October 9, 2015
Since I posted my preprint “Almost all known sauropod necks are incomplete and distorted” and asked in the comments for people to let me know if I missed any good necks, the candidates have been absolutely rolling in:
- The Kaatedocus siberi holotype SMA 0004 (thanks to Oliver Demuth for pointing this out)
- The Futalognkosaurus dukei holotype MUCPv-323 (thanks to Matt Lamanna)
- The referred Rapetosaurus specimen FMNH PR 2209 (Matt Lamanna again)
- The as-yet unnnamed DGM ‘Series A’ titanosaur from Peirópolis (Matt Lamanna again)
- The Camarasaurus lewisi holotype BYU 9047 (thanks to John D’Angelo)
- Dicraeosaurus hansemanni — the mounted “m” specimen, probably MB.R.4886 (thanks to Emanuel Tschopp)
- Maybe some Omeisaurus specimens (Emanuel Tschopp again)
I will be investigating the completeness of all of these and mentioning them as appropriate when I submit the revision of this paper. (In retrospect, I should have waited a week after posting the preprint before submitting for formal review; but I was so scared of letting it brew for years, as we’re still doing with the Barosaurus preprint to our shame, that I submitted it immediately.)
So we probably have a larger number of complete or near-complete sauropod necks than the current draft of this paper suggests. But still very few in the scheme of things, and essentially none that aren’t distorted.
So I want to consider why we have such a poor fossil record of sauropod necks. All of the problems with sauropod neck preservation arise from the nature of the animals.
First, sauropods are big. This is a recipe for incompleteness of preservation. (It’s no accident that the most completely preserved specimens are of small individuals such as CM 11338, the cow-sized juvenile Camarasaurus lentus described by Gilmore, 1925). For an organism to be fossilised, the carcass has to be swiftly buried in mud, ash or some other substrate. This can happen relatively easily to small animals, such as the many finely preserved stinkin’ theropods from the Yixian Formation in China, but it’s virtually impossible with a large animal. Except in truly exceptional circumstances, sediments simply don’t get deposited quickly enough to cover a 25 meter, 20 tonne animal before it is broken apart by scavenging, decay and water transport.
Secondly, even when complete sauropods are preserved, or at least complete necks, distortion of the preserved cervical vertebrae is almost inevitable because of their uniquely fragile construction. As in modern birds, the cervical vertebrae were lightened by extensive pneumatisation, so that they were more air than bone, with the air-space proportion typically in the region of 60–70% and sometimes reaching as high as 89%. While this construction enabled the vertebrae to withstand great stresses for a given mass of bone, it nevertheless left them prone to crushing, shearing and torsion when removed from their protective layer of soft tissue. For large cervicals in particular, the chance of the shape surviving through taphonomy, fossilisation and subsequent deformation would be tiny.
So I think we’re basically doomed never to have a really good sauropod neck skeleton.
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“.
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.
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.
September 30, 2015
Here’s the last post (at least for now) in the Fighting Apatosaur Art series — and we’re back to Brian Engh, who we started with.
Early in the process of putting together artwork to illustrate our apatosaur neck combat hypothesis, Brian tried out a whole bunch of outlandish concepts. Here are two that he showed us, but which were too speculative to push forward with. First, necks as big, floppy display structures:
As a piece of art, I really like this one: the boldness, the vivid contrasts, the alien quality of the animals. But as a palaeobiological hypothesis, it doesn’t really work: so much of the neck morphology in apatosaurs is to do with absorbing ventral forces that soft-tissue display structures down there don’t make a whole lot of sense.
Here’s the other one — which Brian titles “Apatosaur inflato-porcupine fish neck-bag”.
I particularly like the way the theropod being rolled around on the ground and repeatedly spiked. It’s no more than it deserves.
Does the idea of an inflatable neck make sense? I wouldn’t be at all surprised if there were sauropods that did something like this — plenty of extant animals inflate parts of their body for display purposes, after all — but I don’t think it would have been apatosaurs. Again, the characteristic features of the neck don’t seem well matched to this scenario.
Well, that’s all the apatosaur neck-combat art we have. If there’s to be a part 7 in this series, it will be made of artwork that you, dear readers, have contributed. Fire away!
September 28, 2015
If we accept that the distinctive ventral projections of the gigantic and ventrally displaced cervical ribs of apatosaurs were likely the base of some form of soft-tissue rugosity — such as keratinous horns like those of rhinos — then does it follow that those necks were used in combat as we suggested?
Maybe, maybe not. As scientists, we are always open to other hypotheses. We’re looking for the simplest, most parsimonious model — the one which best explains the facts.
That’s why we like Mark Witton’s “neck-velcro wall-climbing” hypothesis, as shown in this actual scientific life restoration.
As Mark explained to me, apatosaurs may have used their neck-hooks for more than passive clinging. They may also have been used for inching up the rock-face: first one side of the neck advancing and then the next, in the manner of the “pterygoid walking” that snakes use to progressively swallow large prey.
This is why it’s important to present early-stage work at conferences (and as preprints). Otherwise, you may never hear about important alternative hypotheses like this until after the paper is out and it’s too late to include them.
September 27, 2015
I mentioned last time that, as I sat next to Bob Nicholls in an SVPCA session, I started sketching an apatosaur combat in the hope that my horrible drawing would provoke Bob to do a good one. That worked admirably, which means there is no good reason for me to subject you to my own sketch.
So here it is.
I think the main lessons to draw from this piece are:
- I can’t draw heads.
- I can’t draw limbs.
- I can’t draw torsos.
- I may be just about capable of drawing tails.
During a break, I asked for Bob’s advice on how I can do better. I know I’ll never be an artist, but it’s fun to sketch (especially during mammal talks) and I’d like to improve a little. The main point Bob made was to think about where the light is coming from. Be consistent about that, and you get an immediate improvement in realism.
So here’s what I sketched the next day, with that in mind:
So what have we learned this time?
- I didn’t consciously do this, but I ended up with a composition kind of similar to what Bob came up with, but worse.
- In my desire to achieve the intertwined-necks pose, I made the necks too long and thin.
- I still can’t draw heads.
- Let’s just forget about the hindlimb of the one on the left.
- Uh, and let’s forget the torsos, too.
- But at least the light is coming from top right!
In short, as Stephen Sondheim put it, art isn’t easy. I wish I had more time to put into it.
The real moral of this story is: if I had a crack at drawing fighting apatosaurs, you definitely can. Let us know if you do — leave a comment. We’ll gather people’s contributions in a future post.
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*.