The more I look at the problem of how flexible sauropod necks were, the more I think we’re going to struggle to ever know their range of motion It’s just too dependent on soft tissue that doesn’t fossilise. Consider for example the difference between horse necks (above) and camel necks (below).

The skeletons of both consist of vertebrae that are pronouncedly opisthocoelous (convex in front and concave behind), so you might think their necks would be similarly flexible.

But the balls of horse cevicals are deeply embedded in their corresponding sockets, while those of camels have so much cartilage around and between them that the tip of the ball doesn’t even reach the rim of the socket. As a result of this (and maybe other factors), camel necks are far more flexible than those of horses.

Which do sauropod necks resemble? We don’t currently know, and we may never know. It will help if someone gets a good handle on osteological correlates of intervertebral cartilage.

 


[This post is recycled and expanded from a comment that I left on a Tetrapod Zoology post, but since Tet Zoo ate that comment it’s just as well I kept a copy.]

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A while back — near the start of the year, in fact — Szymon Górnicki interviewed me by email about palaeontology, alternative career paths, open access, palaeoart, PeerJ, scholarly infrastructure, the wonder of blogging, and how to get started learning about palaeo. He also illustrated it with this caricature of me, nicely illustrating our 2009 paper on neck posture.

For one reason and another, it’s taken a long while for me get around to linking to it — but here we are in October and I’ve finally arrived :-)

With apologies to Szymon for the delay: here is the interview!

By the way, Szymon’s also done interviews with other, more interesting people: Davide Bonadonna, Steve Brusatte, Tim Haines and Phil Currie. Check them out!

Thanks to everyone who’s engaged with yesterday’s apparently trivial question: what does it mean for a vertebra to be “horizontal”? I know Matt has plenty of thoughts to share on this, but before he does I want to clear up a couple of things.

This is not about life posture

First, and I really should have led with this: the present question has nothing to do with life posture. For example, Anna Krahl wrote on Twitter:

I personally find it more comprehensible if the measurements relate to something like eg. the body posture. This is due to my momentary biomech./functional work, where bone orientation somet is difficult to define.

I’m sympathetic to that, but we really need to avoid conflating two quite different issues here.

Taylor, Wedel and Naish (2009), Figure 1. Cape hare Lepus capensis RAM R2 in right lateral view, illustrating maximally extended pose and ONP: skull, cervical vertebrae 1-7 and dorsal vertebrae 1-2. Note the very weak dorsal deflection of the base of the neck in ONP, contrasting with the much stronger deflection illustrated in a live rabbit by Vidal et al. (1986: fig. 4). Scalebar 5 cm.

If there’s one thing we’ve learned in the last couple of decades, it’s that life posture for extinct animals is controversial — and that goes double for sauropod necks. Heck, even the neck posture of extant animals is terribly easy to misunderstand. We really can’t go changing what we mean by “horizontal” for a vertebra based on the currently prevalent hypothesis of habitual posture.

Also, note that the neck posture on the left of the image above is close to (but actually less extreme than) the habitual posture of rabbits and hares: and we certainly wouldn’t want to illustrate vertebrae as “horizontal” when they’re oriented directly upwards, or even slightly backwards!

Instead, we need to imagine the animal’s skeleton laid out with the whole vertebral column in a straight line — sort of like Ryder’s 1877 Camarasaurus, but with the tail also elevated to the same straight line.

Ryder’s 1877 reconstruction of Camarasaurus, the first ever made of any sauropod, modified from Osborn & Mook (1921, plate LXXXII).

Of course, life posture is more important, and more interesting, question than that of what constitutes “horizontal” for an individual vertebra — but it’s not the one we’re discussing right now.

In method C, both instances are identically oriented

I’m not sure how obvious this was, but I didn’t state it explicitly. In definition C (“same points at same height in consecutive vertebrae”), I wrote:

We use two identical instances of the vertebrae, articulate them together as well as we can, then so orient them that the two vertebrae are level

What I didn’t say is that the two identical instances of the vertebrae have to be identically oriented. Here’s why this is important. Consider that giraffe C7 that we looked at last time, with its keystoned centrum. if you just “articulate them together as well as we can” without that restriction, you end up with something like this:

Which is clearly no good: there’s no way to orient that such that for any given point on one instance, the corresponding point on the other is level with it. What you need instead is something like this:

In this version, I’ve done the best job I can of articulating the two instances in the same attitude, and arranged them such that they are level with each other — so that the attitude shown here is “horizontal” in sense C.

As it happens, this is also just about horizontal in sense B — the floor of the neural canal is presumably at the same height as the top of the centrum as it meets the neural arch.

But “horizontal” in sense A (posterior articular surface vertical) fails horribly for this vertebra:

To me, this image alone is solid evidence that Method A is just not good enough. Whatever we mean by “horizontal”, it’s not what this image shows.

References

Here at SV-POW! we’re big fans of the way that animals’ neck skeletons are much more extended, and often much longer, than you would guess by looking at the complete animal, with its misleading envelope of flesh.

Here’s another fine example, from John Hutchinson’s new post A Museum Evolves:

Solitaire (flightless bird), skeleton and taxidermy at University Museum of Zoology at Cambridge (UMZC). Photo by John Hutchinson.

Looking at the stuffed bird, it seems that it could get by perfectly well with half as many cervical vertebra, if only it didn’t carry them in such a strange posture.

Well — I say strange. It seems inefficient, yet it must be doing something useful, because it’s essentially ubiquitous among birds and many mammals … including rabbits, as long-time readers will remember.

This was an interesting exercise. It was my first time generating a poster to be delivered at a conference since 2006. Scientific communication has evolved a lot in the intervening decade, which spans a full half of my research career to date. So I had a chance to take the principles that I say that I admire and try to put them into practice.

It helped that I wasn’t working alone. Jann and Brian both provided strong, simple images to help tell the story, and Mike and I were batting ideas back and forth, deciding on what we could safely leave out of our posters. Abstracts were the first to go, literature cited and acknowledgments were next. We both had the ambition of cutting the text down to just figure captions. Mike nailed that goal, but my poster ended up being slightly more narrative. I’m cool with that – it’s hardly text-heavy, especially compared with most of my efforts from back when. Check out the text-zilla I presented at SVP back in 2006, which is available on FigShare here. I am happier to see, looking back, that I’d done an almost purely image-and-caption poster, with no abstract and no lit cited, as early as 1999, with Kent Sanders as coauthor and primary art-generator – that one is also on FigShare.

I took 8.5×11 color printouts of both my poster and Mike’s, and we ended up passing out most of them to people as we had conversations about our work. That turned out to be extremely useful – I had a 30-minute conversation about my poster at a coffee break the day before the posters even went up, precisely because I had a copy of it to hand to someone else. Like Mike, I found that presenting a poster resulted in more and better conversations than giving a talk. And it was the most personally relaxing SVPCA I’ve ever been to, because I wasn’t staying up late every night finishing or practicing my talk.

I have a lot of stuff to say about the conference, the field trip, the citability of abstracts and posters (TL;DR: I’m for it), and so on, but unfortunately no time right now. I’m just popping in to get this posted while it’s still fresh. Like Mike’s poster, this one is now published alongside my team’s abstract on PeerJ PrePrints.

I will hopefully have much more to say about the content in the future. This is a project that Jann, Brian, and I first dreamed up over a decade ago, when we were grad students at Berkeley. Mike provided the impetus for us to get it moving again, and kindly stepped aside when I basically hijacked his related but somewhat different take on ontogeny and serial homology. When my fall teaching is over, I’m hoping that the four of us can take all of this, along with additional examples found by Mike that didn’t make it into this presentation, and shape it into a manuscript. I’ll keep you posted on that. In the meantime, the comment field is open. For some related, previously-published posts, see this one for the baby sauropod verts, this one for CM 555, and this one for Plateosaurus.

Flying over Baffin Island on the way home.

And finally, since I didn’t put them into the poster itself, below are the full bibliographic references. Although we didn’t mention it in the poster, the shell apex theory for inferring the larval habits of snails was first articulated by G. Thorson in 1950, which is referenced in full here.

Literature Cited

mark-and-matt-with-the-sauropod-dinosaurs

Quick heads up: Mark Hallett and I are both at the Society of Vertebrate Paleontology meeting in Salt Lake City. Tomorrow afternoon (Friday, October 28) at 4:15 PM we’ll be signing copies of our book, The Sauropod Dinosaurs: Life in the Age of Giants. If you’d like to get a copy of the book, or to have your already-purchased copy signed, please come to the Johns Hopkins University Press booth in the exhibitor/poster area tomorrow afternoon. We’re both generally happy to sign books whenever and wherever, but if you’d like to catch us both at the same time, this is a good opportunity. We’re hoping to do another joint book signing in Los Angeles before long – more info on that when we get it arranged.

In the meantime, or if you’re not at SVP, or if you just like cool things, check out this rad claymation video of fighting apatosaurs, by YouTube user Fred the Dinosaurman. I love this. My favorite thing is that if you’re familiar with the previously-produced, static visual images of neck-fighting apatosaurs (links collected here), you’ll see a lot of those specific poses and moments recreated as transient poses in the video. This was published back in June, but I’d missed it – many thanks to Brian Engh for the heads up.

Long-time SV-POW! readers will remember that three years ago, full of enthusiasm after speaking about Barosaurus at the Edinburgh SVPCA, Matt and I got that talk written up in double-quick time and had it published as a PeerJ Preprint in less than three weeks. Very quickly, the preprint attracted substantive, helpful reviews: three within the first 24 hours, and several more in the next few days.

This was great: it gave us the opportunity to handle those review comments and get the manuscript turned around into an already-reviewed formal journal submission in less then a month from the original talk.

So of course what we did instead was: nothing. For three years.

I can’t excuse that. I can’t even explain it. It’s not as though we’ve spent those three years churning out a torrent of other awesome papers. We’ve both just been … a bit lame.

Anyway, here’s a story that will be hauntingly familiar. A month ago, full of enthusiasm after speaking about Barosaurus at the Liverpool SVPCA, Matt and I found ourselves keen to write up that talk in double-quick time. It’s an exciting tale of new specimens, reinterpretation of an important old specimen, and a neck eight times as long as that 0f a world-record giraffe.

But it would be crazy to write the new Barosaurus paper without first having dealt with the old Barosaurus paper. So now, finally, three years on, we’ve done that. Version 2 of the preprint is now available (Taylor and Wedel 2016), incorporating all the fine suggestions of the people who reviewed the first version — and with a slightly spiffed-up title. What’s more, the new version has also been submitted for formal peer-review. (In retrospect, I can’t think why we didn’t do that when we put the first preprint up.)

Taylor and Wedel 2016: Figure 3. Barosaurus lentus holotype YPM 429, vertebra R, C?15. Top row: dorsal view; middle row, left to right: posterior, right lateral and anterior views; bottom row: ventral view, from Lull (1919: plate II). Note the apparently very low, undivided neural spine at the intersection of the PRSLs and POSLs, forward-shifted neural arch, broad prezygapophyses, broad, wing-like prezygadiapophyseal laminae, and great width across the diapophyses and across the parapophyses. Abbreviations: dia, diapophysis; para, parapophysis; prz, prezygapophysis; prdl, prezygadiapophyseal lamina; spol, spinopostzygapophyseal lamina; sprl, spinoprezygapophyseal lamina. Scale bar = 500 mm.

Taylor and Wedel 2016: Figure 3. Barosaurus lentus holotype YPM 429, vertebra R, C?15. Top row: dorsal view; middle row: posterior, right lateral and anterior views; bottom row: ventral view, from Lull (1919: plate II). Note the apparently very low, undivided neural spine at the intersection of the SPRLs and SPOLs, forward-shifted neural arch, broad prezygapophyses, broad, wing-like prezygadiapophyseal laminae, and great width across the diapophyses and across the parapophyses. Abbreviations: dia, diapophysis; para, parapophysis; prz, prezygapophysis; prdl, prezygadiapophyseal lamina; spol, spinopostzygapophyseal lamina; sprl, spinoprezygapophyseal lamina. Scale bar = 500 mm.

A big part of the purpose of this post is to thank Emanuel Tschopp, Mark Robinson, Andy Farke, John Foster and Mickey Mortimer for their reviews back in 2013. I know it’s overdue, but they are at least all acknowledged in the new version of the manuscript.

Now we cross our fingers, and hope that the formally solicited reviews for the new version of the manuscript are as helpful and constructive as the reviews in that first round. Once those reviews are in, we should be able to move quickly and painlessly to a formally published version of this paper. (I know, I know — I shouldn’t offer such a hostage to fortune.)

Meanwhile, I will finally be working on handling the reviews of this other PeerJ submission, which I received back in October last year. Yes, I have been lax; but I am back in the saddle now.

References

  • Taylor, Michael P., and Mathew J. Wedel. 2016. The neck of Barosaurus: longer, wider and weirder than those of Diplodocus and other diplodocines. PeerJ PrePrints 1:e67v2 doi:10.7287/peerj.preprints.67v2