September 25, 2015
On the morning of Tuesday 1st December, on SVPCA day 1, I gave my talk about apatosaur neck combat. In one of the afternoon sessions, I sat next to Bob Nicholls, and found myself thinking how awesome it would be if he sketched some apato-combat.
But I didn’t want to come right out and say “Hey, Bob, how ’bout you spontaneously illustrate our palaeobiological hypothesis?” So instead I used a tactic that Fiona often uses when she wants me to do something: she starts to do it herself, badly, and waits for me to take over. (This is often how I find myself cooking in the evenings.) In the same spirit, sat next to Bob, I started a horrible sketch of wrestling apatosaurs. Sure enough, Bob, saw what I was doing, internally decided it ought to be done properly, and produced this:
What I love most about this (beside the casual way he knocked it out in fifteen minutes) is the sense of heft about the apatosaurs. These are big, solid animals. Someone’s gonna get hurt.
September 20, 2015
Last time, we looked at some of Brian Engh’s preliminary sketches of pieces to illustrate our fighting-apatosaur hypothesis. But there’s more: some way into the process, Brian also came up with this very rough sketch, illustrating a different style of combat:
All the pictures in the previous post show various forms of ventral-to-ventral combat, but we’ve also been thinking about possibilities, and an important one is ventral-to-dorsal.
That could work in at least two ways. We can imagine a wresting match, where each animal tries to get its neck above its opponent’s, and to force it to the ground. There is precedent for this in the behaviour of various extant animals. (Or perhaps I should call it postcedent, since apatosaurs came first.)
But other extant animals have a much more violent combat style, based on striking blows rather than exerting steady force. Notably, giraffes do this, using their long necks as levers to crash their uncharismatic, highly fused mammalians heads into each other.
Could apatosaurs have done this? Not exactly: their heads were far too small to be effective clubs, and far too fragile to survive being used in this way. But the necks themselves would have been formidable weapons: we’re confident that apatosaurs striking blows would have done so with their necks, bringing them powerfully downwards on their adversaries.
Brian liked this idea enough to work the rough sketch above up into a completed drawing, which we also plan to include in the paper (and which, by the way, I unreservedly love):
So what style of combat did apatosaurs use? Ventral-on-ventral shoving? Wrestling to the ground? Striking downwards blows with the neck?
My best guess (and it’s only a guess, necessarily) is that among the half-dozen or so recognised species of apatosaurine, all these styles were likely in use. And this may explain the variation in cervical morphology that we see between species (though of course ontogeny and sexual dimorphism may also be at work).
In short, I think all of these scenarios are credible — and therefore perfectly legitimate subjects for palaeo-art *hint hint*.
September 19, 2015
In putting together our thoughts on how apatosaurs used their necks, we were motivated by genuine curiosity — which in Matt’s and my case, at least, goes back many years. (We briefly discussed the problem, if only to throw our hands up in despair, in our 2013 neck-anatomy paper.) We didn’t land on the combat hypothesis because it’s cool, but because it’s where the evidence points.
That said, it is cool.
Brian Engh is on the authorship for this paper largely because of his insights into extant animal behaviour. But there’s no denying that it’s a real bonus that he’s also an awesome artist. He’s been putting together sketches to illustrate our hypothesis for some time, partly with the goal of figuring out which compositions to work up into finished pieces. Here, with Brian’s permission, are some of those preliminary sketches.
First, a really nice sketch showing a ventral-to-ventral shoving match from down at ground level.
I really like this one, and would have been happy for it to be one of the anointed ones. I like the sense of huge beasts towering over the viewer. That said, I always love pencil sketches, often more than I do finished pieces, so I’m not too unhappy that the world gets to see this one in pencil-sketch form.
Next up, sketched more roughly, is a concept for a different form of combat in a different aspect. Here, we see two animals side by side, wrestling with both necks and tails.
I like the dynamism of this one, and especially that the one on the right is in the process of being pushed over. But there’s nothing in apatosaur tail morphology that particularly says “combat”, so I guess I’m not too unhappy that this one didn’t make the cut.
The third sketch shows two individuals rearing into into ventral-to-ventral push.
Matt and Brian liked this one the most, so it got worked up into a finished and coloured piece which will be one of the figures in the paper when we get around to submitting it. Here is the current version — as I understand it, Brian plans to revise it further before it’s done.
The craftsmanship here is superb, but I can’t help regretting that the dinosaurs are rearing less than in the sketch. I feel it’s lost some of the power of the concept sketch.
What you’re seeing here, folks, is a bona fide instance of co-authors disagreeing. Happens all the time, but you usually don’t see it, because it’s all resolved by the time the paper is submitted. Brian is the artist, and ultimately it’s for him to decide what to depict and how; but I’ll always be glad that we still have the pencil-sketch as well as the finished version.
September 14, 2015
We’ve noted that the Taylor et al. SVPCA abstract and talk slides are up now up as part of the SVPCA 2015 PeerJ Collection, so anyone who’s interested has probably taken a look already to see what it was about. (As an aside, I am delighted to see that two more abstracts have been added to the collection since I wrote about it.)
It was my privilege to present a talk on our hypothesis that the distinctive and bizarre toblerone-shaped necks of apatosaurs were an adaptation for intraspecific combat. This talk was based on an in-progress manuscript that Matt is lead-authoring. Also on board is the third SV-POW!sketeer, the silent partner, Darren Naish; and artist/ethologist Brian Engh.
Here is our case, briefly summarised from five key slides. First, let’s take a look at what is distinctive in the morphology of apatosaur cervicals:
Here I’m using Brontosaurus, which is among the more extreme apatosaurs, but the same features are seen developed to nearly the same extent in Apatosaurus louisae, the best-known apatosaur, and to some extent in all apatosaurs.
Now we’ll look at the four key features separately.
First, the cervicals ribs of sauropods (and other saurischians, including birds) anchored the longus colli ventralis and flexor colli lateralis muscles — ventral muscles whose job is to pull the neck downwards. By shifting the attachments points of these muscles downwards, apatosaurs enabled them to work with improved mechanical advantage — that is, to bring more force to bear.
Second, by redirecting the diapophyses and parapophyses ventrally, and making them much more robust than in other sauropods, apatosaurs structured their neck skeletons to better resist ventral impacts.
Third, because the low-hanging cervical ribs created an inverted “V” shape below the centrum, they formed a protective cradle for the vulnerable soft-tissue that is otherwise exposed on the ventral aspect of the neck: trachea, oesophagus, major blood vessels. In apatosaurus, all of these would have been safely wrapped in layers of connective tissue and bubble-wrap-like pneumatic diverticula. The presence of diverticula ventral to the vertebral centrum is not speculative – most neosauropods have fossae on the ventral surfaces of their cervical centra, and apatosaurines tend to have foramina that connect to internal chambers as well (see Lovelace et al. 2007: fig. 4, which is reproduced in this post).
Fourth, most if not all apatosaurs have distinctive ventrally directed club-like processes on the front of their cervical ribs. (It’s hard to tell with Apatosaurus ajax, because the best cervical vertebra of that species is so very reconstructed.) How did these appear in life? It’s difficult to be sure. They might have appeared as a low boss; or, as with rhinoceros horns, they might even have carried keratinous spikes.
Putting it all together, we have an animal whose neck can be brought downwards with great force; whose neck was mechanically capable of resisting impacts on its ventral aspect; whose vulnerable ventral-side soft-tissue was well protected; and which probably had prominent clubs or spikes all along the ventral aspect of the neck. And all of this was accomplished at the cost of making the neck a lot heavier than it would have been otherwise. Off the cuff, it seems likely that the cervical series alone would have massed twice as much in apatosaurines as in diplodocines of the same neck length.
Doubling the mass of the neck is a very peculiar thing for a sauropod lineage to do – by the Late Jurassic, sauropods were the leading edge of an evolutionary trend to lengthen and lighten the neck that had been running for almost 100 million years, through basal ornithodirans, basal dinosauromorphs, basal saurischians, basal sauropodomorphs, and basal sauropods. Whatever the selective pressures that led apatosaurines to evolve such robust and heavy necks, they must have been compelling.
The possibility that apatosaurs were pushing or crashing their necks ventrally in some form of combat accounts for all of the weird morphology documented above, and we know that sexual selection is powerful force that underlies a lot of bizarre structures in extant animals, and probably in extinct ornithodirans as well (see Hone et al. 2012, Hone and Naish 2013).
What form of combat, exactly? There are various possibilities, which we’ll discuss another time. But I’ll leave you with Brian Engh’s beautiful illustration of one possible form of combat: a powerful impact of one neck brought down onto the dorsal aspect of another.
We’re aware that this proposal is necessarily somewhat speculative. But we’re just not able to see any other explanation for the distinctive apatosaur neck. Even if we’re wrong about the ventrolateral processes on the cervical ribs supporting bosses or spikes, the first three points remain true, and given how they fly in the face of sauropods’ long history of making their necks lighter, they fairly cry out for explanation. If anyone has other proposals, we’ll be happy to hear them.
- Hone, D. W., Naish, D., & Cuthill, I. C. (2012). Does mutual sexual selection explain the evolution of head crests in pterosaurs and dinosaurs?. Lethaia 45(2):139-156.
- Hone, D. W. E., & Naish, D. (2013). The ‘species recognition hypothesis’ does not explain the presence and evolution of exaggerated structures in non‐avialan dinosaurs. Journal of Zoology 290(3):172-180.
- Lovelace, D. M., Hartman, S. A., & Wahl, W. R. (2007). Morphology of a specimen of Supersaurus (Dinosauria, Sauropoda) from the Morrison Formation of Wyoming, and a re-evaluation of diplodocid phylogeny. Arquivos do Museu Nacional, Rio de Janeiro 65(4):527-544.
September 9, 2015
As we’ve previously noted more than once here at SV-POW!, apatosaurine cervicals really are the craziest things. For one thing, they are the only dinosaur bones to have inspired the design of a Star Wars spaceship.
One result of this very distinctive cervical shape, with the ribs hanging down far below the centra, was that the necks of apatosaurines would have been triangular in cross-section, rather than tubular as often depicted. (The Apatosaurus maquette that Matt reviewed gets this right.)
Here’s how I conveyed this in two slides of my SVPCA talk:
Although apatosaurs take this to the extreme, the same was essentially true of all sauropod necks. The ventrolateral position of the cervical ribs would have lent the necks a rounded triangular shape, or diamond-shaped in the case of less extreme sauropods whose neck soft-tissue hung below the cervical ribs.
The first hypothesis is that, contra Elk (1972), all Brontosauruses were rather fat at one end, then much fatter in the middle, then thin at the other end.
The second theory is that Diplodocus was dumb. Evidence is here presented in the form of an important new life restoration by Matthew Taylor.
- Elk, Anne. 1972. Anne Elk’s Theory on Brontosauruses. Reprinted in: Chapman, G., Cleese, J., Gilliam, T., Idle, E., Jones, T. and Palin, M. (eds). Just the Words, Volume 2. Methuen, London, 118-120.
In a recent post I showed some photos of the mounted apatosaurine at the American Museum of Natural History in New York, AMNH 460, which Tschopp et al. (2015) regarded as an indeterminate apatosaurine pending further study.
A lot of museums whose collections and exhibits go back to the late 19th and early 20th centuries have scale model skeletons and sculptures that were used to guide exhibit design. I have always been fascinated by these models, partly because they’re windows into another era of scientific research and science communication, and partly because they’re just cool – basically the world’s best dinosaur toys – and I covet them. In my experience, it is very, very common to find these treasures of history buried in collections, stuck up on top of specimen cabinets, or otherwise relegated to some out-of-the-way corner where they won’t be in the way. I know that exhibit space is always limited, and these old models often reflect ideas about anatomy, posture, or behavior that we now know to be mistaken. But I am always secretly thrilled when I see these old models still on exhibit.
The AMNH has a bunch of these things, because Henry Fairfield Osborn was crazy about ’em. He not only used 2D skeletal reconstructions and 3D model skeletons to guide exhibit design, he published on them – see for example his 1898 paper on models of extinct vertebrates, his 1913 paper on skeleton reconstructions of Tyrannosaurus, and his 1919 paper with Charles Mook on reconstructing Camarasaurus. That genre of scientific paper seems to have disappeared. I wonder if the time is right for a resurgence.
So in a glass case at the feet of AMNH 460 is a model – I’d guess about 1/12 or 1/15 scale – of that very skeleton. You can tell that it’s a model of that particular skeleton and not just some average apatosaur by looking carefully at the vertebrae. Apatosaurines weren’t all stamped from quite the same mold and the individual peculiarities of AMNH 460 are captured in the model. It’s an amazing piece of work.
The only bad thing about it is that – like almost everything behind glass at the AMNH – it’s very difficult to photograph without getting a recursive hell of reflections. But at least it’s out where people can see and marvel at it.
Oh, and those are the cervical vertebrae of Barosaurus behind it – Mike and I spent more time trying to look and shoot past this model than we did looking at it. But that’s not the model’s fault, those Barosaurus cervicals are just ridiculously inaccessible.
So, memo to museums: at least some of us out here are nuts about your old dinosaur models, and where there’s room to put them on exhibit, they make us happy. They also give us views of the skeletons that we can’t get otherwise, so they serve a useful education and scientific purpose. More, please.
Osborn, H. F. (1898). Models of extinct vertebrates. Science, New Series, 7(192): 841-845.
Osborn, H.F. (1913). Tyrannosaurus, restoration and model of the skeleton. Bulletin of the American Museum of Natural History, 32: 91-92, plates 4-6.
Osborn, H. F., & Mook, C. C. (1919). Characters and restoration of the sauropod genus Camarasaurus Cope. From type material in the Cope Collection in the American Museum of Natural History. Proceedings of the American Philosophical Society, 58(6): 386-396.