Tetrapod Zoology

When there’s no time for anything else, at least I can recycle text from the aborted field-guide (see bottom for previous excerpts). Hmm, I really should get that published. Anyway…

i-fdefa0d14ee140641cdd274161620d77-Protopteryx_Zhang_&_Zhou_2000_April-2010.jpg

Protopteryx fengningensis was named in 2000 for two specimens discovered in the Yixian Formation of Fengning County, northern China [adjacent figure from Zhang & Zhou (2000): the tail feather shown in C belongs to Confuciusornis, not Protopteryx]. It’s an enantiornithine about the same size as a modern starling. As is common among Cretaceous birds, it had teeth in both its premaxillae and dentaries. Its snout was pointed, its foot claws were long and curved, and its metacarpal and carpal bones were not fused together. The latter is a primitive feature and one of several which indicate that Protopteryx was outside the clade that included the ‘more advanced’ enantiornithines. All three of its fingers had small curved claws and – as in modern birds and some other feathered maniraptorans – the thumb supported an alula.

i-f68e13b53864f79b17733a39935dd74f-protopteryx_reconstrucao__zhou_zheng_2001_April-2010.jpg

Down feathers and flight feathers covered the body and wings of Protopteryx, but what makes it unusual are the two elongate central tail feathers, each of which is about as long as the head, neck and body combined [adjacent reconstruction from here]. Similar structures have more recently been described in Dapingfangornis sentisorhinus Li et al., 2006 and Paraprotopteryx gracilis Zheng et al., 2007. Because these feathers lack barbs they superficially recall gigantic scales, leading some experts to suggest that they represent an early stage in feather evolution (Zhang & Zhou 2000). However, some living birds possess long display feathers which also look scale-like or even recall strips of plastic, so this conclusion does not necessarily follow.

It’s probably only a matter of time before someone works out what colour these structures were in life: the integumentary structures of Sinosauropteryx, Anchiornis and Psittacosaurus have all recently been reported to preserve their original pigments.

Ref – -

Zhang, F. & Zhou, Z. 2000. A primitive enantiornithine bird and the origin of feathers. Science 290, 1955-1959.

For other articles on Mesozoic birds see…

For previous bits and pieces from the aborted field guide project see…

Comments

  1. #1 TEO
    April 12, 2010

    The King-of Saxony bird of paradise (Pteridophora alberti)comes to mind. The long plumes at the sides of the head lack any trace of barbs and look pretty much like little plastic flags:

    http://vireo.acnatsci.org/gallery.html?mode=show&gallery=1

    There’s a photo in the same page of the Scale-feathered cuckoo. The tips of the feathers look like shiny plastic, too.

  2. #2 Darren Naish
    April 12, 2010

    While I’m here it’s worth citing…

    Peters, W. S. & Peters, D. S. 2009. Life history, sexual dimorphism and ‘ornamental’ feathers in the Mesozoic bird Confuciusornis sanctus. Biology Letters 5, 817-820.

    The display feathers of Confuciusornis are not ‘in pin’ as one worker has stated: the shafts are long and strap-like, with barbs and calami visible only at the expanded tips and adjacent to them (Chiappe et al. 1999). That’s really weird, as living birds with strap-like tail feathers lack vane differentiation entirely.

    Chiappe, L. M., Ji, S.’A., Ji, Q. & Norell, M. A. 1999. Anatomy and systematics of the Confuciusornithidae (Theropoda: Aves) from the late Mesozoic of northeastern China. Bulletin of the American Museum of Natural History 242, 1-89.

  3. #3 Anonymous
    April 12, 2010

    I knew about Anchiornis and Sinosauropteryx, but not Psittacosaurus. Wow! Link to possible sources please?

  4. #4 Darren Naish
    April 12, 2010

    It’s worth citing all the papers in one place…

    Sinosauropteryx

    Zhang, F., Kearns, S. L., Orr, P. J., Benton, M. J., Zhou, Z., Johnson, D., Xu, X. & Wang, X. 2010. Fossilized melanosomes and the colour of Cretaceous dinosaurs and birds. Nature 463, 1075-1078. [abstract]

    Anchiornis

    Li, Q., Gao, K.-Q., Vinther, J., Shawkey, M. D., Clarke, J. A. D’Alba, L., Meng, Q., Briggs, D. E. G. & Prum, R. O. 2010. Plumage color patterns of an extinct dinosaur. Science 327, 1369-1372. [abstract]

    Psittacosaurus

    Lingham-Soliar, T. & Plodowski, G. 2010. The integument of Psittacosaurus from Liaoning Province, China: taphonomy, epidermal patterns and color of a ceratopsian dinosaur. Naturwissenschaften doi: 10.1007/s00114-010-0661-3 [abstract]

    Commenter in comment 3: why have you taken to being anonymous all the time? I’d prefer it if you weren’t (anonymous people usually practise anonymity because they have something to hide).

  5. #5 Raptor
    April 12, 2010

    Wait.. now it was always my understanding that feathers were not so much modified scales, but were more like hair. They emerge from a hollow tube in a corkscrew manor, unfold, and then when the feather is mature, the blood supply is cut off, and the hollow tube falls off, leaving the feather. So, I would expect, a more primitive feather to look more like hair and less like scales. Though I know birds have scales on their feet, with recent discoveries of various hair-like features on certain dinos and pterodactyls, I have to wonder if hair is not modified scales and feathers modified hair. And I have to wonder which it is. Are feathers scales or are feathers hair (or are they something else completely)? And like you said, just because it lacks the barbs, does not make it more primitive. Though, it also makes me wonder why these long feathers form that way. Would be interesting to do some strength/flexibility/durability tests in them vs other feathers with barbs. Maybe even toss in time and energy it takes to form them, as I know a lot of birds drop these ornamental feathers to regrow new ones for the next year.

  6. #6 Nick Gardner
    April 12, 2010

    “Commenter in comment 3: why have you taken to being anonymous all the time? I’d prefer it if you weren’t (anonymous people usually practise anonymity because they have something to hide).”

    I don’t agree… anonymity is a beautiful right of the Internet :)

  7. #7 I. M. Anonymous
    April 12, 2010

    Nick: I agree!!

    ps – I followed you home yesterday, nice curtains!

  8. #8 Zach Miller
    April 12, 2010

    Totally not convinced about the psittacosaur color. You’re telling me that the pigment bled out of the skin cells directly onto the surrounding…ground, and fossilization did not alter the colors? The authors also use some strange dolphin analogy to explain how the skeleton looks “wrapped” in skin, but that seems like a HORRIBLE comparison for Psittacosaurus.

    I’m surprised I haven’t read anyone’s opinion of this paper on the blogosphere, actually.

  9. #9 Riggy
    April 12, 2010

    Any plans on trying to extract melanosomes from the scales of preserved hadrosaur skin?

  10. #10 John Harshman
    April 12, 2010

    Raptor:

    Time to cite Prum, R. O., and A. H. Brush. 2002. The evolutionary origin and diversification of feathers. Quarterly Review of Biology 77:261-295.

    Is that what you were thinking of?

  11. #11 Dartian
    April 13, 2010

    Nick:

    I don’t agree… anonymity is a beautiful right of the Internet

    I can see the merits of not revealing your identity on the Internet; I myself don’t post comments under my own name*, for a number of reasons. But if you still want to take part in the online discussion (rather than keep lurking), why don’t you invent yourself a pseudonym, and stick to it? Posting as ‘anonymous’, or as ‘anon’, is unimaginative and sometimes downright confusing for the other commenters.

    * This blog’s owner, i.e., Darren, knows my real name, however; I’m not ano- or pseudonymous to him.

  12. #12 David Marjanović
    April 13, 2010

    and sometimes downright confusing

    It does happen that two or more people with the pseudonym “Anonymous” comment in the same thread.

  13. #13 Anonymous
    April 13, 2010

    …Ookay…anyway, I’m not sure what to make of the Psittacosaurus one though, seeing as the authors seem to be subscribing to the theory that dinosaur proto-feathers are really just displaced collagen fibers.

  14. #14 Daniella Perea
    April 13, 2010

    Mayr recently published a response to one of the Lingham-Soliar psittacosaur papers. Two words on Lingham-Solair’s dino-skin papers.. crap science.

  15. #15 Cale
    April 13, 2010

    I might add that in other internet circles…. ‘Anonymous’ has a very sinister ring to it. “Hackers on Steroids,” “The Internet Hate Machine,” 4Chan, /b/, etc. Ignore this if none of these phrases ring a bell to any of you.

    However I do support people’s rights to be Anonymous online.

    And getting back to the point of the post, I notice that the fossil feather shown next to the reconstruction has a reddish tint to it, and the reconstruction has red tail feathers. Is this accurate then?

  16. #16 Jerzy
    April 13, 2010

    So, what birds, besides one bird of paradise, have larger plastic-like structures?

    I guess this is more an artifact of poor preservation – details being invisible.

  17. #17 Kelly Clowers
    April 13, 2010

    @Cale
    I think that’s overreacting a bit, that anon can be somewhat scary, but it is generally pretty clear when a post comes from one of them. And to encounter them on something like scienceblogs (much less one as technical as TetZoo) would be very unlikely (well, maybe /sci/entists would show up here, but the others really aren’t like /b/tards).

    In general, I have to agree with both Nick @ 6 and Dartian @ 11. Total anonymity can be great in the right situation (and should almost always be an option), otherwise, pseudonymity is often more useful. And of course, sometimes a real name works just fine.

  18. #18 CS Shelton
    April 13, 2010

    This raises the question the scale/feather discussion again, which I find very intriguing. Like I did on a previous thread, I’m going to use T-rex and the ostrich as my examples: If tyrannosaurs were once feathery and later evolved to be scaly, how did that process work? No modern birds have gone scaly to the degree tyrannosaurs did, and why not? It’s not like ratites need feathers, really. And why bare skin for their heads and legs (in the case of ostriches)? Don’t they get sunburned more than a scaly beast would?
    Basically, I’m thinking about what you can regain once you’ve lost it. No pygostylian has grown a tail, no modern bird has a scaly torso, etc. T-rex tells us you can get scaly again after an evolutionary period of being mostly downy. There’s been discussion of how scales turned into feathers. I wanna know how it works in reverse.

  19. #19 Cale
    April 13, 2010

    Kelly: As an avid reader of Encyclopedia Dramatica, I have to disagree as I’ve seen many ‘ruined lives’ documented there.

    However I DO agree that it’s pretty much a moot concern for a science blog….. /b/tards tend to prefer ‘easier’ targets. That being said, in many internet circles using ‘anonymous’ as a name will automatically raise eyebrows.

    Getting back to what I asked before…. it can’t be that simple, can it? Or am I missing something? The fossil tail feather looks reddish, and the reconstruction shows red tail feathers… but if it was that simple wouldn’t it have been figured out earlier?

  20. #20 Jason S.
    April 13, 2010

    Just to clarify, feathers aren’t scales and the didn’t evolve from scales. Instead, the earliest feathers were more likely hollow tube-like follicles projecting between the scales. In birds and maniraptorian dinosaurs, these follicles support the feather’s barbs.
    The tyrannosauroids had feather-like structure that were intermediate between the simple primitive hollow follicles and feathers with more complex barbs and barbules. The largest species in the late Cretaceous probably shed these sturctures as adults, just as young birds molt their original coat of feathers. These shed feathers didn’t grow back in tyrannosaurs, though, as they do in modern birds, leaving behind naked scales underneath. Any form of additional insulation for a seven-ton predator would have resulted in deadly overheating. If an adult Tyrannosaurus rex ever had plumage it would have been rather sparse and used for some form of display.

    Reference:
    Prum, R.O., & Brush, A.L. 2004. “Which Came First: the Feather or the Bird?” Scientific American Special 14, 72-81.

  21. #21 Matt Martyniuk
    April 13, 2010

    @Cale:
    To determine the color of fossil feathers, you need to study the shape and sometimes chemistry of the microscopic melanosomes preserved inside them. Eyeballing it based on the color of the preserved fossil, as far as I know, usually doesn’t work (this is what was done in the extremely suspect paper on Psittacosaurus color). To determine if the tail feathers were red, you need to use an electron microscope and look for the presence of a certain proportion of ‘russet’ type melanosomes. To be as bright red as shown in that restoration, there would also need to be carotenoid pigments, which animals can’t synthesize, but instead get from eating plants or plant-eating bugs. So, no, I think the perceived color of the fossil and color in the restoration is just a coincidence in this case.

    @ Jerzy:
    Definitely not an artefact of preservation, as many enantiornithines and Confuciusornis specimens at all levels of preservation from poor to exquisite show the same thing, and the ‘gradient’ from undifferentiated to barbed is pretty clear in some cases. The question for me is why do we go from normal veined feathers with barbs in basal long-tailed birds like Archaeopteryx and Jeholornis, to pairs (or double pairs in some enants) of these ribbon-like undifferentiated feathers in the first short-tailed birds, then back to normal arrays of tail feathers in ornithurines. Presumably ornithurines were using their “fan-able” tails for aerodynamic purposes, so that would be one selective pressure, while the ribbon-feathers were mainly for display. But I also wonder if this is another argument for a monophyletic group of confuciusornithids + enantionrithines to the exclusion of ornithuromorphs.

  22. #22 Anonymous
    April 13, 2010

    “No pygostylian has grown a tail”

    What about Sylviornis? Or is that some kind of pseudo-tail?

    “No modern bird has a scaly torso, etc”

    Probably because no modern birds has reached the sizes that most Mesozoic dinosaurs did, to the point where it would make more evolutionary sense to ditch the feathers. Perhaps if there is some Edmontosaurus-sized bird running around in the future, it would lose a good portion of its feathers as well (depending on its environment).

    “It’s not like ratites need feathers, really. And why bare skin for their heads and legs (in the case of ostriches)? Don’t they get sunburned more than a scaly beast would?”

    Probably because the feathers cover most of the areas that would get sunburned, especially with its wings.

    Birds still do have scales today on the feet, but in some cases even those have been lost, like in the passerines.

  23. #23 Cale
    April 13, 2010

    Matt: So then the fact that the fossil looks ‘reddish’ and the reconstruction shows red tail feathers is just a coincidence then?

    All in all I’m just amazed that we’re discovering so much, so recently. Birds are dinosaurs? Hell Yeah. I may not ever see a real T-rex, but I can scoff at all those children’s science books I used to read that insisted the dinosaurs were gone for good. Wonders never cease.

  24. #24 CS Shelton
    April 14, 2010

    Thanks for the information about scales vs. feathers! That being the case, it does seem possible tyrannosaur chicks had down (not necessarily likely, but the hypothesis makes more sense to me now). Also, it seems probable that some slower, smaller dinosaurs had combinations of scales and feathers like an armadillo’s (totally unrelated) configuration. Curse the vagaries of time and geology for not leaving us more / better fossils! I wanna see it all!

    Thanks also for the info on the tail-having pygostylian. Never heard of it! Neat! In other things, I would think an ostrich’s head and neck would be still be vulnerable to sunburn, and I still find it weird no modern bird has scales outside the feet and legs. But maybe I’m wrong about that too.

    Does anyone know of a modern bird with scales anywhere on the body other than the feet & legs? I imagine some might have scales on their faces, but have yet to see an example. Thanks again for the answers, y’all.
    -

  25. #25 CS Shelton
    April 14, 2010

    Ooh, and follow-up thought: Sylviornithidae were galliforms, which is one of the more old school divisions of neornithes. Neoaves probably diverged from them before the extinction of the other dinosaurs, am I right? Maybe basal galliforms had a less developed pygostyle that was more flexible, from an evolutionary standpoint.
    Or maybe I’ll just shut up and let the experts speak now.
    -

  26. #26 David Marjanović
    April 14, 2010

    Where can I find more information on the tail of Sylviornis?

    So, what birds, besides one bird of paradise, have larger plastic-like structures?

    Is this relevant? Is there a reason to suppose that all of feather diversity is present in Neornithes?

    I guess this is more an artifact of poor preservation – details being invisible.

    Completely impossible. Feathers are never preserved like that, especially not the other feathers on the very same specimens.

  27. #27 Darren Naish
    April 14, 2010

    On feathers: it seems that feathers are evolutionary novelties (to steal Alan Brush’s term), and not derived from scales. If you accept the Prum & Brush model – a similar one was proposed a few years earlier by Peter Griffiths (2000) – feathers started life as hair-like filaments.

    Rectrices (comment 21): the absence of rectrices in confuciusornithids is weird, but it should be regarded as an autapomorphy, given that non-avian maniraptorans, archaeopterygids and Jeholornis have them (all of which are ‘more stem-ward’ than confuciusornithids), as do enantiornithines (Shanweiniao has them) and stem-ornithuromorphans (all more ‘crown-ward’). Neornithines show us that the rectricial fan can be lost relatively easily (palaeognaths must have lost it, independently, on several occasions, and grebes lack it).

    Sylviornis: apparently it does have a particularly long tail, but this is because the number of free vertebrae was high, not because the pygostyle was freaky. I don’t know how many free caudals it has, but many other neornithines already have as many as 7. The data might be in Mourer-Chauviré & Balouet (2005) – I haven’t seen this (several other papers from the same volume are available online, but not this one).

    Refs – -

    Griffiths, P. J. 2000. The evolution of feathers from dinosaur hair. Gaia 15, 399-403.

    Mourer-Chauviré, C. & Balouet, J. C. 2005. Description of the skull of the genus Sylviornis Poplin, 1980 (Aves, Galliformes, Sylviornithidae new family), a giant extinct bird from the Holocene of New Caledonia. In Alcover, J. A. & Bover, P. (eds) Proceedings of the International Symposium “Insular Vertebrate Evolution: the Palaeontological Approach”, Monografies de la Societat d’Història Natural de les Balears 12, 205-118.

  28. #28 Anonymous
    April 14, 2010

    You know, it would be nice to see a Tet Zoo article on Sylviornis. Sylviornis is yet another weird species which has most of the information on it “locked away” in the technical literature, to paraphrase Darren. Which is sad because its so odd, what with the unfused clavicles, dinosaur-like body, and freaky tail. And it lived alongside some of the mekosuchine crocodiles and meiolanid turtles. New Calidonia in the Holocene was almost like a real Lost World or Jurassic Park!

  29. #29 Craig York
    April 14, 2010

    The original probably looked nothing like it, but the
    reconstruction reminds me of the scissor-tailed flycatcher,
    which we see very occasionaly her in central Texas.

  30. #30 Jerzy
    April 14, 2010

    @David Marjanovic
    Thanks. I wonder how are these structures formed. Wanes fail to separate during development?

    @Darren
    I would very much like to see any genetic evidence on feather and scale formation in chicken (most likely subject) to show that they are formed using different genes (that is, feathers could evolve from zero, not from scales). Sounds anti-intuitive for me.

    However, this is my pet idea that down coat of modern chicks is homologous of dinosaur protofeathers.

  31. #31 cale
    April 14, 2010

    It occurs to me that certain birds such as ornamental pigeons, ptarmigans and some grouse, and a few breeds of chickens, have a feather/scale combo on their legs. The feathers seem to sprout out from in between the scales. This might be something to consider regarding downy tyrannosaur chicks, and where ‘scales’ end and ‘feathers’ begin.

  32. #32 Jerzy
    April 14, 2010

    This Sylviornis – are there good reasons, besides convenience, to name it galliform? Or avialan? Last relic non-avian dinosaur would be pretty cool. ;-)

  33. #33 CS Shelton
    April 14, 2010

    Jerzy- I had the same thought, but I’m guessing the scientists got that one right. According to wikipedia, it was initially thought to be a megapode, but further analysis puts it in galliformes. When close scrutiny contradicts the initial analysis, I’d think it’s for good reason. But all I can do is guess, because I don’t have the technical literature mentioned at 28. Or a degree in zoology and years of practice.
    Feathered dinosaurs are in my top ten favorite things in life. About an hour ago, some Koreans were laughing at me because I was staring at a red-shafted northern flicker on a telephone pole for minutes on end. I can’t help it!
    -

  34. #34 Dartian
    April 15, 2010

    CS Shelton:

    According to wikipedia, it was initially thought to be a megapode, but further analysis puts it in galliformes.

    Megapodes are galliforms too, so Sylviornis has been in Galliformes all along (or at least since it was realised that its original identification as a ratite was a mistake).

  35. #35 Darren Naish
    April 15, 2010

    It does seem that Sylviornis is a megapode, and hence a galliform (the biggest one ever: estimated mass = 40 kg), but Poplin originally described it as a ratite (mostly because of its size) and a few other authors (like Storrs Olson) later thought that its true affinites couldn’t be determined. I’m highly intrigued by the fact that some websites say that it would have looked like an oviraptorosaur (and there’s that weird, gastornithid-like reconstruction produced by Eric Alibert). Point taken – I will definitely cover it here some time.

  36. #36 David Marjanović
    April 15, 2010

    I wonder how are these structures formed. [V]anes fail to separate during development?

    I suppose so.

    Point taken – I will definitely cover it here some time.

    :-) :-) :-)

  37. #37 CS Shelton
    April 15, 2010

    Oops, I meant ratite, not megapode. I was back and forth between windows and whatnot. And stupid. Word.

  38. #38 Matt Martyniuk
    April 15, 2010

    @Darren:
    I don’t have the Shanweiniao paper on this computer, but I could have sworn the “ornithuromorph-like tail fan” the authors talk about is simply an array of 4-8 strap-tail feathers (as opposed to the usual 2)? Am I remembering incorrectly and those are actually regular rachided & barbed retrices?

    By the way is it retrices or rectrices? I’ve seen it both ways in the lit.

  39. #39 Darren Naish
    April 16, 2010

    Matt (comment 38): it’s rectrix and rectrices.

    On Shanweiniao, O’Connor et al. (2009) state: “… the rachi of Shanweiniao are closely arranged forming a continuous surface indicating that this tail had the potential to act as an airfoil and generate lift. Whether the function of the tail in Shanweiniao was aerodynamic or for display is unclear given the incomplete preservation of the holotype, however the presence of this morphology among enantiornithines reveals the possibility that some members of the clade had evolved this aerodynamic specialization” (p. 196). They go on to discuss the possible link between presence of a pygostyle and presence of rectricial bulbs and a fan-shaped rectricial array.

    Ref – -

    O’Connor, J. K., Xuri Wang, Chiappe, L. M., Chunling Gao, Qingjin Meng, Xiaodong Cheng & Jinyuan Liu. 2009. Phylogenetic support for a specialized clade of Cretaceous enantiornithine birds with information from a new species. Journal of Vertebrate Paleontology 29, 188-204.

  40. #40 Matt Martyniuk
    April 16, 2010

    Thanks Darren. I’m looking at the paper now, and I think what have me that impression is the appearance of the rectrices in the photos. They definitely have rachides but the edges look very smooth, rather than barbed. Maybe that’s just preservation or bad quality photos, but they look a lot like the tail feathers of Epidexipteryx (which also has a “fan” of four rachided though otherwise strap-like rectrices but I don’t think anyone’s suggested a rectrical bulb).

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