Welcome Kaatedocus: this is how to illustrate a sauropod

December 20, 2012

A couple of days ago, a paper by Tschopp and Mateus (2012) described and named a new diplodocine from the Morrison Formation, Kaatedocus siberi, based on a beautifully preserved specimen consisting of a complete skull and the first fourteen cervical vertebrae.

Unfortunately, the authors chose to publish their work in the Journal of Systematic Palaeontology, a paywalled journal, which means that most of you reading this will be unable to read the actual paper — at least, not unless you care enough to pay £27 for the privilege.

So you’ll just have to take my word for it when I tell you that it’s a fine, detailed piece of work, weighing in at 36 pages. It features lavish illustrations of the skull, but we won’t trouble you with those. The vertebrae are illustrated rather less comprehensively, though still better than in most papers:

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Tschopp and Matteus (2012: figure 9). A, Photograph and B, drawings of the mid-cervical vertebrae of the holotype of Kaatedocus siberi (SMA 0004). Photograph in lateral view and to scale, CV 8 shown in the drawings is indicated by an asterisk. Drawings of CV 8 (B) in dorsal (1), lateral (2), ventral (3), posterior (4) and anterior (5) views. Scale bars = 4 cm.

It should be immediately apparent from these lateral views that the vertebra are rather Diplodocus-like. But the hot news is that there is a great raft of free supplementary information, including full five-orthogonal-view photos of all fourteen vertebrae!

Here is just one of them, C6, in glorious high resolution (click through for the full awesome):

tjsp_a_746589_sup_30911353

Now, folks, that is how to illustrate a sauropod in 2012! The goal of a good descriptive paper is to be the closest thing possible to a proxy for the specimen itself, and you just can’t do that if you don’t illustrate every element from multiple directions. By getting this so spectacularly right, Tschopp and Matteus have made their paper the best illustrated sauropod descriptions for 91 years. (Yes, I am talking about Osborn and Mook 1921.)

It’s just a shame that all the awe-inspiring illustrations are tucked away in supplementary information rather than in the paper itself. Had the paper been published in a PLOS journal, for example, all the goodness could have been in one place, and it would all have been open access.

Is Kaatedocus valid?

There’s a bit of a fashion these days for drive-by synonymisation of dinosaurs, and sure enough no sooner had Brian Switek written about Kaatedocus for his new National Geographic blog than comments started cropping up arguing (or in some cases just stating) that Kaatedocus is merely Barosaurus.

It’s not. I spent a lot of time with true Barosaurus cervicals at Yale this summer, and those of Kaatedocus are nothing like them. Here is Tschopp and Mateus’s supplementary figure of C14:

tjsp_a_746589_sup_30912152

And here is a posterior vertebra — possibly also C14 — of the Barosaurus holotype YPM 429, in dorsal and right lateral views:

IMG_0441

IMG_0430

Even allowing for a certain amount of post-mortem distortion and “creative” restoration, it should be immediately apparent that (A) Barosaurus is much weirder than most people realise, and (B) Kaatedocus ain’t it.

There may be more of a case to be made that Kaatedocus is Diplodocus — but that’s the point: it there’s a case, then it needs to be actually made, which means a point-by-point response to the diagnostic characters proposed by the authors in their careful, detailed study based on months of work with the actual specimens.

There seems to be an idea abroad at the moment that it’s somehow more conservative or sober or scientific to assume everything is a ontogenomorph of everything else — possibly catalysed by the Horner lab’s ongoing “Toroceratops” initiative and subsequent cavalier treatment of Morrison sauropods — maybe even by the Amphidocobrontowaassea paper. Folks, there is no intrinsic merit in assuming less diversity. Historically, the Victorian sauropod palaeontologists of England did at least as much taxonomic damage by assumptions of synonymy (everything’s Cetiosaurus or Ornithopsiswhatever that is) as they did by raising new taxa. The thing to do is find the hypothesis best supported by evidence, not presupposing that either splitting or lumping is a priori the more virtuous course.

Sermon ends.

Morrison sauropod diversity

As we’ve pointed out a few times in our published work, sauropod diversity in the Kimmeridgian-Tithonian in general, and in the Morrison Formation in particular, was off-the-scale crazy. There’s good evidence for at least a dozen sauropod genera in the Morrison, and more than fifteen species. Kaatedocus extends this record yet further, giving us a picture of an amazing ecosystem positively abundant with numerous species of giant animals bigger than anything alive on land today.

Sometimes you’ll hear people use this observation as a working-backwards piece of evidence that Morrison sauropods are oversplit. Nuh-uh. We have to assess taxonomy on its own grounds, then see what it tells us about ecosystem. As Dave Hone’s new paper affirms (among many others), Mesozoic ecosystem were not like modern ones. We have to resist the insidious temptation to assume that what we would have seen in the Late Jurassic is somehow analogous to what we see today on the Serengeti.

Hutton’s (or Lyell’s) idea that “the present is the key to the past” may be helpful in geology. But despite its roots as a branch of the discipline, the palaeontology we do today is not geology. When we’re thinking about ancient ecosystems, we’re talking about palaeobiology, and in that field the idea that the present is the key to the past is at best unhelpful, at worst positively misleading.

Sermon ends.

But isn’t the Kaatedocus holotype privately owned?

You’ve had two sermons already, I’m sure we can all agree that’s plenty for one blog post. I will return to this subject in a subsequent post.

Sermon doesn’t even get started.

References

Osborn, Henry Fairfield, and Charles C. Mook. 1921. Camarasaurus, Amphicoelias and other sauropods of Cope. Memoirs of the American Museum of Natural History, n.s. 3:247-387, and plates LX-LXXXV.

Tschopp, Emanuel, and Octávio Mateus. 2012. 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. doi:10.1080/14772019.2012.746589

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15 Responses to “Welcome Kaatedocus: this is how to illustrate a sauropod”

  1. Andy Farke Says:

    On the subject of Morrison sauropod diversity, there really is no such thing as a monolithic Morrison fossil assemblage (as you know). . .it spans something like seven million years, so I suspect at least some of the apparent time-averaging as well as geographic effects. But I will admit that even if you do look just at individual quarries, there are quite a few taxa in each!


  2. How do the Kaatedocus cervicals compare to the juvenile Barosaurus cervicals (or at least, alleged juvenile Barosaurus cervicals) at the AMNH?

  3. Mike Taylor Says:

    Andy: yes, of course you’re right that in ecological terms there isn’t really any such thing as “The Morrison”. Not only does it cover several million years of evolution, it also seems to have a distinct faunae in the northern and southern provinces. But, yes, individual quarries contain plenty enough sauropod species to make you go “huh”.

    Tom: I deliberately didn’t comment on the AMNH’s juvenile alleged Barosaurus cervicals because I know that Matt has an iron in that fire, and I wanted to leave the field open for him. I’ll keep quiet on that for now, hoping that he’ll get a chance to chip in soon. (Right now, I believe he’s in the air between California and Oklahoma.)


  4. Got it; thanks! Looking forward to what Matt has to say.

  5. Mike Taylor Says:

    So am I :-)

    On 21 December 2012 16:42, Sauropod Vertebra Picture of the Week

  6. Ralph Chapman Says:

    Highly unsurprising that a paper that Octavio was involved in would be of great quality. Just saying.

  7. LeeB Says:

    It would be interesting to see the Kaatedocus material compared with the cranial material from the Howe quarry mentioned in Michelis dissertation on the taphonomy of the Howe quarry.
    Perhaps this is more Kaatedocus material.

    Also it would be nice to see how it compares with Diplodocus hayi; isn’t this from the northern Morrison also.

    And the diversity of sauropods in the Morrison may compare with that in the upper and lower Shaximiao formation from Sichuan, a lot of Mamenchisaus and Omeisaurus species have been named from there but there seems to be sufficient diversity in their morphology that they may eventually be put in a number of genera.

    LeeB.

  8. Nathan Myers Says:

    Pah. No stereo imaging? What do they take us for, unsophisticates?

    I am going to assume that stereo images were not permitted by the journal, and the authors were obliged to publish just one of each pair.

  9. Matt Wedel Says:

    On the AMNH juvenile Barosaurus verts…

    This is especially confusing because there are two nearly complete, separate series, and both were catalogued as AMNH 7535. The nicer set, which includes a fair amount of cranial material, was put on display next to the life-size juvenile Barosaurus model, and the not-quite-as-nice set (which is still much better than most sauropod necks!) stayed up in collections.

    I am dead certain, from having looked carefully at the big Barosaurus cervicals at Yale, the AMNH, the Carnegie, and BYU, and at more juvenile Barosaurus at BYU, that the not-quite-as-nice set up in collections is Barosaurus, and that the nicer set on display is not Barosaurus. Primarily this is just centrum proportions. Dig out McIntosh (2005), look at photos and measurements of the cervicals, then look at the on-display AMNH juvenile “Barosaurus”–or, indeed, look at Kaatedocus. The mid-cervicals of Barosaurus are MUCH longer and lower-spined than those of either Kaatedocus or AMNH juvenile “Barosaurus” (i.e., the display specimen, not the specimen up in collections–the latter does have crazy-long mid-cervicals that match up perfectly with those of real Barosaurus).

    Could the AMNH juvenile “Barosaurus” (display specimen) be Kaatedocus? Maybe. I haven’t compared them closely yet because (a) Kaatedocus just came out, and (b) I’m travelling for the holidays. But it wouldn’t surprise me.

    Anyway, Kaatedocus is not Barosaurus, and anyone who thinks it is needs to stop armchair quarterbacking and go do some work.

  10. Heteromeles Says:

    You know, I’m really waiting for someone to start comparing sauropods and insects, especially sauropods and ants. Am I alone in getting the impression that the reason we don’t see sauropod-scale mammals is because there are so many phytophagous insects? This plays up the scale in the food web too. Many small animals now are partially or completely insectivorous. If the insect portion of the food web was instead being consumed in bulk by sauropods, one might expect to see not only fewer phytophagous insects, but fewer predators on those insects, and hence, fewer small vertebrates. Jurassic insects might instead have been concentrated on the decomposition part of the ecosystem (to put it less elegantly, sauropod dung), which contains a lot less energy, and hence supports less diversity. Entomologists can actually study this, by looking at the position of phytophagous insects within the insect clade, and by determining whether they evolved from decomposer ancestors.

    The other interesting candidate group are the wood-rotting fungi, which didn’t really come into their own until well in the Mesozoic. I know that hadrosaurs supposedly consumed rotten logs, but I also wonder where all that wood went before there were lignin-consuming fungi around to eat it. Sauropods again?

  11. Andy Hall Says:

    The skull and neck of a new flagellicaudatan sauropod from the Morrison Formation and its implication for the evolution and ontogeny of diplodocid dinosaurs by E. Tschopp and O. Mateus is now free to read at http://ow.ly/gMzti

  12. Mike Taylor Says:

    Thanks, Andy, this is great news! Are you able to tell us why this paper is free to read? Also, what are the terms? Is it now open-access (e.g. CC BY)? I can’t find that information on the page.

  13. Andy Hall Says:

    The article was due to be free for a limited time as news of the article was distributed. It is now free until the end of March.

  14. Mike Taylor Says:

    OK, thanks for clarifying. BTW., it would be good (for both the publisher and readers) to put an explicit statement on such temporarily-free pages, so we all know what we can and can’t do with the material.


  15. […] the vertebrae to the level that we’d hope to see today — certainly nothing like the glorious job Tschopp and Matteus (2012) did on Kaatedocus. As a result, all you get is smallish black-and-white drawings like this one, of C5 of MB.R.2180 […]


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