SuperCroc’s sidekick

June 15, 2008

Paul Sereno’s Project Exploration has a traveling exhibit called The Science of SuperCroc, which I recently visited at my old stomping grounds, the Oklahoma Museum of Natural History. The exhibit focuses on Sarcosuchus, the improbably large and possibly Kryptonian crocodilian from the Cretaceous of Niger, but it also includes nice mounted skeletons of the spinosaur Suchomimus and–relevant to our purposes here–the just plain improbable sauropod Nigersaurus.

At least one of my co-bloggers probably thinks I should stop pandering to the crowds with my mounted skeleton posts and get back to hardcore vertebral anatomy. After all, that’s the raison d’etre of SV-POW!, and I have been falling behind a little lately. Still, I’m going to risk the Wrath of Mike and go ahead and post about the mounted Nigersaurus skeleton, and why you should definitely go see it if you get the chance.

Here are my reasons for doing so:

1. It is a demonstrated scientific fact, as rock-solid as the value of c or the proposition that the Amazon basin is damp, that Nigersaurus is Damn Weird. In a clade of little-known weirdos (Rebbachisauridae), it promises to be an exceedingly well-known ultra-weirdo, thanks to (1) the large number of skeletons that have been discovered, including both juveniles and adults, and (2) the sheer vastness of its weirdness, which you can sample immediately and without charge courtesy of Sereno et al. (2007) and the kind offices of the Public Library of Science (translation: free paper here).

2. Although Nigersaurus was named in 1999 and has been the subject of three peer-reviewed publications, not much of the skeleton has been figured to date. So the opportunity to see the whole critter up close is pretty remarkable. If sauropods were heavy metal, the traveling Nigersaurus mount would be an evening backstage getting high with Led Zeppelin, circa 1973. Certainly if you work on sauropods, the morphology of Nigersaurus will make you think that someone has been under the influence of powerful illicit substances, and that someone is Mother Nature (or Gaia, or the overused/sexist/quasi-pantheistic biosphere personification of your choice).

3. It’s a really nice mount. It’s fiberglass, but the quality of the casts is first rate. I have seen a lot of traveling skeletons that looked like they were made out of Play-Doh by speed-sculpting chimps, but the mounts in the SuperCroc exhibit are all well cast, gracefully mounted, and nicely displayed, by which I mean that you can get up close to them and walk most or all of the way around them, which is my major pet peeve about mounted skeletons: I want to be able to see them from any angle, or at least many angles. SuperCroc delivers.

4. The exhibit includes a lot of display cases that explain the detailed anatomy of the beasts. For Nigersaurus alone, there were cases on vertebral pneumaticity (yay!), the vertebrae themselves (real bones), the detailed anatomy of the jaws (real bones, from the holotype!), the head and neck skeleton plus life sculpture (shown at the top), adult and baby femora (real bones), probable feeding ecology, and maybe one or two others I can’t remember, plus a giant wall hanging of the full-color life restoration painting that came out with the 2007 paper.

So if you get a chance to see SuperCroc, it’s worth it just for the sauropod.

I’ll have tons more to say about the Nigersaurus vertebrae in future posts, but the short version is that they are small and unbelievably delicate. Mike and I always characterize Camarasaurus vertebrae as coarse, fat, and kind of ugly; the vertebrae of Nigersaurus are the aesthetic opposite. They look like they might have been constructed out of toothpicks and white glue. And they are crazy pneumatic. In one of his essays, outdoor humorist Patrick F. McManus characterized a poorly-maintained country bridge as consisting mostly of holes that were elevated and loosely defined by a few rotting beams. Similarly, the skull and cervical vertebrae of Nigersaurus seem to be mostly holes, with just enough bone around them to suggest the form of a sauropod. One more half-baked comparison: the mounted Nigersaurus looks like the skeleton of a skeleton, at least in the craniocervical region.

I want to make a final point that is not really about vertebrae. As you can see in the photo above, and to beat a dead thunder-lizard, sauropods had erect limbs, compact feet, and deep, slab-sided bodies. You don’t have to be a zoologist to see that this is a body-form made for roaming the land, not for bobbing around slurping up pond scum. That’s not to say that sauropods didn’t go into the water. They probably did so all the time. Elephants do, almost every chance they get. Heck, elephants may even be descended from aquatic ancestors. But no one would characterize elephants as aquatic or even semi-aquatic. Sauropods weren’t elephants, and they weren’t giraffes, and facile comparisons of sauropods to big mammals have probably done more harm than good to sauropod paleobiology. But sauropods weren’t hippos or manatees, either, despite decades of ecological characterization as such. The Aquatic Sauropod era officially ended the same year I was born, so you may rightly wonder why I am tilting at this particular windmill. It’s because ideas are seductive, and sometimes we allow them to make us blind to the obvious. I don’t know of any way to fight that tendency other than to keep asking questions.

And I don’t know of a sauropod that is more likely to provoke questions than Nigersaurus. Go see it if you can.

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18 Responses to “SuperCroc’s sidekick”

  1. Adam Pritchard Says:

    That is an absolutely beautiful mount. Does anyone know if Nigersaurus is still on display at the National Geographic Center in Washington?

  2. Darren Naish Says:

    Like your last point, my comment here is kind of tangential to the main theme of your post, but what the hell: may I be only the latest in a long list to say that, truly, we here at SV-POW! have truly created what is without doubt the most amazing thing on the entire internet. I thank you.

  3. Zach Miller Says:

    Damn my Alaskan commute! I would LOVE to see those skeletons! Nigersaurus may be my favorite sauropod. Like you say, aside from its bizarre skull and lawnmowing dentition, the bugger’s bones are transparantly thin! It must have been a ridiculously lighweight sauropod.

  4. Graham King Says:

    I love Nigersaurus. It’s so freaky it satisfies even me. Well, no. Not really… it just whets my appetite for the even-freakier next thing to come along (something always does.)

    May I here introduce a ridiculous idea which I hope that no-one else has thought of: that sauropod pneumatic cavities were not pneumatic at all, being filled with not air, but VACUUM… and were actively maintained so (by hitherto-unsuspected ingenuities of biology), as the logical endpoint of all weight-reducing measures.

    Also pterosaurs, likewise too. Probably.

    So, Palaeontologists all, be on the lookout for bones that show signs of having imploded under stress.

    ;-D

  5. Nathan Myers Says:

    Graham was close: the spaces held not vacuum, but microbially produced hydrogen. Nigersaurus bobbed along, dabbing at the ground — or wavetops — with the tips of its toes. (Cue “Just A-drifting”, from the Disney version of Grahame’s Reluctant Dragon.) Its odd dentition wasn’t particularly for feeding, it was mainly used to clamp a wad of grass to keep from blowing away when the breeze freshened.

  6. Matt Wedel Says:

    May I here introduce a ridiculous idea which I hope that no-one else has thought of: that sauropod pneumatic cavities were not pneumatic at all, being filled with not air, but VACUUM… and were actively maintained so (by hitherto-unsuspected ingenuities of biology), as the logical endpoint of all weight-reducing measures.

    Actually, that’s a pretty darned interesting question: could biological ingenuity produce a vacuum-filled (emptied?) cavity? It would have to be lined with something tough and avascular, otherwise the adjacent tissues would just weep fluids into it. Possibly some kind of rete system could be used to scavenge most of the air in the cavity, and then a hinged door could slam over the gas-uptake mechanism, after which the vacuum cavity would be sealed behind walls of chitin or something.

    Your vacuum would have a lower density than Nathan’s hydrogen-filled cavity, so your sauropod would be even more buoyant than his. His would be prone to fiery explosions, and, as you indicate, yours would be vulnerable to non-fiery implosions.

    Given that several different groups of animals have evolved gas-filled floats for buoyancy in water (the float of a Portuguese man-o-war, cuttlebone in cuttlefish, etc.), it has always seemed odd to me that no animal has evolved a lighter-than-air float for buoyancy in air. For example, dry air at sea level is almost twice as dense (1.3 kg/m^3) as methane (0.717 kg/m^3). So if some wee beastie could harness its own farts, it could potentially sail away into the ocean of air. Who knows what niches might be exploited by the diversification of these flying fart-bags, which would automatically be unpalatable to all but the most coprophagic of airborne predators?

    That’s right, folks. Come for the sauropod vertebrae, stay for Die Flederflatus.

  7. Nathan Myers Says:

    If I might be permitted to intrude a gross physical fact, a vessel capable of holding back a full atmosphere would need to be way, way stronger than those paper-thin bones. Hydrogen at one atmosphere would be only slightly heavier than true vacuum, place no load on the poor bones and be way lighter than methane. It would tend to slow leakage, so need to be continuously replenished.

    Explosion would be a danger only in lightning storms, or if N. learned learned to ignite its flatus, and even then only with an appropriate admixture of oxygen or peroxide. (The flames you see on Hindenburg were from the kerosene fuel, scattered into air and ignited by an on-board bomb. Most of the hydrogen went straight up without burning.)

    I imagine inland seas of carbon dioxide, with balloon-like plants floating on them at the carbon dioxide – air interface. N. floated there too, poking its head up high to breathe.

    Seriously, I’m curious about those enormous orbits. The life reconstruction shows tiny eyes in them. Why grow enormous orbits for tiny eyes?


  8. I think we won’t be able to see this exhibition here in Spain… What a pity!

  9. Mike from Ottawa Says:

    “the mounted Nigersaurus looks like the skeleton of a skeleton”

    I like that turn of phrase. It does capture the sense of the thing being nothing but a few struts.

    Sauropods are much more interesting walking around in their bones and nothing else.

  10. Adam Yates Says:

    MW asks
    Actually, that’s a pretty darned interesting question: could biological ingenuity produce a vacuum-filled (emptied?) cavity?

    The world is a wonderfull place. I give you Utricularia, the bladderworts, which are plants that create little vacuums in special bladders, not for the purpose of bouancy but for the purpose of capturing prey.

  11. Graham King Says:

    Mike from Ottawa says:

    “the mounted Nigersaurus looks like the skeleton of a skeleton” [quoting Matt]

    I like that turn of phrase.

    Me too!

    May I suggest Origamisaurus as a suitable genus name for a yet-to-be-discovered dinosaur… whose remains will look like only a folded-paper model of the skeleton of a skeleton? And for the next one, even lighter-weight than that… Diagrammosaurus?

    And attempting a synthesis of the ideas here re Nigersaurus (ultra-lightweight, hydrogeno?pneumatic, grazing dentition and with conspicuously-large orbits):
    It was a large-eyed nocturnal cropper of low-level vegetation, bobbing lightly along barely impacting the substrate… and so ideally suited to keeping lawns and golf-courses trimmed, without leaving footprints.

    If luminous-bellied and prettily coloured, it would make a handy, visually-appealing and nvironmentally-friendly tidier-up of food debris for outdoor parties and pop concerts.

  12. Randy Says:

    Nice McManus reference! He is a completely underrated humor essayist. Which reminds me – I haven’t read any of his books in a while. Could be a good source dissertation procrastination.

  13. Nathan Myers Says:

    Just for completeness, that went…

    Just a-Drifting

    Just a-drifting o’er the leaves like a dewdrop,
    fancy-free, playing with the gentle breeze
    And romping with the bumble-bees…-es,
    oh how fun, joy never ceases…
    Just a-drifting

    Prancing, dancing to and fro,
    not too fast, not too slow
    Where the early birds are seeking,
    early worms are shyly peeking,
    hear the night owls softly squeaking…
    Just a-drifting.

  14. Zach Miller Says:

    I’m reading the newest McManus collection right now (“Kerplunk!”). He’s still got it, although my only criticism of his writings (now as ever) is that he spends WAY too much time writing about being a kid. Now, my favorite all-time McManus story is from that mold (“My First Deer”), but I think he’s at his best when writing about his modern hunting and fishing adventures.


  15. [...] deficiency is not limited to any one working group or country or continent or language, either. Nigersaurus is known from multiple specimens and has been the subject of three separate peer-reviewed papers [...]


  16. [...] point of the post is not that sauropods had deep, slab-sided bodies. We’ve covered that before. The point is that sauropod torsos are seriously weird. In mammals, the dorsal ribs arch up and [...]

  17. DinoSaur Says:

    You know, it’s nice to have a sauropod in Niger that was on top of the favorite prey lists, since it was a bit of a lightweight rebbach, compared to things like Rebbachisaurus itself. Then again,Nigersaurus does seem to be the best-known rebbachisaur, thanks to its almost undignified, disgusting looking skull, and also living with Sarchosuchus, suchomimus, Eocarcharia and Kryptops (sorry, but anatosuchus is there too, so maybe its size prevented me). Oh, and by the way, if Nigersaurus had such a hang-dog skull, perhaps Rebbachisaurus, Limaysaurus, Cathartesaura and company had it as well.


  18. [...] and slab-sided, they were unusually deep and slab-sided, more so than in most other tetrapods (see this and this, and for a more pessimistic take, this). This is something that is easy to get wrong; we [...]


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