Tuesday, September 8, 2009

Misadventures in prehistoric animal reconstructions - The many faces of the Desmostylia I:


This is Desumon, a cartoon desmostylian that was created by a natural history museum in Japan to help introduce the Desmostylia to the public. Desmostylians are very popular in Japan, which is just another sign of their cultural advancement, in my opinion. I mean, there has to be a correlation between the quality of their science and math education and the preponderance of desmostylians in popular culture.

In my anticipation of seeing what marvelous work comes from an illustration by Carl Buell of a new desmostylian I am working on, I thought it would be fun to have a romp through the strange history of the reconstruction of desmostylians. What follows are simply those images I have on my computer at present, although I'll try to make sure and get some of the older images (including ones that compare desmostylians with multituberculates) scanned for future posts. In general, I have several future posts planned to explore the history of the ways people have reconstructed aquatic amniotes. It is not only illustrative of how our perceptions of those animals have changed over time, but also how we approach reconstructions from a scientific standpoint and why so many paleoartists these days are also such excellent anatomists.

Enough blabbing, here are some Desmostylia!



To start, it is a good idea to present a skeleton to get an idea of what we're working with. This is a nice generalized reconstruction of a desmostylian skeleton. Aside from some large feet, funny angles in their ankles, and slightly short limbs, they are a fairly mundane large mammalian herbivore shape -think Anrsinoitherium or Coryphodon (also animals considered semiaquatic - see future posts for critiques of that!)

But, partly because they have these wide, thick sternebrae and short limbs, just how close to the ground they were has been debated.

Most of all, it is because of the finds of the Utanobori Desmostylus skeletons (such as Utanobori I), and the way they were preserved with their limbs sprawled out, some paleontologists have interpreted the Desmostylia as having a "herpetiform" posture, with limbs sprawled laterally like what is seen in most modern squamates. The debate over this matter became even a series of papers, back and forth between Norihisa Inuzuka and L. Beverly Halstead.

So, many of the following reconstructions are not only coming from an attempt to reconstruct an animal that spends much of its time in the water, but also a very specific interpretation of their limb posture. This is not the normal way in which most people would reconstruct mammalian limbs, which is why I think some of them look a little awkward.

Rather than blab on and on, I'll let them speak for themselves. The pics are in order of most aquatic/herpetiform to most terrestrial.... I'll let you decide what you think is most realistic. For fun, I've numbered them so you can refer to them in comments. Please, tell me which ones you think are most realistic, or most of what your opinion of Desmostylia has been thus far.
Have fun!





1
2
345
6
7
8
9
10

This is just a start, I'll try to have more on this soon!

12 comments:

  1. I rather like the way #7 looks.

    I've noticed a lot of reconstructions have the hind legs both splayed and angled posteriorly rather oddly (such as #9). Is there anything in the pelvis to justify this? Although admittedly, I have a dog that often splays his legs that way when he's lying down.

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  2. It is mostly a feature of the ankle that has caused various people to puzzle over this. Daryl Domning pretty conclusively ended that debate with his paper of 2001 on a comparative study of the torsion of the ankle being found in several other terrestrial mammals, including chalicotheres.

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  3. very interesting post... I saw a Paleoparadoxia tabatai today (obviously not a live one, the mounted skeleton and a reconstructed model) at the Natural History Museum, London. The reconstruction looks a lot like #8 above, especially with the hippopotamus-like head and splayed ankles. Oddly enough though, only the ankles are splayed, and not the wrists, and the forelimbs are less angled, giving the model a strongly-sloping back. I want to do my own reconstruction, but can't decide which image to use as a base... they're all so radically different. Perhaps I'll just put flesh and skin on the skeleton and see how that looks!

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  4. You're just doing this to get me off my ass and make me start drawing aren't you Brian. Okay... I'll do some work on it this weekend... ;-)>

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  5. Hey Carl, I didn't mean it in that way, I was just excited lately about your reconstruction sketch and had been planning this post for a while. Your great sketch just got me moving on it.
    No pressure, just excitement!

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  6. Great post, Brian! I greatly look forward to reading the rest of the series!

    And you've gotta love Japanese pop-culture! :)

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  7. What were the ancestors of desmostylians? Indo-pakistanese ANthracobunids?

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  8. I love the cartoon Desumon - although my girlfriend noted, he looks just like a hippo - which, with desmostylians, is a pretty hard analogy to get away from, I'll admit.

    I'm looking forward to your coverage of Domning's 2001 paper - also a very awkward looking reconstruction of desmostylians, but decidedly more likely. I haven't read that paper in several years; perhaps I should flip through it again sometime. By the way... the holotype dentary of Paleoparadoxia repenningi is GIGANTIC... I've only seen that and a couple other bones at UCMP; I'm not sure where the rest of the skeleton is.

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  9. To Simoes Lopes - the putative ancestors of desmostylians are considered to be anthracobunids, though which ones and where they come from is another mystery. Some consider them relatives of primitive Proboscidea, or an earlier offshoot of the Paenungulata. We'll just have to wait and see for more material, more analyses....

    To Bobby - I'll try to get the post about the current status of desmostylian reconstructions soon. A student in Japan is soon to have a paper out in J Morphology about posture in desmostylians that will be an excellent study of posture in mammals in general. You can keep an eye out for it, though I think that when his paper comes out I will try to highlight it in my next post, along with comments on Domning 2001 and Inuzuka's older papers arguing with Halstead.

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  10. Hi! You've got a very interesating blog here! Could you let me know who's the artist who made the last two images that you posted i this article? Of Desmostylia
    I'd really appreciate it!

    Greco westermann

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  11. Golly guys… I went down to the Stanford Linear Accelerator and someone had just thrown a rubber hippo into and old aquarium and called it a day. Looks like a hippo to me.

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  12. I did this model based on some pics in here.

    https://www.facebook.com/photo.php?fbid=10200819721908586&set=gm.146385938899804&type=1&theater

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