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The links in the first slide:

Mike’s post on desaturating the background in specimen photos is here, and previous posts in this series are here.

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Previous posts in this series are here.

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Previous posts in this series:

Part 1: Intro and Stromer

Part 2: Taking good photos

Part 3: Backdrops and lighting

And the rest of the series is here.

Today (12th February) is the one-year anniversary of the first PeerJ papers! As Matt put it in an email this morning:

Hard to believe it’s been a year already. On the other hand, it’s also hard to believe that it’s only been a year. PeerJ is just such an established part of my worldview now.

That’s exactly right. PeerJ has so completely rewritten the rule-book (on price, speed and quality of service) that now when I’m thinking about new papers I’m going to write, the question I ask myself is no longer “Where shall I send this?” but “Is there any reason not to send it to PeerJ?”

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Dorsals A and B (probably D8 and D9) of NHM R5937, “The Archbishop”, a still-undescribed brachiosaurid sauropod from the Upper Jurassic Tendaguru Formation of Tanzania, which I will get done this year, and which is destined for PeerJ. Top row: dorsal view with anterior to the right. Bottom row, from left to right: left lateral, posterior, right lateral, anterior.

Yesterday in the comments of a post on The Scholarly Kitchen, Harvey Kane asked me “I am curious as to where you get the notion that publishing OA is less expensive and in some way “better” than the traditional model?” My reply was (in part):

My notion that OA publishing yields better results than traditional is rooted in the online-only nature of articles, which allows them to ignore arbitrary limits on word-count, number of figures, use of colour, etc., and to exploit online-only formats such as video, 3d models, CT-slice stacks, etc. In my own field of vertebrate palaeontology, it’s now routine to see in PLOS ONE descriptive articles that are many times more comprehensive than their equivalents in traditional journals — see for example the recent description of the frog Beelzebufo.

Of course there is nothing specific to open-access about this: there is no technical reason why an online-only subscription journal shouldn’t publish similarly detailed articles. But my experience so far has been that they don’t — perhaps because they are tied to the mindset that pages and illustrations are limited resources.

For Beelzebufo in PLOS ONE, read baby Parasaurolophus in PeerJ, which we described as “the world’s most open-access dinosaur“. This paper is 83 pages of technicolour goodness, plus all the 3d models you can eat. And the crazy thing is, this sort of detail in descriptive papers is not even exceptional any more — see for example the recent description of Canardia in PLOS ONE, or this analysis of croc respiration in PeerJ

Years ago, I said that in the Archbishop descriptions I wanted to raise the bar for quality of illustration. Well, I’ve taken so long over getting the Archbishop done that the bar has been raised, and now I’m scrambling to catch up. Certainly the illustrations even in our 2011 description of Brontomerus are starting to look a bit old-fashioned.

And of course, the truly astonishing thing about PeerJ is that it does this so very cheaply. Because I’m already a member (which cost me $99), the Archbishop description is going to be free to me to publish this year. (This year for sure!) If we also get our Barosaurus neck preprint published properly this year,then I’ll have to find $100 to upgrade my Basic membership to Enhanced. That’s cheap enough that it’s not even worth going through the hassle of trying to get Bristol to pay for me. And if I ever hit a year when I publish three or more papers, I’ll upgrade once more (for another $100) to the Investigator plan and then that’s it: I’m done paying PeerJ forever, however many papers I publish there. (Matt jumped straight to the all-you-can-eat plan, so he wouldn’t even have to think about it ever again.)

Barosaurus lentus holotype YPM 429, Vertebra Q (C?13). Top row: left ventrolateral view. Middle row, from left to right: anterior view, with ventral to the right; ventral view; posterior view, with ventral to the left. Bottom row: right lateral view, inverted. Inset shows diapophyseal facet on right side of vertebra, indicating that the cervical ribs were unfused in this individual despite its great size. Note the broad, flat prezygapophyseal facet visible in anterior view. (Taylor and Wedel 2013b: figure 6)


Barosaurus lentus holotype YPM 429, Vertebra Q (C?13). Top row: left ventrolateral view. Middle row, from left to right: anterior view, with ventral to the right; ventral view; posterior view, with ventral to the left. Bottom row: right lateral view, inverted. Inset shows diapophyseal facet on right side of vertebra, indicating that the cervical ribs were unfused in this individual despite its great size. Note the broad, flat prezygapophyseal facet visible in anterior view. (Taylor and Wedel 2013b: figure 6)

PeerJ’s pricing is making PLOS ONE’s $1350 APC look distinctly old-fashioned; and the $3000 charged by the legacy publishers (for a distinctly inferior product) is now frankly embarrassing. You might expect that as such low prices, PeerJ’s quality of service would suffer, but that’s not been our experience: editing, reviewing, typesetting and proofing for our neck-anatomy paper were all up there with the best we’ve received anywhere.

And it’s great to see that it’s not just minor researchers like Matt and me who are persuaded by PeerJ: they’ve now accumulated a frankly stellar list of 20 universities (so far) with institutional plans for researchers to publish there. When I say “stellar” I mean that the list includes Harvard, MIT, Cambridge, Berkeley, Stanford, Johns Hopkins, UCL, Carnegie Mellon, Duke … the list goes on.

We can only hope that the next year, and the next ten and twenty, are as successful for PeerJ as the first has been; and that other New Generation publishers will join it in pushing the field forward.

I leave the last word to Matt:

I’m getting Vicki a lifetime membership for Valentine’s Day. Because I’m a romantic.

She’s a lucky, lucky woman.

“Look at all the things you’ve done for me
Opened up my eyes,
Taught me how to see,
Notice every tree.”

So sings Dot in Move On, the climactic number of Stephen Sondheim’s Pulitzer Prize-winning music Sunday in the Park with George, which on the surface is about the post-impressionist painter Georges Seurat, but turns out to be a study of obsession and creativity.

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Un dimanche après-midi à l’Île de la Grande Jatte – 1884 [A Sunday Afternoon on the Island of La Grande Jatte – 1884]

“Taught me how to see”? What kind of talk is that? One the surface, it seems silly — we all know how to see. We do it constantly, without thinking. Yet it’s something that artists talk about all the time. And anyone who’s sat down and seriously tried to paint or draw something will have some understanding of what the phrase means. We have such strong implicit ideas of what things look like that we tend to reproduce what we “know” is there rather than what’s actually there. Like I said, we see without thinking.

In fact, the psychology of perception is complicated and sophisticated, and the brain does an extraordinary amount of filtering of the visual signals we get, to save us the bother of having to consciously process way too much data. This is a whole scientific field of its own, and I’m going to avoid saying very much about it for fear of making a fool of myself — as scientists so often do when wandering outside their own field. But I think it’s fair to say that we all have a tendency to see what we expect to see.

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Phylogeny of Sauropoda, strict consensus of most parsimonious trees according to Wilson (2002:fig. 13a)

In the case of sauropods, this tendency has meant that we’ve all been startlingly bad at seeing pneumaticity in the caudal vertebrae of sauropods. Because the literature has trained us to assume it’s not there. For example, in the two competing sauropod phylogenies that dominated the 2000s, both Wilson (2002) and Upchurch et al. (2004) scored caudal pneumaticity as very rare: Wilson’s character 119, “Anterior caudal centra, pneumatopores (pleurocoels)”, was scored 1 only for Diplodocus and Barosaurus; and  Upchurch et al. (2004:286) wrote that “A few taxa (Barosaurus, Diplodocus, and Neuquensaurus) have pleurocoel-like openings in the lateral surfaces of the cranial [caudal] centra that lead into complex internal chambers”. That’s all.

And that’s part of the reason that every year since World War II, a million people have walked right past the awesome mounted brachiosaur in the Museum Für Naturkunde Berlin without noticing that it has pneumatic caudals. After all, we all knew that brachiosaur caudals were apneumatic.

But in my 2005 Progressive Palaeontology talk about upper limits on the mass of land animals estimated through the articular area of limb-bone cartilage, I included this slide that shows how much bigger the acetabulum of Giraffatitan is than the femoral head that it houses:

Screenshot from 2014-01-24 17:30:30

And looking at that picture made me wonder: those dark areas on the sides of the first few caudals (other than the first, which is a very obvious plaster model) certainly look pneumatic.

Then a few years later, I was invited to give a talk at the Museum Für Naturkunde Berlin itself, on the subject “Brachiosaurus brancai is not Brachiosaurus“. (This of course was drawn from the work that became my subsequent paper on that subject, Taylor 2009) And as I was going through my photos to prepare the slides of that talk, I thought to myself: darn it, yes, it does have pneumatic caudals!

So I threw this slide into the talk, just in passing:

Screenshot from 2014-01-24 17:32:06

Those photos were pretty persuasive; and a closer examination of the specimen on that same trip was to prove conclusive.

Meanwhile …

Earlier in 2009, I’d been in Providence, Rhode Island, with my Index Data colleagues. I’d managed to carve a day out of the schedule to hope along the coast to the Yale Peabody Museum in New Haven, Connecticut. My main goal was to examine the cervicals of the mounted Apatosaurus (= “Brontosaurus“) excelsus holotype (although it was also on that same trip that I first saw the Barosaurus holotype material that we’ve subsequently published a preprint on).

The Brontosaurus cervicals turned out to be useless, being completely encased in plaster “improvements” so that you can’t tell what’s real and what’s not. hopefully one day they’ll get the funding they want to take that baby down off its scaffold and re-prep the material.

But since I had the privilege of spending quality time with such an iconic specimen, it would have been churlish not to look at the rest of it. And lo and behold, what did I see when I looked at the tail but more pneumaticity that we thought we knew wasn’t there!

Wedel and Taylor (2013b: Figure 10).

An isolated pneumatic fossa is present on the right side of caudal vertebra 13 in Apatosaurus excelsus holotype YPM 1980. The front of the vertebra and the fossa are reconstructed, but enough of the original fossil is visible to show that the feature is genuine. (Wedel and Taylor 2013b: Figure 10).

What does this mean? Do other Giraffatitan and Apatosaurus specimens have pneumatic tails? How pervasive is the pneumaticity? What are the palaeobiological implications?

Stay tuned! All will be revealed in Matt’s next post (or, if you can’t wait, in our recent PLOS ONE paper, Wedel and Taylor 2013b)!

References

[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.]

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Weird stuff on the ground, Big Bend, 2007.

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!”

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Kent Sanders looking at scans of BYU 12613, a posterior cervical of either Kaatedocus or an anomalously small Diplodocus, at the University of Utah in May, 2008.

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.

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BYI 12613 going through a CT scanner at the University of Utah medical center. We were filming for the “Megasaurus” episode of Jurassic CSI. That shoot was crazy fun.

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.

Sauroposeidon C5 cross section Wedel 2007b fig 14

Internal structure of a cervical vertebra of Sauroposeidon, OMNH 53062. A, parts of two vertebrae from the middle of the neck. The field crew that dug up the bones cut though one of them to divide the specimen into manageable pieces. B, cross section of C6 in posterior view at the level of the break, traced from a CT image and photographs of the broken end. The left side of the specimen was facing up in the field and the bone on that side is badly weathered. Over most of the broken surface the internal structure is covered by plaster or too damaged to trace, but it is cleanly exposed on the upper right side (outlined). C, the internal structure of that part of the vertebra, traced from a photograph. The arrows indicate the thickness of the bone at several points, as measured with a pair of digital calipers. The camellae are filled with sandstone. Wedel (2007: fig. 14).

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.

Figure 11. Fifth and partial sixth cervical vertebrae of Sauroposeidon. Photograph and x-ray scout image of C5 and the anterior portion of C6 of Sauroposeidon OMNH 53062 in right lateral view. The anterior third of C5 eroded away before the vertebra was collected. C6 was deliberately cut through in the field to break the multi-meter specimen into manageable pieces for jacketing (see [37] for details). Note that the silhouettes of the cotyle of C5 and the condyle of C6 are visible in the x-ray.

Fifth and partial sixth cervical vertebrae of Sauroposeidon.
Photograph and x-ray scout image of C5 and the anterior portion of C6 of Sauroposeidon OMNH 53062 in right lateral view. The anterior third of C5 eroded away before the vertebra was collected. C6 was deliberately cut through in the field to break the multi-meter specimen into manageable pieces for jacketing (see Wedel and Cifelli 2005 for details). Note that the silhouettes of the cotyle of C5 and the condyle of C6 are visible in the x-ray. Taylor and Wedel (2013: figure 11).

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.

Figure 12. CT slices from fifth cervical vertebrae of Sauroposeidon. X-ray scout image and three posterior-view CT slices through the C5/C6 intervertebral joint in Sauroposeidon OMNH 53062. In the bottom half of figure, structures from C6 are traced in red and those from C5 are traced in blue. Note that the condyle of C6 is centered in the cotyle of C5 and that the right zygapophyses are in articulation.

CT slices from fifth cervical vertebrae of Sauroposeidon.
X-ray scout image and three posterior-view CT slices through the C5/C6 intervertebral joint in Sauroposeidon OMNH 53062. In the bottom half of figure, structures from C6 are traced in red and those from C5 are traced in blue. Note that the condyle of C6 is centered in the cotyle of C5 and that the right zygapophyses are in articulation. Taylor and Wedel (2013: figure 12).

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.

Figure 14. Geometry of opisthocoelous intervertebral joints. Hypothetical models of the geometry of an opisthocoelous intervertebral joint compared with the actual morphology of the C5/C6 joint in Sauroposeidon OMNH 53062. A. Model in which the condyle and cotyle are concentric and the radial thickness of the intervertebral cartilage is constant. B. Model in which the condyle and cotyle have the same geometry, but the condyle is displaced posteriorly so the anteroposterior thickness of the intervertebral cartilage is constant. C. the C5/C6 joint in Sauroposeidon in right lateral view, traced from the x-ray scout image (see Figure 12); dorsal is to the left. Except for one area in the ventral half of the cotyle, the anteroposterior separation between the C5 cotyle and C6 condyle is remarkably uniform. All of the arrows in part C are 52 mm long.

Geometry of opisthocoelous intervertebral joints.
Hypothetical models of the geometry of an opisthocoelous intervertebral joint compared with the actual morphology of the C5/C6 joint in Sauroposeidon OMNH 53062. A. Model in which the condyle and cotyle are concentric and the radial thickness of the intervertebral cartilage is constant. B. Model in which the condyle and cotyle have the same geometry, but the condyle is displaced posteriorly so the anteroposterior thickness of the intervertebral cartilage is constant. C. the C5/C6 joint in Sauroposeidon in right lateral view, traced from the x-ray scout image (see Figure 12); dorsal is to the left. Except for one area in the ventral half of the cotyle, the anteroposterior separation between the C5 cotyle and C6 condyle is remarkably uniform. All of the arrows in part C are 52 mm long. Taylor and Wedel (2013: figure 14).

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.

Figure 13. Joint between sixth and seventh cervicals vertebrae of Sauroposeidon. X-ray scout image of the C6/C7 intervertebral joint in Sauroposeidon OMNH 53062, in right lateral view. The silhouette of the condyle is traced in blue and the cotyle in red. The scale on the right is marked off in centimeters, although the numbers next to each mark are in millimeters.

Joint between sixth and seventh cervicals vertebrae of Sauroposeidon.
X-ray scout image of the C6/C7 intervertebral joint in Sauroposeidon OMNH 53062, in right lateral view. The silhouette of the condyle is traced in blue and the cotyle in red. The scale on the right is marked off in centimeters, although the numbers next to each mark are in millimeters. Taylor and Wedel (2013: figure 13).

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.

Figure 15. First and second dorsal vertebrae of Apatosaurus CM 3390. Articulated first and second dorsal vertebrae of Apatosaurus CM 3390. A. Digital model showing the two vertebrae in articulation, in left lateral (top) and ventral (bottom) views. B-G. Representative slices illustrating the cross-sectional anatomy of the specimen, all in posterior view. B. Slice 25. C. Slice 31. D. Slice 33. E. Slice 37. F. Slice 46. G. Slice 61. Orthogonal gaps are highlighted where the margins of the condyle and cotyle are parallel to each other and at right angles to the plane of the CT slice. 'Zygs' is short for 'zygapophyses', and NCS denotes the neurocentral synchondroses.

First and second dorsal vertebrae of Apatosaurus CM 3390.
Articulated first and second dorsal vertebrae of Apatosaurus CM 3390. A. Digital model showing the two vertebrae in articulation, in left lateral (top) and ventral (bottom) views. B-G. Representative slices illustrating the cross-sectional anatomy of the specimen, all in posterior view. B. Slice 25. C. Slice 31. D. Slice 33. E. Slice 37. F. Slice 46. G. Slice 61. Orthogonal gaps are highlighted where the margins of the condyle and cotyle are parallel to each other and at right angles to the plane of the CT slice. ‘Zygs’ is short for ‘zygapophyses’, and NCS denotes the neurocentral synchondroses. Taylor and Wedel (2013: figure 15).

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.

Figure 16. Dorsal vertebrae of Apatosaurus CM 11339. Articulated middle or posterior dorsal vertebrae of Apatosaurus CM 11339. A. X-ray scout image showing the two vertebrae in articulation, in left lateral view. B–D. Slices 39, 43 and and 70 in posterior view, showing the most anterior appearance of the condyles and cotyles.

Dorsal vertebrae of Apatosaurus CM 11339.
Articulated middle or posterior dorsal vertebrae of Apatosaurus CM 11339. A. X-ray scout image showing the two vertebrae in articulation, in left lateral view. B–D. Slices 39, 43 and and 70 in posterior view, showing the most anterior appearance of the condyles and cotyles. Taylor and Wedel (2013: figure 16).

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.

References

A few bits and pieces about the PLOS Collection on sauropod gigantism that launched yesterday.

2013-10-29-SauropodEbook1-thumb

First, there’s a nice write-up of one of our papers (Wedel and Taylor 2013b on pneumaticity in sauropod tails) in the Huffington Post today. It’s the work of PLOS blogger Brad Balukjian, a former student of Matt’s from Berkeley days. The introduction added by the PLOS blogs manager is one of those where you keep wanting to interrupt, “Well, actually it’s not quite like that …” but the post itself, once it kicks in, is good. Go read it.

Brad also has a guest-post on Discover magazine’s Crux blog: How Brachiosaurus (and Brethren) Became So Gigantic. He gives an overview of the sauropod gigantism collection as a whole. Well worth a read to get your bearings on the issue of sauropod gigantism in general, and the new collection in particular.

PLOS’s own community blog EveryONE also has its own brief introduction to the collection.

And PLOS and PeerJ editor Andy Farke, recently in these pages because of his sensational juvenile Parasaurolophus paper, contributes his own overview of the collection, How Big? How Tall? And…How Did It Happen?

Finally, if you’re at SVP, go and pick up your free copy of the collection. Matt was somehow under the impression that the PLOS USB drives with the sauropod gigantism collection would be distributed with the conference packet when people registered. In fact, people have to go by the PLOS table in the exhibitor area (booth 4 in the San Diego ballroom) to pick them up. There are plenty of them, but apparently a lot of people don’t know that they can get them.

References

This is an exciting day: the new PLOS Collection on sauropod gigantism is published to coincide with the start of this year’s SVP meeting! Like all PLOS papers, the contents are free to the world: free to read and to re-use.  (What is a Collection? It’s like an edited volume, but free online instead of printed on paper.)

There are fourteen papers in the new Collection, encompassing neck posture (yay!), nutrition (finally putting to bed the Nourishing Vomit Of Eucamerotus hypothesis), locomotion, physiology and evolutionary ecology. Lots every sauropod-lover to enjoy.

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Taylor and Wedel (2013c: Figure 12). CT slices from fifth cervical vertebrae of Sauroposeidon. X-ray scout image and three posterior-view CT slices through the C5/C6 intervertebral joint in Sauroposeidon OMNH 53062. In the bottom half of figure, structures from C6 are traced in red and those from C5 are traced in blue. Note that the condyle of C6 is centered in the cotyle of C5 and that the right zygapophyses are in articulation.

Matt and I are particularly excited that we have two papers in this collection: Taylor and Wedel (2013c) on intervertebral cartilage in necks, and Wedel and Taylor (2013b) on pneumaticity in the tails of (particularly) Giraffatitan and Apatosaurus. So we have both ends of the animal covered. It also represents a long-overdue notch on our bed-post: for all our pro-PLOS rhetoric, this is the first time either of has had a paper published in a PLOS journal.

Wedel and Taylor (2013b: Figure 4). Giraffatitan brancai tail MB.R.5000 (‘Fund no’) in right lateral view. Dark blue vertebrae have pneumatic fossae on both sides, light blue vertebrae have pneumatic fossae only on the right side, and white vertebrae have no pneumatic fossae on either side. The first caudal vertebra (hatched) was not recovered and is reconstructed in plaster.

It’s a bit of a statistical anomaly that after a decade of collaboration in which there was never a Taylor & Wedel or Wedel & Taylor paper, suddenly we have five of them out in a single year (including the Barosaurus preprint, which we expect to eventually wind up as Taylor and Wedel 2014). Sorry about the alphabet soup.

Since Matt is away at SVP this week, I’ll be blogging mostly about the Taylor and Wedel paper this week. When Matt returns to civilian life, the stage should be clear for him to blog about pneumatic caudals.

Happy days!

References

Yesterday I announced that our new paper on Barosaurus was up as a PeerJ preprint and invited feedback.

I woke up this morning to find its third substantial review waiting for me.

That means that this paper has now accumulated as much useful feedback in the twenty-seven hours since I submitted it as any previous submission I’ve ever made.

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Taylor and Wedel (2013b: figure 7). Barosaurus lentus holotype YPM 429, Vertebra S (C?12). Left column from top to bottom: dorsal, right lateral and ventral views; right column: anterior view. Inset shows displaced fragment of broken prezygapophysis. Note the narrow span across the parapophyses in ventral view, and the lack of damage to the ventral surface of the centrum which would indicate transverse crushing.

It’s worth reviewing the timeline here:

  • Monday 23rd September, 1:19 am: I completed the submission process.
  • 7:03 am: the preprint was published. It took less than six hours.
  • 10:52 am: received a careful, detailed review from Emanuel Tschopp. It took less than four hours from publication, and so of course less than ten from submission.
  • About 5:00 pm: received a second review, this one from Mark Robinson. (I don’t know the exact time because PeerJ’s page doesn’t show an actual timestamp, just “21 hours ago”.)
  • Tuesday 24th September, about 4:00 am: received a third review, this from ceratopsian-jockey and open-science guru Andy Farke.

Total time from submission to receiving three substantial reviews: about 27 hours.

It’s worth contrasting that with the times taken to get from submission to the receipt of reviews — usually only two of them — when going through the traditional journal route. Here are a few of mine:

  • Diplodocoid phylogenetic nomenclature at the Journal of Paleontology, 2004-5 (the first reviews I ever received): three months and 14 days.
  • Revised version of the same paper at PaleoBios, 2005 (my first published paper): one month and 10 days.
  • Xenoposeidon description at Palaeontology, 2006: three months and 19 days, although that included a delay as the handling editor sent it to a third, tie-breaking, reviewer.
  • Brachiosaurus revision at the Journal of Vertebrate Paleontology, 2008: one month and 11 days.
  • Sauropod neck anatomy (eventually to be published in a very different form in PeerJ) at Paleobiologyfive months and two days.
  • Trivial correction to the Brachiosaurus revision at the Journal of Vertebrate Paleontology, 2010: five months and 11 days, bizarrely for a half-page paper.

Despite the wide variations in submission-to-review time at these journals, it’s clear that you can expect to wait at least a month before getting any feedback at all on your submission at traditional journals. Even PeerJ took 19 days to get the reviews of our neck-anatomy paper back to us.

So I am now pretty such sold on the pre-printing route. As well as getting this early version of the paper out there early so that other palaeontologists can benefit from it (and so that we can’t be pre-emptively plagiarised), issuing a preprint has meant that we’ve got really useful feedback very quickly.

I highly recommend this route.

By the way, in case anyone’s wondering, PeerJ Preprints is not only for manuscripts that are destined for PeerJ proper. They’re perfectly happy for you to use their service as a place to gather feedback for your work before submitting it elsewhere. So even if your work is destined for, say, JVP, there’s a lot to be gained by preprinting it first.

I was very pleased, on checking my email this morning, to see that my and Matt’s new paper, The neck of Barosaurus was not only longer but also wider than those of Diplodocus and other diplodocines, is now up as a PeerJ preprint!

Figure6-vertebra-q-composite

Taylor and Wedel (2013b: figure 6). Barosaurus lentus holotype YPM 429, Vertebra Q (C?13). Top row: left ventrolateral view. Middle row, from left to right: anterior view, with ventral to the right; ventral view; posterior view, with ventral to the left. Bottom row: right lateral view, inverted. Inset shows diapophyseal facet on right side of vertebra, indicating that the cervical ribs were unfused in this individual despite its great size. Note the broad, flat prezygapophyseal facet visible in anterior view.

I was pleased partly because of the very quick work on PeerJ’s part. I submitted the preprint at 1:22am last night, then went to bed. Almost immediately I got an automatic email from PeerJ saying:

Thank you for submitting your manuscript, “The neck of Barosaurus was not only longer but also wider than those of Diplodocus and other diplodocines” (#2013:09:838:0:0:CHECK:P) – it has now been received by PeerJ PrePrints.

Next, it will be checked by PeerJ staff, who will notify you if any alterations are required to the manuscript or accompanying files.

If the PrePrint successfully passes these checks, it will be made public.

You will receive notification by email at each stage of this process; you can also check the status of your manuscript at any time.

Lots to like here: the quickness of the response, the promise of automatic email updates, and the one-click link to check on progress (as opposed to the usual maze of Manuscript Central options to navigate).

Sure enough, a couple of hours later the next automatic email arrived, telling me that Matt had accepted PeerJ’s email invitation to be recognised as the co-author of the submission.

And one hour ago, just as I was crawling out of bed, I got the notification that the preprint is up. That simple.

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Taylor and Wedel (2013b: Figure 9). Partial reconstruction of the Barosaurus lentus holotype YPM 429, cervical vertebra R, approximating its undamaged state by allowing for dorsoventral crushing, shearing and loss of some extremities. Anterior and posterior views scaled to 125% of uncorrected width and 80% of uncorrected height. Dorsal view scaled to 80% of uncorrected height; condyle moved forward and cotyle scaled to 50% of uncorrected width to allow for shearing. Lateral view scaled to 125% of uncorrected height, and sheared backwards 15 degrees. Metapophyses and postzygapophyses drawn in multiple views based on vertebrae Q and S and AMNH 6341 material.

I’m also pleased because we managed to get this baby written so quickly. It started life as our talk at SVPCA in Edinburgh (Taylor and Wedel 2013a), which we delivered 25 days ago having put it together mostly in a few days running up to the conference — so it’s zero to sixty in less than a month. Every year we promise ourselves that we’ll write up our talks, and we never seem to get around to it, but this year I started writing on the train back from Edinburgh. By the time I got home I had enough of a hunk of text to keep me working on it, and so we were able to push through in what, for us, is record time.

Now here’s what we’d like:

We want this paper’s time as a preprint to be time well spent — which means that we want to improve it. To do that, we need your reviews. Assuming we get some useful comments, we plan to release an updated version pretty soon; and after some number of iterations, we’ll submit the resulting paper as a full-fledged PeerJ paper.

So if you know anything about sauropods, about vertebra, about deformation, about ecology, or even about grammar or punctuation, please do us a favour: read the preprint, then get over to its PeerJ page and leave your feedback. You’ll be helping us to improve the scientific record. We’ll acknowledge substantial comments in the final paper, but even the pickiest comments are appreciated.

Because we want to encourage this approach to bringing papers to publication, we’d ask you please do not post comments about the paper here on SV-POW!. Please post them on the PeerJ preprint page. We’ve leaving comments here open for discussion of the preprinting processes, but not the scientific content.

References

  • Taylor, Michael P., and Mathew J. Wedel. 2013a. Barosaurus revisited: the concept of Barosaurus (Dinosauria: Sauropoda) is based on erroneously referred specimens. (Talk given as: Barosaurus revisited: the concept of Barosaurus (Dinosauria: Sauropoda) is not based on erroneously referred specimens.) pp. 37-38 in Stig Walsh, Nick Fraser, Stephen Brusatte, Jeff Liston and Vicen Carrió (eds.), Programme and Abstracts, 61st Symposium on Vertebrae Palaeontology and Comparative Anatomy, Edinburgh, UK, 27th-30th August 2013. 33 pp.
  • Taylor, Michael P., and Mathew J. Wedel. 2013b. The neck of Barosaurus was not only longer but also wider than those of Diplodocus and other diplodocines. PeerJ PrePrints 1:e67v1 http://dx.doi.org/10.7287/peerj.preprints.67v1
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