathers even when they are there,” says Holtz. “But Yutyrannus was found in extremely fine sediments derived from volcanic ash and deposited in very still water: the perfect condition for preserving feathers.””

  4. I don’t know enough to comment on the fossil itself, but I’ve been interested in just how many important fossils–including arthropods–have been coming out of China over the past decade or so. It seems clear that more and more supposedly fatal “gaps” in the fossil record will close as the Chinese government has allowed more exploration by paleontologists.

  5. I read this “not blog” daily and while I enjoy the atheist, cat, cowboy boot and other posts, I look forward to the biology posts. Most I share with my daughters and wife and my wife shares some with her Montessori students.

    I should have put this under the appropriate post, but there were close to 200 comments there.

    What is cooler than learning about a recently discovered, feathered dinosaur? The interesting thing is that we may learn that feathered dinosaurs where more common or even the perhaps the majority.

    1. The majority, maybe. One of the comments in the Wired article:

      “It’s an exciting time to be a dinosaur paleontologist,” said [Mark] Norell [of the American Natural History Museum]. The feather findings “have rocked the world in terms of how we think of” dinosaurs, he said. “Instead of giant lizards, they were basically weird birds.”


  6. Feathers make it less scary? Don’t get near a Cassowarry if you think feathers make something wimpy!

  7. Jerry, I should have said in the other post as well, but your biology posts are the best, especially dinosaurs. It’s amazing to think just how different this planet was once.

    Just wondering if any one knows what kind of animals this dinosaur would have hunted and if they hunted say large animals in pacts or maybe smaller animals by themselves or perhaps they were even scavengers?


  8. It will be interesting to see if the paleontology of these beasts will give us hints about evolution of feather tracts. Did dinos also have them? Did some? As a bird-centric biologist (none of this feline nonsense!) These feathered dinosaurs certainly provide a thrill.

  9. Interesting how it ties in to the warm/cold blooded issue. Not sure that it favors either one, though; both cold and warm blooded species would find value in insulation.

    Being big is also a heat-retaining adaptation, so maybe even if they were ectothermic, being big was a way of reducing relative sluggishness.

    Last random thought; AFAIK modern cold-blooded reptiles can move very fast for short time periods. Its not that their ‘top speed’ is particularly low, its that they can’t maintain it for more than a few seconds. I have no problem thinking of these dinos operating as ambush predators. An ability to run at 40mph does not mean they did it for long periods. Leopards can run at 40mph too, but being ambush predators, they tend not to do it for more than a few seconds at a time either.

    1. both cold and warm blooded species would find value in insulation.

      Not true, I think. Insulation is diagnostic for endothermy.

      The rest of your comment is apposite, however.

      1. Insulation is diagnostic for endothermy.

        Please explain why a cold-blooded species would not want/need this type of insulation.

        Obviously some warm-blooded species use feathers for it (among other uses), but I’m not sure why feathers wouldn’t also be useful for cold-blooded species to retain heat.

        1. Because an ectotherm by definition needs to let external heat in, and insulation would prevent this. If the animal is producing internal heat that needs to be retained, it is by definition an endotherm.
          Something this big would probably produce enough internal heat to benefit from insulation even if it had a ‘low’ metaboic rate at rest. i.e. it would be at least partially endothermic.

          1. Wouldn’t an ectotherm also benefit from an adaptation that allows them to trap internal heat in, when the environmental temperature drops below their body temperature?

            I think my understanding of feathers is poor. I thought the could be arranged to help insulate, but that they could also be arranged to help ‘let in’ heat. If so, there is no particular reason why they would be a bad adaptation for a cold-blooded critter. Obviously not required, but not contra-indicative of an ectothermic system, either.

            The simplest example of how it might work would be: stick lightly feathered head under feathered limb when you want to preserve heat. Stick head out when you want to absorb it. Birds to that. Can’t see why dinos couldn’t.

      2. IIRC, dinosaur predator/prey ratios are consistent with endothermy. Or homeothermy. Or both. This was one of the arguments in Julian May’s The Warm-Blooded Dinosaurs. Which I read about 35 years ago.


    2. Supposedly the warm blooded ostrich can run at 70 kph [43 mph] for up to 30 mins [I couldn’t find a reliable source for that info other than Wiki]. Another Wiki (sorry 🙂 ) I’ve read recently claims that the terms “warm/cold blooded” are falling out of favour. See HERE

  10. Seems to me that feathers could have served one or more functions: insulation/temperature regulation, display/camouflage, some protection against biting insects/parasites, nesting material, probably many not thought of. I find this intensely interesting which is one reason why I typically don’t comment on the biology articles. Firstly, I’m not a scientist (just in my dreams) and, secondly, when I read such an article, I immediately take a trip into deep time with my imaginary Nikon D3, a 300mm 2.8 lens and a really big SD card. So, you guys make the comments. I’m taking photos of these beautiful dinosaurs. Later.

  11. I don’t usually comment, but I wanted to tell you, I like the biology posts. 🙂 Feathered dinos are just plain awesome.

    It’s hard to find quality science discussions online, with out either paying for it, or having to spend hours digging through journals.
    So, from this cat loving, atheist engineer, thanks!

  12. Presumably Yutryannus is its nom de plume?
    Not read it but –
    Feathers: The Evolution of a Natural Miracle
    Thor Hanson Basic Books: 2011.
    The Nature review by Alan Brush said
    “Hanson’s tale is comprehensive, accurate, timely and engaging. One thing missing is the story of the technical breakthroughs that led to the understanding of feather structure (keratin) and genomics…
    In the late 1960s, a group in the protein-chemistry division of the Commonwealth Scientific and Industrial Research Organisation in Australia isolated and identified the soluble monomer of feather keratin, and revealed the characteristics of the gene family involved. Ornithologists quickly became interested. This accomplishment provided ways to test directly the ‘feathers arose from scales’ hypothesis and to map molecular evolution more widely onto lineages derived from other features. Comparative work on the proteins of the other epidermal structures, such as claws, scales and beaks, soon followed.”

  13. Well, speaking as someone whose distant ancestors evolved in an environment relatively free of predation from giant birds, I can tell you that feathers probably would make a predator seem a bit less scary.

    Had these tyrannosaurids lived back then and there, (and if this counterfactual made any sense), then I and others today would naturally think otheriwse.

  14. Why would it have to be one or the other?

    “developed feathers for insulation” OR “used for sexual or species-specific displays”

    Why not both, and maybe other things too? A physical structure will often have multiple effects on an organism’s interactions with its environment — sometimes positive and other times negative. Some effects strongly positive, and others weakly so. Some strongly positive part of the year, or under certain circumstances, but perhaps weakly negative at other times.

    Evolution is like a tangled bank. There’s a lot going on.

  15. I admit to reading this piece out of pure guilt! But I am extremely glad that I did. That was fascinating. Thank you so much.

    *must make more of an effort*

  16. Wow, Chinese dinosaurs were 1990 Volvos?

    Who knew??

    Do you think they had 16 valve 4 cylinder hearts and a hard time starting in the morning?

    Probably good in snow, too, which would explain the feathers.

    I can, however, understand the extinction.

  17. Terminology quibble: the latin for “king” is “rex”. A “tyrannus” could be a king, but it originally meant “usurper” and later something like “dictator”.

    1. If a volvo-sized carnivore wants to be called “king” instead of “dictator,” I suggest we don’t argue with him. 🙂

  18. Ho ho ho, let’s see what Feduccia has to say about this!

    I’m surprised Jerry’s using words like “warm-blooded” and “cold-blooded,” since afaik those are outdated terms. Instead you have to at least break animals up into:

    1.ectothermic/endothermic – which tells you whether they produce their own heat to regulate their body temperature, and
    2.homeothermic/poikilothermic – which tells you whether they can tolerate changes in core body temperature or not.

    It’s hypothesized that some large dinosaurs were “intertial homoeotherms,” meaning they experienced only small fluctuations in their body temperature, like you and me, but unlike you and me they accomplished this by using their large volume/surface area ratio to keep themselves from losing much heat, whereas humans accomplish this via our faster metabolisms.

    Now, can an inertial homeotherm (or any kind of ectothermic homeotherm, for that matter) move as quickly as an endotherm? The answer to that question is not something I can recall off the top. If the answer is no, then I suppose any fast-moving dinosaurs would have had to be endotherms.

    1. Both a crocodile and a Komodo dragon (among the larger contemporary ectothers) would outrun you over a short distance. The benefits of high aerobic metabolic rates are more along the lines of endurance, not sprint-speed.

      homeothermic/poikilothermic – which tells you whether they can tolerate changes in core body temperature or not.

      Well, it’s really about the range of body temperatures experienced, not necessarily tolerance of differences. For tolerance specifically, the terms ‘eurythermis’ and ‘stenothermic’ can be used.

      1. Good to know.

        Regarding the last point, I’m not clear on the difference between what temps can be experienced vs. tolerated. *Any* animal can freeze or overheat under the right conditions, so if “experience” means what it normally does, there doesn’t seem to be any limitation on that range….

  19. It’s fascinating how much our knowledge on this subject has advanced since I was a kid. 20 years since Jurrasic Park and were they to do a remake it would look completely different. I didn’t know what I was missing when I got bored with dinosaurs!

  20. Great post. I rarely comment, even on Jeebus and cat posts, but wanted to let you know that I like the science posts.

  21. I liked this when I saw it on the news, I had previously seen that they thought some T.Rex had feathers on “How to Build a Dinosaur” on BBC, and knew about Archeoptryx, and have been hoping for more feathered dinosaurs to be found.

    This is an interesting discovery 🙂

  22. That red supra-nasal crest (for lack of a better term) looks like an enormously bad adaptation – just the sort of thing that other dinosaurs would presumably find easy to nom onto. Unless perhaps the effect was to keep the predator away from the victim’s neck.

  23. I’m just glad this won’t be mentioned on NY school standardized tests. Kids would freak out from the sheer coolness of it and be unable to focus on the actual test material.

  24. For the crest, my intuition is that it was used as an amplification chamber for mating calls. Just an intuition, but seing what has been achieved in modeling Parasaurolophus’ calls by studying their crest, I like to think that’s the bunny…

  25. Jerry,

    There is a error in your piece!

    (“Yu” is Mandarin Chinese for “feathers,” “tyrannus” is Latin for “king,” and “huali” means “beautiful” in Mandarin.)

    The beautiful feathered king

    Apparently tyrannus is Latin for tyrant.
    (Rex is latin for king)
    So it’s actually…

    The beautful feathered tyrant

  26. These were very large individuals: the giggest weighed about 1414 kg, and the smaller ones, probably juveniles, about 600 and 400 kg respectively. Those are big dinos: 1414 kg is 3,117 pounds, exactly the weight of a 1990 Volvo GLE.


    I have trouble getting my kids to understand this, but I’m disappointed to see professional scientists not understanding significant digits.

    1. Oh for God’s sake. Sorry to disappoint you, and I suggest that you frequent another website so as to avoid this disappointment.

    2. 1 kilogram is sufficiently small that it’s perfectly reasonable to call such a weight “exact” ; add a pair of jumper cables to the car and you’ve made up the difference.

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