October 21, 2014
In light of yesterday’s tutorial on choosing titles, here are the titles of all my own published papers (including co-authored ones), in chronological order, with my own sense of whether I’m happy with them now I look back. All the full references are on my publications page (along with the PDFs). I’ll mark the good ones in green, the bad ones in red and the merely OK in blue.
The Phylogenetic Taxonomy of Diplodocoidea (Dinosauria: Sauropoda).
OK, I suppose. It does at least clearly state what the paper is about. I’ll give myself a pass on this since it was my very first paper.
Dinosaur diversity analysed by clade, age, place and year of description.
NOT BAD, since the paper was basically a list of many, many results that could hardly have been summarised in the title. I give myself some points for listing the ways I analysed the data, rather than just saying “An analysis of dinosaur diversity” or something equally uninformative.
Phylogenetic definitions in the pre-PhyloCode era; implications for naming clades under the PhyloCode.
NOT BAD again, I suppose, since it was a discussion paper that couldn’t be summarised in a short title. Could I have said what the alluded-to implications are? I think probably not, in a reasonably concise title.
An unusual new neosauropod dinosaur from the Lower Cretaceous Hastings Beds Group of East Sussex, England.
RUBBISH, since it doesn’t name the new dinosaur (which was of course Xenoposeidon). I was young and stupid back then, and just followed convention. In mitigation, it does at least say when and where the specimen is from.
Case 3472: Cetiosaurus Owen, 1841 (Dinosauria, Sauropoda): proposed conservation of usage by designation of Cetiosaurus oxoniensis Phillips, 1871 as the type species.
DOUBLE-PLUS UGLY. But I am going to blame the journal on this one — they have a very firmly defined format for petition titles.
Head and neck posture in sauropod dinosaurs inferred from extant animals.
RUBBISH. What was I thinking, and why did my SV-POW!sketeer co-authors let me choose such an uninformative title? We should of course have gone with a title that says what posture we inferred. The associated blog-post had a much better title: Sauropods held their necks erect … just like rabbits.
A re-evaluation of Brachiosaurus altithorax Riggs 1903 (Dinosauria, Sauropoda) and its generic separation from Giraffatitan brancai (Janensch 1914).
ADEQUATE, since the title strongly implies the conclusion (generic separation) even if doesn’t quite come out and say it.
Electronic publication of nomenclatural acts is inevitable, and will be accepted by the taxonomic community with or without the endorsement of the Code.
BRILLIANT. The best title in my CV. You hardly even need to read the paper once you’ve read the title. The only downside: it’s 12 characters too long to tweet.
Sharing: public databases combat mistrust and secrecy.
GOOD, but I can’t take the credit for that (A) because I was third author behind Andy Farke and Matt, and (B) because the journal chose the title.
The Open Dinosaur Project.
OK, but we should have done better. Something like “The Open Dinosaur Project recruits volunteer effort to analyse dinosaur evolution”. Or, if we were being honest (and prescient), “The Open Dinosaur Project will lie embarrassingly moribund for more than two years”.
Sauropod dinosaur research: a historical review.
OK, since it does say what the paper is. But this title is not as good as that of the talk it was based on, “The evolution of sauropod dinosaurs from 1841 to 2008″. (I notice that Mark Witton nicked my title for his talk at TetZooCon.)
Running a question-and-answer website for science education: first hand experiences.
UNOBJECTIONABLE, but not my choice anyway — lead author Dave Hone presumably picked it. Could have done better by stating what at least one of those experiences was.
A new sauropod dinosaur from the Lower Cretaceous Cedar Mountain Formation, Utah, USA.
RUBBISH. At least this time it wasn’t entirely my fault. When we submitted this to Acta Palaeontologica Polonica, it was called “Brontomerus mcintoshi, a new sauropod dinosaur from the Lower Cretaceous Cedar Mountain Formation, Utah, USA”, but the journal made us take the taxon name out of the title. Why? Why why WHY?
The long necks of sauropods did not evolve primarily through sexual selection.
Why sauropods had long necks; and why giraffes have short necks.
EXCELLENT. Short, appealing and (hopefully) funny. When I give talks based on this paper, I use the even better short version, just “Why giraffes have short necks”. But that seemed a bit too cute for an academic setting.
Neural spine bifurcation in sauropod dinosaurs of the Morrison Formation: ontogenetic and phylogenetic implications.
WEAK. We should have stated the conclusion: a title like “Neural spine bifurcation in sauropods of the Morrison Formation is not an ontogenetic feature, but is phylogenetically significant” would have been better.
The neck of Barosaurus was not only longer but also wider than those of Diplodocus and other diplodocines.
GOOD. Not particularly exciting, but explicit.
Caudal pneumaticity and pneumatic hiatuses in the sauropod dinosaurs Giraffatitan and Apatosaurus.
NOT GOOD ENOUGH. We should have stated the main finding: “Caudal pneumaticity and pneumatic hiatuses reveal cryptic diverticula in the sauropod dinosaurs Giraffatitan and Apatosaurus“.
The effect of intervertebral cartilage on neutral posture and range of motion in the necks of sauropod dinosaurs.
UGH, rubbish. What the heck was I thinking? I should have written this post a couple of years ago, and used it to make me choose a much better title. As it is, it just leaves the reader assuming intervertebral cartilage probably has some effect, but they have no idea what.
I make that six good titles, seven bad ones and six indifferent. Awarding two points per good title and one per adequate title, I give myself 18 points out of a possible 38 — slightly less than half, at 47%. More worryingly, there’s no apparent trend towards choosing better titles.
Must do better.
May 7, 2014
[NOTE: see the updates at the bottom. In summary, there’s nothing to see here and I was mistaken in posting this in the first place.]
Elsevier’s War On Access was stepped up last year when they started contacting individual universities to prevent them from letting the world read their research. Today I got this message from a librarian at my university:
The irony that this was sent from the Library’s “Open Access Team” is not lost on me. Added bonus irony: this takedown notification pertains to an article about how openness combats mistrust and secrecy. Well. You’d almost think NPG wants mistrust and secrecy, wouldn’t you? It’s sometimes been noted that by talking so much about Elsevier on this blog, we can appear to be giving other barrier-based publishers a free ride. If we give that impression, it’s not deliberate. By initiating this takedown, Nature Publishing Group has self-identified itself as yet another so-called academic publisher that is in fact an enemy of science. So what next? Anyone who wants a PDF of this (completely trivial) letter can still get one very easily from my own web-site, so in that sense no damage has been done. But it does leave me wondering what the point of the Institutional Repository is. In practice it seems to be a single point of weakness allowing “publishers” to do the maximum amount of damage with a single attack.
But part of me thinks the thing to do is take the accepted manuscript and format it myself in the exact same way as Nature did, and post that. Just because I can. Because the bottom line is that typesetting is the only actual service they offered Andy, Matt and me in exchange for our right to show our work to the world, and that is a trivial service.
The other outcome is that this hardens my determination never to send anything to Nature again. Now it’s not like my research program is likely to turn up tabloid-friendly results anyway, so this is a bit of a null resolution. But you never know: if I happen to stumble across sauropod feather impressions in an overlooked Wealden fossil, then that discovery is going straight to PeerJ, PLOS, BMC, F1000 Research, Frontiers or another open-access publisher, just like all my other work.
And that’s sheer self-interest at work there, just as much as it’s a statement. I will not let my best work be hidden from the world. Why would anyone?
Let’s finish with another outing for this meme-ready image.
David Mainwaring (on Twitter) and James Bisset (in the comment below) both pointed out that I’ve not seen an actual takedown request from NPG — just the takedown notification from my own library. I assumed that the library were doing this in response to hassle from NPG
, but of course it’s possible that my own library’s Open Access Team is unilaterally trying to prevent access to the work of its university’s researchers.
I’ve emailed Lyn Duffy to ask for clarification. In the mean time, NPG’s Grace Baynes has tweeted:
So it looks like this may be even more bizarre than I’d realised.
Further bulletins as events warrant.
OK, consensus is that I read this completely wrong. Matt’s comment below says it best:
I have always understood institutional repositories to be repositories for author’s accepted manuscripts, not for publisher’s formatted versions of record. By that understanding, if you upload the latter, you’re breaking the rules, and basically pitting the repository against the publisher.
Which is, at least, not a nice thing to do to the respository.
So the conclusion is: I was wrong, and there’s nothing to see here apart from me being embarrassed. That’s why I’ve struck through much of the text above. (We try not to actually delete things from this blog, to avoid giving a false history.)
My apologies to Lyn Duffy, who was just doing her job.
This just in from Lyn Duffy, confirming that, as David and James guessed, NPG did not send a takedown notice:
This PDF was removed as part of the standard validation work of the Open Access team and was not prompted by communication from Nature Publishing. We validate every full-text document that is uploaded to Pure to make sure that the publisher permits posting of that version in an institutional repository. Only after validation are full-text documents made publicly available.
In this case we were following the regulations as stated in the Nature Publishing policy about confidentiality and pre-publicity. The policy says, ‘The published version — copyedited and in Nature journal format — may not be posted on any website or preprint server’ (http://www.nature.com/authors/policies/confidentiality.html). In the information for authors about ‘Other material published in Nature’ it says, ‘All articles for all sections of Nature are considered according to our usual conditions of publication’ (http://www.nature.com/nature/authors/gta/others.html#correspondence). We took this to mean that material such as correspondence have the same posting restrictions as other material published by Nature Publishing.
If we have made the wrong decision in this case and you do have permission from Nature Publishing to make the PDF of your correspondence publicly available via an institutional repository, we can upload the PDF to the record.
Open Access Team
Here’s the text of the original notification email so search-engines can pick it up. (If you read the screen-grab above, you can ignore this.)
University of Bristol — Pure
Lyn Duffy has added a comment
Sharing: public databases combat mistrust and secrecy
Farke, A. A., Taylor, M. P. & Wedel, M. J. 22 Oct 2009 In : Nature. 461, 7267, p. 1053
Research output: Contribution to journal › Article
Lyn Duffy has added a comment 7/05/14 10:23
Dear Michael, Apologies for the delay in checking your record. It appears that the document you have uploaded alongside this record is the publishers own version/PDF and making this version openly accessible in Pure is prohibited by the publisher, as a result the document has been removed from the record. In this particular instance the publisher would allow you to make accessible the postprint version of the paper, i.e., the article in the form accepted for publication in the journal following the process of peer review. Please upload an acceptable version of the paper if you have one. If you have any questions about this please get back to us, or send an email directly to email@example.com Kind regards, Lyn Duffy Library Open Access Team.
February 6, 2014
In a recent comment, Doug wrote:
If I want to be a truly educated observer of Tyrannosaurus rex mounts, what 5 things should I look for in a reconstruction to assess if it is true to our current scientific understanding? I’m not talking tail dragging/upright at this point…we are well past that I hope.
If he had asked about Apatosaurus, I could have written him a novel. But it is a point of pride with me not to contribute to the over-application of human attention to T. rex; not only would it be vulgar, it would also be a waste of resources, considering how many people already have that covered. So, you theropod workers and avocational “rexperts”, we’re finally inviting you to the high table. Please, tell us–and Doug–what separates the good T. rex mounts from the crappy ones. Big piles of SV-POW! bucks will be showered on whoever brings the most enlightenment, especially if you adhere to the requested List of 5 Things format.
The comment lines are open–go!
January 15, 2014
[This is part 4 in an ongoing series on our recent PLOS ONE paper on sauropod neck cartilage. See also part 1, part 2, and part 3.]
Here’s a frequently-reproduced quote from Darwin:
About thirty years ago there was much talk that geologists ought only to observe and not theorise; and I well remember some one saying that at this rate a man might as well go into a gravel-pit and count the pebbles and describe the colours. How odd it is that anyone should not see that all observation must be for or against some view if it is to be of any service!
It’s from a letter to Henry Fawcett, dated September 18, 1861, and you can read the whole thing here.
I’ve known this quote for ages, having been introduced to it at Berkeley–a copy used to be taped to the door of the Padian Lab, and may still be. It’s come back to haunt me recently, though. An even stronger version would run something like, “If you don’t know what you’re looking for, you won’t make the observation in the first place!”
For example: I started CT scanning sauropod vertebrae with Rich Cifelli and Kent Sanders back in January, 1998. Back then, I was interested in pneumaticity, so that’s what I looked for, and that’s what I found–work which culminated in Wedel et al. (2000) and Wedel (2003). It wasn’t until earlier this year that I wondered if it would be possible to determine the spacing of articulated vertebrae from CT scans. So everything I’m going to show you, I technically saw 15 years ago, but only in the sense of “it crossed my visual field.” None of it registered at the time, because I wasn’t looking for it.
A corollary I can’t help noting in passing: one of the under-appreciated benefits of expanding your knowledge base is that it allows you to actually make more observations. Many aspects of nature only appear noteworthy once you have a framework in which to see them.
So anyway, the very first specimen we scanned way back when was the most anterior of the three plaster jackets that contain the four cervical vertebrae that make up OMNH 53062, which was destined to become the holotype of Sauroposeidon. I’ve written about the taphonomy of that specimen here, and you can read more about how it was excavated in Wedel and Cifelli (2005). We scanned that jacket first because, although the partial vertebrae it contains are by far the most incomplete of the four, the jacket is a lot smaller and lighter than the other two (which weigh hundreds of pounds apiece). Right away we saw internal chambers in the vertebrae, and that led to all of the pneumaticity work mentioned above.
Happily for me, that first jacket contains not only the posterior two-thirds of the first vertebra (possibly C5), but also the front end of the second vertebra. Whoever decided to plow through the second vertebra to divide the specimen into manageable chunks in the field made a savvy choice. Way back in 2004 I realized that the cut edge of the second vertebra was not obscured by plaster, and therefore the internal structure could be seen and measured directly, which is a lot cleaner than relying on the artifact-heavy CT scans. (The CT scans are noisy because the hospital machines we had access to start to pant a bit when asked to punch x-rays through specimens this large and dense.) A figure derived from that work made it into a couple of papers and this post, and appears again above.
But that’s pneumaticity, which this post is allegedly not about. The cut through the second vertebra was also smart because it left the intervertebral joint intact.
Here are a photo of the jacket and a lateral scout x-ray. The weird rectangles toward the left and right ends of the x-ray are boards built into the bottom of the jacket to strengthen it.
And here’s a closeup of the C5/C6 joint, with the relevant radiographs and tracing. The exciting thing here is that the condyle is centered almost perfectly in the cotyle, and the zygapophyses are in articulation. Together with the lack of disarticulation in the cervical rib bundle (read more about that here and in Wedel et al. 2000), these things suggest to us that the vertebrae are spaced pretty much as they were in life. If so, then the spacing between the vertebrae now tells us the thickness of the soft tissue that separated the vertebrae in life.
I should point out here that we can’t prove that the spacing between the vertebrae is still the same as it was in life. But if some mysterious force moved them closer together or farther apart, it did so (1) without decentering the condyle of C6 within the cotyle of C5, (2) without moving the one surviving zygapophyseal joint out of contact, and (3) without disarticulating the cervical ribs. The cervical ribs were each over 3 meters long in life and they formed vertically-stacked bundles on either side below the vertebrae; that’s a lot of stuff to move just through any hypothetical contraction or expansion of the intervertebral soft tissues after death. In fact, I would not be surprised if the intervertebral soft tissues did contract or expand after death–but I don’t think they moved the vertebrae, which are comparatively immense. The cartilage probably pulled away from the bone as it rotted, allowing sediment in. Certainly every nook and cranny of the specimen is packed with fine-grained sandstone now.
Anyway, barring actual preserved cartilage, this is a best-case scenario for trying to infer intervertebral spacing in a fossil. If articulation of the centra, zygs, and cervical ribs doesn’t indicate legitimate geometry, nothing ever will. So if we’re going to use the fossils to help settle this at all, we’re never going to have a better place to start.
So, by now, you know I’m a doofus. I have been thinking about this problem literally for years and the data I needed to address it was sitting on my hard drive the entire time. One of the things I pondered during those lost years is what the best shape for a concave-to-convex intervertebral joint might be. Would the best spacing be radially constant (A in the figure above), or antero-posteriorly constant (B), or some other, more complicated arrangement? The answer in this case surprised me–although the condyle is a lot smaller in diameter than the cotyle, the anteroposterior separation between them in almost constant, as you can see in part C of the above figure.
Don’t get too worked up about that, though, because the next joint is very different! Here’s the C6/C7 joint, again in a lateral scout x-ray, with the ends of the bones highlighted. Here the condyle is almost as big in diameter as the cotyle, but it is weirdly flat. This isn’t a result of overzealous prep–most of the condyle is still covered in matrix, and I only found its actual extent by looking at the x-ray. This is flatter than most anterior dorsal vertebrae of Apatosaurus–I’ve never seen a sauropod cervical with such a flat condyle. Has anyone else?
The condyle of C6 is a bit flatter than expected, too–certainly a lot flatter than the cervical condyles in Giraffatitan and the BYU Brachiosaurus vertebrae. As we said in the paper,
It is tempting to speculate that the flattened condyles and nearly constant thickness of the intervertebral cartilage are adaptations to bearing weight, which must have been an important consideration in a cervical series more than 11 meters long, no matter how lightly built.
Anyway, obviously here the anteroposterior distance between condyle and cotyle could not have been uniform because they are such different shapes. Wacky. The zygs are missing, so they’re no help, and clearly the condyle is not centered in the cotyle. Whether this posture was attainable in life is debatable; I’ve seen some pretty weird stuff. In any case, we didn’t use this joint for estimating cartilage thickness because we had no reason to trust the results.
Kent Sanders and I had also scanned several of the smaller sauropod vertebrae from the Carnegie collection (basically, the ones that would fit in the trunk of my car for the drive back to Oklahoma). Crucially, we’d scanned a couple of sets of articulated vertebrae, CM 3390 and CM 11339, both from juvenile individuals of Apatosaurus. In both cases, the condyles and cotyles are concentric (that’s what the ‘orthogonal gaps’ are all about in the above figure) and the zygs are in articulation, just as in Sauroposeidon. These are dorsals, so we don’t have any cervical ribs here to provide a third line of evidence that the articulation is legit, but all of the evidence that we do have is at least consistent with that interpretation.
So, here’s an interesting thing: in CM 3390, above, the first dorsal is cranked up pretty sharply compared to the next one, but the condyle is still centered in the cotyle and the zygs are in articulation. Now, the vertebrae have obviously been sheared by taphonomic deformation, but that seems to have affected both vertebrae to the same extent, and it’s hard to imagine some kind of taphonomic pressure moving one vertebra around relative to the next. So I think it’s at least plausible that this range of motion was achievable in life. Using various views and landmarks, we estimate the degree of extension here somewhere between 31 and 36 degrees. That’s a lot more than the ~6 degrees estimated by Stevens and Parrish (1999, 2005). And, as we mentioned in the paper, it nicely reinforces the point made by Upchurch (2000), that flexibility in the anterior dorsals should be taken into account in estimating neck posture and ROM.
Here’s our last specimen, CM 11339. No big surprises here, although if you ever had a hard time visualizing how hyposphenes and hypantra fit together, you can see them in articulation in parts C and D (near the top of the specimen). Once again, by paging through slices we were able to estimate the separation between the vertebrae. Incidentally, the condyle IS centered in the cotyle here, it just doesn’t look that way because the CT slice is at an angle to the joint–see the lateral scout in part A of the figure to see what I mean.
So, what did we find? In Sauroposeidon the spacing between C5 and C6 is 52mm. That’s pretty darn thick in absolute terms–a shade over two inches–but really thin in relative terms–only a little over 4% of the length of each vertebra. In both of the juvenile Apatosaurus specimens, the spacing between the vertebrae was about 14mm (give or take a few because of the inherent thickness of the slices; see the paper for details on these uncertainties).
Now, here’s an interesting thing: we can try to estimate the intervertebral spacing in an adult Apatosaurus in two ways–by scaling up from the juvenile apatosaurus, or by scaling sideways from Sauroposeidon (since a big Apatosaurus was in the same ballpark, size-wise)–and we get similar answers either way.
Scaling sideways from Sauroposeidon (I’m too lazy to write anymore so I’m just copying and pasting from the paper):
Centrum shape is conventionally quantified by Elongation Index (EI), which is defined as the total centrum length divided by the dorsoventral height of the posterior articular surface. Sauroposeidon has proportionally very long vertebrae: the EI of C6 is 6.1. If instead it were 3, as in the mid-cervicals of Apatosaurus, the centrum length would be 600 mm. That 600 mm minus 67 mm for the cotyle would give a functional length of 533 mm, not 1153, and 52 mm of cartilage would account for 9.8% of the length of that segment.
Scaling up from the juveniles: juvenile sauropods have proportionally short cervicals (Wedel et al. 2000). The scanned vertebrae are anterior dorsals with an EI of about 1.5. Mid-cervical vertebrae of this specimen would have EIs about 2, so the same thickness of cartilage would give 12mm of cartilage and 80mm of bone per segment, or 15% cartilage per segment. Over ontogeny the mid-cervicals telescoped to achieve EIs of 2.3–3.3. Assuming the cartilage did not also telescope in length (i.e., didn’t get any thicker than it got taller or wider), the ratio of cartilage to bone would be 12:120 (120 from 80*1.5), so the cartilage would account for 10% of the length of the segment–almost exactly what we got from the based-on-Sauroposeidon estimate. So either we got lucky here with our tiny sample size and truckloads of assumptions, or–just maybe–we discovered a Thing. At least we can say that the intervertebral spacing in the Apatosaurus and Sauroposeidon vertebrae is about the same, once the effects of scaling and EI are removed.
Finally, we’re aware that our sample size here is tiny and heavily skewed toward juveniles. That’s because we were just collecting targets of opportunity. Finding sauropod vertebrae that will fit through a medical-grade CT scanner is not easy, and it’s just pure dumb luck that Kent Sanders and I had gotten scans of even this many articulated vertebrae way back when, since at the time we were on the hunt for pneumaticity, not intervertebral joints or their soft tissues. As Mike has said before, we don’t think of this paper as the last word on anything. It is, explicitly, exploratory. Hopefully in a few years we’ll be buried in new data on in-vivo intervertebral spacing in both extant and extinct animals. If and when that avalanche comes, we’ll just be happy to have tossed a snowball.
- Stevens, K.A. and Parrish, J.M. 1999. Neck posture and feeding habits of two Jurassic sauropod dinosaurs. Science 284: 798-800. [Free subscription required]
- Stevens, Kent A., and J. Michael Parrish. 2005. Neck posture, dentition, and feeding strategies in Jurassic sauropod dinosaurs. pp. 212-232 in: Virginia Tidwell and Ken Carpenter (eds.), Thunder Lizards: the Sauropodomorph Dinosaurs. Indiana University Press, Bloomington, Indiana. 495 pp.
- Taylor, Michael P., and Mathew J. Wedel. 2013c. The effect of intervertebral cartilage on neutral posture and range of motion in the necks of sauropod dinosaurs. PLOS ONE 8(10): e78214. 17 pages. doi:10.1371/journal.pone.0078214 [PDF]
- Upchurch, P. 2000. Neck posture of sauropod dinosaurs. Science 287: 547b.
- Wedel, M.J. 2003b. The evolution of vertebral pneumaticity in sauropod dinosaurs. Journal of Vertebrate Paleontology 23:344-357.
- Wedel, M.J. 2007. Aligerando a los gigantes (Lightening the giants). ¡Fundamental! 12:1-84. [in Spanish, with English translation]
- Wedel, M.J., and Cifelli, R.L. 2005. Sauroposeidon: Oklahoma’s native giant. Oklahoma Geology Notes 65 (2):40-57.
- Wedel, M.J., R.L. Cifelli and R.K. Sanders. 2000. Osteology, paleobiology, and relationships of the sauropod dinosaur Sauroposeidon. Acta Palaeontologica Polonica 45(4): 343-388.
November 3, 2013
As I mentioned a few days ago, Matt and I have a couple of papers in the new PLOS ONE Sauropod Gigantism collection. We were each lead author on one and second author on the other, so for convenience’s sake we’ll refer to them as my paper (Taylor and Wedel 2013c on neck cartilage) and Matt’s paper (Wedel and Taylor 2013b on caudal pneumaticity.)
Mine is very simple in concept (although it ended up at 17 pages and 23 figures). It’s all about addressing one of the overlooked variables in reconstructing the postures of the necks of sauropods (and indeed of all tetrapods). That is, the spacing between consecutive vertebrae, and the effect this has on “neutral pose”.
The concept of “neutral pose” goes back to the DinoMorph work of Stevens and Parrish (1999). They defined it (p. 799) as follows: “We determined the neutral poses for each animal, wherein the paired articular facets of the postzygapophyses of each cervical vertebra were centered over the facets of the prezygapophyses of its caudally adjacent counterpart.”
One of the more fundamental flaws in Stevens and Parrish (1999) is the assumption that animals habitually rest their necks in neutral pose — an assumption that is unsupported by evidence and, as it turns out, false (Vidal et al. 1986, Taylor et al. 2009). But let’s leave that aside for the moment, and consider what neutral pose actually represents.
The fact that there is even such a thing as neutral articulation between two consecutive vertebrae is due to there being three points of contact between those vertebra: as with the legs of a tripod, three points is the minimum number you need to fix an object in three-dimensional space. Two of these points are at the zygapophyses, as noted in the original definition above. The third point is the articulation between the centra.
The centrum has been curiously overlooked in discussions of neutral pose, but needless to say its length is crucial in establishing what is neutral. In the image above, if the centrum was longer, then the angle between the consecutive vertebrae would need to be raised in order to keep the zygapophyses articulated.
And of course it was longer in life, because of the cartilage in between the consecutive centra. (The use of the more specific term “osteological neutral pose” goes some way to recognising that tissues other than bone have been overlooked, but the problem has not really been addressed or even properly acknowledged in published works before our paper.)
You simply can’t ignore cartilage when modelling neck postures and expect to get anything resembling a meaningful result. That is, presumably, the reason why the habitual posture of rabbits in life exceeds the most extended posture we were able to obtain when manipulating dry vertebrae of a hare: compare Vidal et al. (1986: fig. 4) with Taylor et al. (2009: fig. 1).
How big is the effect? That depends on the thickness of the cartilage and the height of the zygapophyses above the center of rotation. Here is an illustration that we should have put in the paper, but which inexplicably neither of us thought of:
Here’s some elementary trigonometry. Suppose the intervertebral cartilage is x distance thick at mid-height of the centra, and that the height of the zygs above this mid-height point (the magenta line) is y. The triangle between the middle of the condyle of the posterior vertebra, the middle of the cotyle of the anterior one and the zygapophyseal articulation is near enough a right-angled triangle as makes no odds.
Consider the angle θ between the green lines. Sin(θ) = opposite/hypotenuse = x/y, and by similarity, the additional angle of inclination of the anterior vertebra is also θ.
But for small angles (and this is generally a small angle), sin(θ) ≈ θ. So the additional inclination in radians = cartilage thickness divided by zygapophyseal height. For example, in vertebrae where the zygs are 23 cm above the mid-height of the centra, adding 4 cm of intervertebral cartilage adds about 4/23 = 0.174 radians = 10 degrees of extra inclination. (That’s pretty similar to the angle in the illustration above. Eyeballing the cartilage thickness and zyg height in the illustration suggests that 23:4 ratio is about right, which is a nice sanity-check of this method.)
At this point, I am cursing my own stupidity for not putting this diagram, and the very simple calculation, into the paper. I guess that can happen when something is written in a hurry (which to be honest this paper was). The formula is so simple — and accurate enough within tolerances of inevitable measurement error — that we really should have used it all over the place. I guess that will have to go in a followup now. [Update, 5th November 2014. It’s long overdue, but that followup paper has finally been submitted and is available as a preprint.]
Anyway — next time, we’ll address this important related question: how thick, in fact, was the cartilage between the cervicals of sauropods?
- Stevens, Kent A., and J. Michael Parrish. 1999. Neck Posture and Feeding Habits of Two Jurassic Sauropod Dinosaurs. Science 284:798-800.
- Taylor, Michael P., and Matthew J. Wedel. 2013c. The effect of intervertebral cartilage on neutral posture and range of motion in the necks of sauropod dinosaurs. PLOS ONE 8(10): e78214. 17 pages. doi:10.1371/journal.pone.0078214 [PDF]
- Taylor, Michael P., Mathew J. Wedel and Darren Naish. 2009. Head and neck posture in sauropod dinosaurs inferred from extant animals. Acta Palaeontologica Polonica 54(2):213-230. [PDF]
- Vidal, Pierre Paul, Werner Graf and Alain Berthoz. 1986. The orientation of the cervical vertebral column in unrestrained awake animals. Experimental Brain Research, 61:549-559. doi:10.1007/BF00237580
- Wedel, Mathew J., and Michael P. Taylor. 2013. Caudal pneumaticity and pneumatic hiatuses in the sauropod dinosaurs Giraffatitan and Apatosaurus. PLOS ONE 8(10):e78213. 14 pages. doi:10.1371/journal.pone.0078213 [PDF]
April 4, 2013
Because I am preparing this paper from PLOS ONE, with its stupid numbered-references system, I am finally getting to grips with a reference-management system. Specifically, Zotero, which is both free and open source, which means it can’t be taken over by Elsevier.
As a complete Zotero n00b, I’ve run into a few issues that more experienced users will no doubt find laughable. Here are two of them. I need to cite Greg Paul’s classic 1988 paper on the skeletal reconstruction of Giraffatitan:
Paul, Gregory S. 1988. The brachiosaur giants of the Morrison and Tendaguru with a description of a new subgenus, Giraffatitan, and a comparison of the world’s largest dinosaurs. Hunteria 2(3):1-14.
When I render this using Zotero’s PLOS ONE style, it comes out as:
Paul GS (1988) The brachiosaur giants of the Morrison and Tendaguru with a description of a new subgenus, Giraffatitan, and a comparison of the world’s largest dinosaurs. Hunteria 2: 1–14.
So the first problem is, how can I get Giraffatitan to be set in italics?
And the second one, which is arguably more important, is how can I get the issue number included? I undertsand that PLOS ONE referencing style omits the issue-numbers by preference, since they are often redundant, with the pages of each volume being numbered consecutively across volumes. But Hunteria is one of those journals (PaleoBios is another) that resets page-numbers at the start of each issue. As a result, Hunteria volume 2 had at least three page 14s, one in each of its issues, so that issue number is a crucial part of the reference.
Help me, SV-POW! readers — you’re my only hope.
April 28, 2012
Given the huge amount we’ve written about open access on this blog, it may come as a surprise to realise that the blog itself has not been open access until today. It’s been free to read, of course, but in the absence of an explicit licence statement, the default “all rights reserved” has applied, which has meant that technically you’re not supposed to do things like, for example, using SV-POW! material in course notes.
It was never our intention to be so restrictive, of course. We always wanted what we write to be as widely useful as possible; but like most bloggers, we just didn’t think about what that entailed.
So now, belatedly, we are placing SV-POW! under the Creative Commons Attribution licence. This means that you can do anything with our content, subject only to giving us credit. Go nuts. We want our work to be useful. (Our use of this licence is indicated by the CC BY button at top right of all the pages.)
Note that SV-POW! is now compliant with the Budapest Open Access Initiative’s definition of open access — the only definition that matters, really, since it’s where the term “open access” was first coined. That definition is rather noble and striking:
By ‘open access’ to this literature, we mean its free availability on the public internet, permitting any users to read, download, copy, distribute, print, search, or link to the full texts of these articles, crawl them for indexing, pass them as data to software, or use them for any other lawful purpose, without financial, legal, or technical barriers other than those inseparable from gaining access to the internet itself. The only constraint on reproduction and distribution, and the only role for copyright in this domain, should be to give authors control over the integrity of their work and the right to be properly acknowledged and cited.”
We are applying this licence restrospectively to all the original content on the site — not just what we write from now on. To ensure that we’re on safe ground doing this, all three of us agreed on this measure, and we also obtained consent from the only (so far) guest-blogger on SV-POW!, Heinrich Mallison.
Finally, we should note the exceptions to the CC BY licence. When we’ve included material from other sources — most often figures from published papers — we do not own the copyright and can’t licence it. Similarly, all photographs of fossils held by the Natural History Museum in London are copyright the museum. If you want to re-use any of the non-original material, you’ll need to track down the copyright holders and negotiate with them.