My most depressing paper

October 6, 2015

I have a new preprint up at PeerJ (Taylor 2015), and have also submitted it simultaneously for peer review. In a sense, it’s not a paper I am happy about, as its title explains: “Almost all known sauropod necks are incomplete and distorted“.

Taylor 2015: Figure 10. Manipulation of consecutive sauropod vertebrae by hand. Cervicals 2 and 3 of Giraffatitan brancai lectotype MB.R.2181 (formerly HMN SI). I attempted to articulate these two vertebrae, and empirically determine the feasible range of motion. Due to subtle distortion of the zygapophyses of these vertebrae, it was not possible to articulate C2 in a more extended position relative to C3 than shown here. Photograph by Mathew J. Wedel.

Taylor 2015: Figure 10. Manipulation of consecutive sauropod vertebrae by hand. Cervicals 2 and 3 of Giraffatitan brancai lectotype MB.R.2181 (formerly HMN SI). I attempted to articulate these two vertebrae, and empirically determine the feasible range of motion. Due to subtle distortion of the zygapophyses of these vertebrae, it was not possible to articulate C2 in a more extended position relative to C3 than shown here. Photograph by Mathew J. Wedel.

This paper has been a while coming, and much of the content will be familiar to long-time readers, as quite a bit of it is derived from three SV-POW! posts: How long was the neck of Diplodocus? (2011), Measuring the elongation of vertebrae (2013) and The Field Museum’s photo-archives tumblr, featuring: airbrushing dorsals (2014). It also uses the first half of my 2011 SVPCA talk, Sauropod necks: how much do we really know? (and the second half became the seed that grew into our 2013 neck-cartilage paper.)

So in one sense, publishing this is a bit of a mopping up exercise. But it’s also more than that, because I think it’s important to get all these observations (and the relevant literature review) down all in one place, to help us recognise just how serious the problem is. There are, to a first approximation, no complete sauropod necks in the published literature.  And the vertebrae of the necks we do have are crushed to the point where trying to articulate them is close to meaningless.

Taylor 2015: Figure 8. Cervical vertebrae 4 (left) and 6 (right) of Giraffatitan brancai lectotype MB.R.2180 (previously HMN SI), in posterior view. Note the dramatically different aspect ratios of their cotyles, indicating that extensive and unpredictable crushing has taken place. Photographs by author.

Taylor 2015: Figure 8. Cervical vertebrae 4 (left) and 6 (right) of Giraffatitan brancai lectotype MB.R.2180 (formerly HMN SI), in posterior view. Note the dramatically different aspect ratios of their cotyles, indicating that extensive and unpredictable crushing has taken place. Photographs by the author.

I’m not happy about this. But I think it’s important to face the reality and be honest with ourselves about how much we can really know about sauropod necks. There’s a lot we can do in a qualitative way, but most quantitative results are going to be swamped in supposition and error.

Reference

Taylor, Michael P. 2015. Almost all known sauropod necks are incomplete and distorted. PeerJ Preprints 3:e1767. doi:10.7287/peerj.preprints.1418v1

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13 Responses to “My most depressing paper”

  1. Daniel Vidal Says:

    I have a couple of questions for you Mike:

    1) What about Shunosaurus? There are supposedly a handful of preserved specimens. It would be a great candidate to look for well preserved necks. Have we got any information beyond the publications (ie photographs or drawings of the material not figured in the chinese publications)?

    2) What are your thoughts on digital retrodeformation? As far as I have been experimenting with it, it is yielding very nice results.

    And, indeed, fossildiagenesis is a caveat when studying biomechanics and ranges of motion in fossil taxa, and it has not been taken into account as much as it should have IMO.

  2. Mike Taylor Says:

    Hi, David, good to hear from you. And thanks for your interest!

    I briefly discuss Shunosaurus in the preprint, on page 3:

    Shunosaurus lii was described by Dong et al. (1983), based on a specimen, IVPP V.9065, from which only five cervicals are known, all of them poorly preserved. However, Zhang et al. (1984) indicates that multiple additional specimens are known, and their figure 1 is a quarry map showing a very complete specimen ZDM T5401 with all vertebrae from cervical 2 to caudal 7 in articulation. Zhang (1988: figure 2) illustrated a different complete specimen ZDM T5402 as excavated. Chatterjee and Zheng (2002) also confirmed that Shunosaurus is known from several complete skeletons.

    And then at the bottom of that page:

    As best we can tell, only one sauropod – Shunosaurus – is known from more than a single complete neck; and those multiple specimens have not been described. So while in theory it might be possible to determine whether there is a bimodal distribution in the length of Shunosaurus lii necks, the data doesn’t exist to do this work.

    On retrodeformation: I don’t know much about it, so anything I say should be taken with a pinch of salt. My big question would be, using MB.R.2810 as your example: how would you know to deform C4 by lateral expansion or C6 by lateral compression if you only had one of them?

  3. Daniel Vidal Says:

    I am amazed that in 30 years no more pictures of Shunosaurus fossils have surfaced so we can have a better idea on how it looked.

    About retrodeformation, it is indeed tricky. With isolated elements you really can’t do much unless the deformation affects equally the bone in a single axis (which is not usually, if ever, the case), in which you would restore the symmetry of the element.

    In the case you bring, having more elements from the same individual (as is the case) is helpful. The amount of distorted symmetry in C6 is greater than is in C4 (the cpol for example), so my bet would be using C4 as a model in order to restore C6.

    A complete and thorough retrodeformation protocol however should, in my opinion, to take into account all of the most probable restorations and contrast the range of motion results obtained from each restoration. If they are compatible, hurray!, the results should be more likely to yield meaningful results about the undistorted neck. If not, the results should be discussed as walking on ice and subject to change when better preserved remains are found.

  4. Stefan Reiss Says:

    I think, Amargasaurus cazaui could be represent an interesting Special case because the long neural spines of the cervicals make a correct Interpretation of neck motions more difficult. In the first description of the species Salgado & Bonaparte (1991) wrote: “22 articulated presacral vertebrae and articulated with the cranium and sacrum, relatively complete and associated with some ribs;”. 13 of these vertebrae were assumed to be cervicals. However, Carabajal et al. (2014) noted distortions of the neural spines of some cervicals in Amargasaurus cazaui. I think, one can assume further distortions of other parts of the vertebrae.

    Mike: Great work! I hope the final Version will be soon publish. :)


  5. Hi Mike,

    I’m following this superb blog for a while now but I haven’t comented so far.

    There is one more described, complete/nearly complete neck of a sauropod:
    The Kaatedocus siberi holotpye SMA 0004 was described by Emanuel Tschopp and Octávio Mateus in 2013. The neck is complete (from proatlas to C14) but one proatlas and the axis weren’t found articulated and might belong to an other specimen.

    There are more complete sauropod(-necks) in the Sauriermuseum Aathal but they aren’t described (yet?). I’m refering to the Galeamopus sp. SMA 0011 (neck complete but (lateraly?) compressed) and the Camerasaurus sp. SMA 0002 (neck completely preserved, in three dimensions, and articulated).

    Reference: Tschopp E, Mateus O. 2013. The skull and neck of a new flagellicaudatan sauropod from the Morrison Formation and its implication for the evolution and ontogeny of diplodocid dinosaurs. Journal of Systematic Palaeontology 11:853–888. doi: 10.1080/14772019.2012.746589

  6. LeeB Says:

    Well taking this on board it means that anyone who does win the lottery and finds a sauropod with an articulated neck should make sure they do a really good description of it in it’s entirety.


  7. Are the cervicals in the type specimen of Camarasaurus lewisi articulated? The original description implies as much but doesn’t actually say. Other than that, Camarasaurus sp. SMA 0002 seems to have an articulated and complete cervical series as well. Euhelopus also apparently has everything but the atlas articlated.

  8. Mike Taylor Says:

    Oliver Demuth rightly reminds me that the neck of the diplodocine Kaatedocus (Tschopp and Mateus 2013) is also essentially complete and very nicely preserved. Given that I have cited this paper and even reproduced some of its supplementary figures in my own work (e.g. Taylor and Wedel 2013b) it’s astonishing to me that I overlooked it. Thanks to Oliver for putting me straight!


  9. […] I’m a moron again. In the new preprint that I just published, I briefly discussed the six species of sauropod for which complete necks are known — […]


  10. […] I posted my preprint “Almost all known sauropod necks are incomplete and distorted” and asked in […]


  11. When it comes to the different widths of the posterior face of cervical centra relative to their heights, have you considered development of bone between functional regions of the neck incurring differential strain between them? I’d imagine the size or thickness of the cuffs that form the centrum faces should differ somewhat between regions that exhibit different strain regimes, which of course is useful when considering neck attitude and range of motion.

  12. Mike Taylor Says:

    Modern animals don’t seem to vary the proportions of the articular surfaces of adjacent or near-adjacent vertebra — see the illustrations in the preprint, which I included precisely to make this point. Also: C13 and C14 of Diplodocus are in the same functional region :-)


  13. […] my recent preprint on the incompleteness and distortion of sauropod neck specimens, I discuss three well-known sauropod specimens in detail, and show that they are not as well known […]


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