The filamented Psittacosaurus

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By now most people with even a passing interest will be aware of the fact that there are now a number of specimens (and indeed species) of ornithischian dinosaurs that are preserved with some form of filament-type structure which, superficially at least, bear some resemblance to primitive feathers. However when the first candidate was announced, this specimen of Psittacosaurus housed in Frankfurt, it inevitably causes something of a furore with many suspicious of the data and suggestions that the filaments were simply coincidentally preserved plant stems or something similar.

The discovery of multiple specimens of Tianyulong inevitably make this rather more plausible as a real find, though of course a few more filamented Psittacosaurus would be nice. A third taxon is apparently now know but sadly illness led to a no-show at SVP so few have seen anything of this new find. Still, the original find is an impressive specimen, but doesn’t seem to have really been thoroughly described or illustrated too well and as I’m in a position to at least partially rectify that, here’s some photos I took of the specimen on my recent trip.

I have actually seen this before years ago but extremely briefly, and have also seen a superb cast of it in the Carnegie (my photo of which actually popped up in a dinosaur text book recently, [with permission I should add] such was the quality of the copy). However, I’d never really *looked* at it properly and actually spending a few minutes (even through a glass case) reveals some lovely details.

First off, it’s big. The biggest specimen I’ve seen by far for this genus, though the head is not that large compared to the rest of the body. Then there is skin pretty much everywhere – this does turn up in Liaoning not too infrequently, but rarely to this extent or quality. It covers large chunks of the animal and even completely covers large chunks of the bones in places (just look at the femur) and it looks like there’s a pile of gastroliths in the gut that are also covered.

While I’d be very cautious about interpreting the extent of the skin as being directly linked to other soft tissues, the extensive ‘flap’ behind the hindlimb would correspond with what you might expect from large retractor muscles there and so might well be genuine. Not only that, but there’s quite a bit of texture to the skin and in a couple of places it appears to have a different surface texture to others (see the underside of the base of the tail, and the area around the toes), which could also be genuine. On top of that, both the individual scales are clear in some places, and are even coloured differently (the larger ones are black) implying at least the possibility of this representing a pattern on the animal, and this changes along the body (look a the concentration in the tail, compared to the legs) though again:caution. It does look rather like this little patch that I featured years ago which is rather neat. Finally, this pattern also extend onto bones that are not obviously covered with skin (see the distal forelimb for example) with apparently the stains or some other taphonomic artefact of the scales left on the bones themselves.

And yes, then there are the filaments. Sprouting up off the base of the tail and extending most of the way along its (incomplete) length. They are rather thick and clearly somewhat stiff, but also flexible enough to bend under their own weight. While not a common reference, they look a lot to me in terms of  their apparent properties like the tail hairs of giraffe (though much, thicker). It’s a real shame they are at least in part cut off the edge of the slab, but certainly appear to have stopped appearing well short of the end of the tail, so their full extent does appear to have been preserved.

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I think that’s everything I can reasonably (or even unreasonably) speculate about this specimen without, yknow, actually going back and reading the original paper and associated commentary. However, the really key thing is of course that here’s some nice pictures of this and it gives a welcome opportunity to revisit this important and interest specimen.

18 Responses to “The filamented Psittacosaurus”


  1. 1 paleomanuel 13/11/2013 at 2:04 pm

    These photos remind me the feeling that we might never recognize a living dinosaur … (Except birds obviously)
    Thanks for the pics, this specimen deserves proper illustration for sure!

  2. 2 microecos (@microecos) 13/11/2013 at 4:52 pm

    Awesome photos. I hadn’t appreciated how interesting the *rest* of the integument is (as you point out). The pattern of scales on the on the manus looks A LOT like a ratite foot (ostrich in particular). Not surprising, but nice to see.

  3. 3 Mike Keesey (@tmkeesey) 13/11/2013 at 5:39 pm

    Are those scutes around the shoulder?

    • 4 David Hone 13/11/2013 at 5:50 pm

      I really don’t know. They clearly are larger there, and that lone one *could* be displaced, but looks more like it’s sticking out of the specimen and implies that it’s extending from the material as some more pronounced thing. I wouldn’t bet against it, sure, but I wouldn’t want to say they certainly are.

  4. 5 Denver Fowler 13/11/2013 at 6:54 pm

    Fantastic photos. Many thanks for sharing!

  5. 6 Raven Amos (@alaskanime) 13/11/2013 at 8:33 pm

    Wow, the pebbling on the legs reminds me a lot of a plucked chicken at first blush.

  6. 7 Tracy L. Ford 13/11/2013 at 8:58 pm

    Nice photos. It’s rather odd that the long filaments are behind the tail skin and not sprouting from the top of the tail.

    • 8 David Hone 13/11/2013 at 9:26 pm

      But then I don’t think it’s quite on it’s side – sure the tail verts are lined up like that, but look at the skin along the dorsals, it’s not really in the pattern you’d quite expect and the head and dorsals positions suggests some rotation of the body on the long axis, or compression of the specimen oddly. So I don’t think that’s a major issue here, so much as, potentially at least, just a slight anomaly thanks to the vagaries of compressing a 3D animal into sort-of 2D.

  7. 9 David Bump 13/11/2013 at 10:22 pm

    To someone not enthralled with the idea of seeing living dinosaurs and all that, the presence of long filaments on dinosaurs clearly not anywhere close to becoming gliders or flyers simply reminds us that convergence and parallelism have been described many times, and suggests the possibility that the fuzzy bird-like dinosaurs may have been nothing more than that, dinosaurs with some bird-like features and fuzz that had features making it biologically distinct from feathers, though only apparent in the living creatures.

    • 10 Mike Keesey (@tmkeesey) 14/11/2013 at 12:24 am

      The close relation between basal pygostylians and other eumaniraptors is supported by hundreds of osteological characters, not just integument.

    • 11 Mickey Mortimer 14/11/2013 at 12:48 am

      To someone who examines the evidence objectively, the possibility feathered theropods are unrelated to birds was thoroughly debunked in the 1970s and has only become less tenable since. This has escalated to the point where Prum (2003) justifiably questioned whether the Birds Are Not Dinosaurs crowd were even doing science anymore. You commit the same error as Feduccia and Martin here, using your assumption of why feathers should evolve to constrain your evolutionary hypothesis. Far more likely feathers were ancestral to dinosaurs or ornithodirans (pterosaurs+dinosaurs) and evolved for another function, such as insulation.

      Prum, 2003. Are current critiques of the theropod origin of birds science? Rebuttal to Feduccia (2002). The Auk. 120(2), 550-561.

  8. 12 jrabdale 14/11/2013 at 1:24 am

    I imagine that a lot of paleo-artists will be illustrating Psittacosaurus as being colored in a tan and dark brown “tortoise shell” pattern from now on – I know I certainly will. True, it may not be the actual color pattern present in this genus (the fossilization process almost certainly distorted the colors to be of a more earthier palette), but is is aesthetically pleasing. I’m also sure that someone out there is wondering whether or not this specimen can be tested for the presence of melanosomes, like Anchiornis. It would be interesting to see what would arise from that.

    I also suppose that someone wants to take a section-slice from that weirdly-shaped glob in the center of the animal’s ribcage. This is almost certainly the solidified remnants of its last meal. Analysis of this may prove once and for all whether Psittacosaurus was omnivorous or herbivorous.

  9. 13 Stevie Moore 14/11/2013 at 3:26 am

    These are some beautiful images. Although there is nothing ‘bad’ about the cast in Pittsburg, These images of the actual specimen show me so much more detail in the scales, filaments, and as mentioned previously, the color. Thank you so much for sharing this!

    • 15 Tracy L. Ford 14/11/2013 at 10:26 pm

      A number of Ornithischians? What the number? Three? Psittacosaurus, Tianyulong, and the ornithischan that was going to be talk about at the SVP, which unfortunately due to illness it wasn’t given. What other ‘feathered’ ornithischians are there? I keep a list of feathered dinosaurs on my website http://www.paleofile.com and would love to list all of them in it.


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