Anatomical features of the neural canal in birds and other dinosaurs. A. MWC 9698, a mid caudal vertebra of Apatosaurus in posterodorsal view. Arrows highlight probable vascular foramina in the ventral floor of the neural canal. B. LACM 97479, a dorsal vertebra of Rhea americana in left anterolateral view. Arrows highlight pneumatic foramina inside the neural canal. C. A hemisected partial synsacrum of a chicken, Gallus domesticus, obtained from a grocery store. Anterior is to the right. The bracket shows the extent of the dorsal recess for the glycogen body, which only spans four vertebrae. Arrows highlight the transverse grooves in the roof of the neural canal for the lumbosacral organ. D. Sagittal (left) and transverse (right) CT slices through the sacrum of a juvenile ostrich, Struthio camelus. The bracket shows the extent of the lumbosacral expansion of the spinal cord. Indentations in the roof of the neural canal house the lumbosacral organ. In contrast to the chicken, the ostrich has a small glycogen body that does not leave a distinct osteological trace. Yellow arrows show the longitudinal troughs in the ventral floor of the neural canal that house the ventral eminences of the spinal cord. Wedel et al. (2021: fig. 4).

This is the second in a series of posts on our new paper about the expanded neural canals in the tail vertebrae of the Snowmass Haplocanthosaurus. I’m not going to talk much about Haplo in this post, though. Instead, I’m going to talk about chickens, and about how you can see a lot of interesting spinal anatomy in a living dinosaur for about two bucks.

You know by now that Academia Letters publishes peer reviews, which is one of the things that drew me to this fairly new journal. More on that in a later post, but in the meantime, the peer reviews for the Haplo paper are on the right sidebar here. I confess, I had a total forehead-slap moment when I read the opening lines of Niels Bonde’s review: 

This paper is interesting, and should be published and discussed by others with interest in dinosaur-bird relations. However, as these publications are also meant for the general public, I would recommend that 2 – 3 illustrations were added of the features mentioned for birds under nos. 3 – 6, because the general public (and many paleontologists) have no ideas about these structures, and what they look like.

The original submission only had figures 1 and 2. And this request is totally fair! If you are going to discuss six alternative hypotheses for some mysterious anatomical structure, it’s just responsible reporting to illustrate those things. That goes double if, as Niels Bonde noted, the anatomy in question is unfamiliar to a lot of people, even many paleontologists. Huxley’s quote after first reading Darwin’s Origin of Species flashed through my head: “How extremely stupid not to have thought of that.”

Slide 21 of my 2014 SVPCA talk on supramedullary diverticula in birds and other dinosaurs, illustrating pneumatic foramina in the roof, walls, and floor of the neural canal.

At the time I read that review, I already had images illustrating five of the six hypotheses. A juvenile ostrich synsacrum that Jessie Atterholt and I had CT scanned gave us three of them all by itself: the lumbosacral expansion of the spinal cord to run the hindlimbs, as in all limbed tetrapods and in some fish with sensitive fins; the transverse channels in the dorsal wall of the neural canal to accommodate the lumbosacral balance organ; and the paired troughs in the floor of the neural canal that house the ventral eminences of the spinal cord (Figure 4D in the image at the top of this post). I had good photos of pneumatic foramina in the walls and floor of the neural canal in a dorsal vertebra of a rhea from my 2014 SVPCA talk (Figure 4B), and some photos of small foramina, presumably for blood vessels rather than air spaces, in the floor of the neural canal in a caudal vertebra of Apatosaurus (Figure 4A).

What I did not have is a photo illustrating the fairly abrupt, dome-shaped space in the sacral neural canal that houses the glycogen body of birds. I mean, I had published images, but I didn’t want to wrestle with trying to get image reproduction rights, or with redrawing the images. Instead, I went to the grocery store to buy some chicken.

I don’t know how universally true this is, but IME in the US when you buy a quartered chicken, the vertebrae are usually nicely hemisected by the band saw that separated the left and right halves of the animals. So you can see the neural canal in both the dorsal and sacral parts of the vertebral column. Here are the hemisected dorsal vertebrae in the breast quarter from a sectioned rotisserie chicken:

That’s just how it came to lie on my plate, but it’s not in anatomical position. Let’s flip it over to sit upright:

And label it:

I could and probably should do a whole post just unpacking this image, but I have other fish to fry today, so I’ll just note a couple of things in passing. The big interspinous ligament is the same one you can see in transverse section in the ostrich dissection photos in this post and this one. Also, the intervertebral joints heading toward the neck, on the left of the image, have much thicker intervertebral cartilage than the more posterior dorsals. That’s because the posterior ones were destined to fuse into a notarium. You can see a diagram and a photograph of a chicken notarium in figures 4 and 5, respectively, here. And finally, the big takeaway here is that the neural canal is normal, just a cylindrical tube to hold the spinal cord.

The thigh quarter usually has the pelvis and the hemisectioned synsacrum attached. Here’s a lateral view of the left half of the pelvis and synsacrum:

And the same thing labeled:

And now flipped around so we can see it in medial view:

And now that image labeled:

And, hey, there are three of our alternative hypotheses on display: the long (many vertebral segments) lumbosacral expansion of the spinal cord, which is reflected in a gradually expanded neural canal in the synsacrum; the shorter, higher dome-shaped recess for the glycogen body; and finally the transverse spaces for the lumbosacral balance organ.

As a refresher, there’s nothing terribly special about the lumbosacral expansion of the spinal cord — you have one, labeled as the ‘lumbar enlargement’ in the above diagram. Where the spinal cord has adjacent limbs to run, it has more neurons, so it gets fatter, so the neural canal gets fatter to accommodate it. The cord itself doesn’t look very expanded in the chicken photo above, but that chicken has been roasted rotisserie-style, and a lot of lipids probably cooked out of the cord during that process. What’s more important is that the neural canal is subtly but unmistakably expanded, over the span of many vertebrae.

The lumbosacral spinal cord of a 3-week-old chick in dorsal view. The big egg-shaped mass in the middle is the glycogen body. Watterson (1949: plate 1).

That’s in contrast to the recess for the glycogen body, which is colored in blue in the chicken photo. Glycogen bodies, like the egg-shaped one in the young chicken in the image immediately above, tend not to go on for many vertebral segments. Instead they balloon up and subside over the space of just 4 or 5 vertebrae, so they leave a different skeletal trace than other soft tissues.

Finally, there are the transverse spaces for the lumbosacral balance organ, which I discussed in this post. Those are the things that look like caterpillar legs sticking up from the sacral endocasts in the above figure from Necker (2006). In life, the spaces are occupied by loops of meningeal membranes, through which cerebrospinal fluid can slosh around, which in turn puts pressure on mechanoreceptive cells at the edge of the spinal cord and gives birds a balance organ in addition to the ones in their heads. In the photo of the cooked chicken, the delicate meninges have mostly fallen apart, leaving behind the empty spaces that they once occupied.

I really liked that chicken synsacrum, and I wanted to use it as part of Figure 4 of the new paper, but it needed a little cleaning, so I simmered it for a couple of hours on low heat (as one does). And it promptly fell apart. At least in the US, most of the chickens that make it to table are quite young and skeletally immature. That particular bird’s synsacrum wasn’t syn-anything, it was just a train of unfused vertebrae that fell apart at the earliest opportunity. I had anticipated that might be an issue, so I’d gotten a lot of chicken, including a whole rotisserie chicken and four thigh quarters from the deli counter at the local supermarket. Happily this fried chicken thigh quarter had a pretty good neural canal:

And it cleaned up nicely:

And with a little cropping, color-tuning, and labeling, it was ready for prime time:

I didn’t label them in the published version, for want of space and a desire not to muddy the waters any further, but the jet-black blobs I have colored in the lower part of that image are the exit holes that let the spinal nerves out of the neural canal so they could go serve the hindlimbs, pelvic viscera, and tail. We have them, too.

At my local grocery store, a fried chicken thigh costs about $1.65 if you get it standalone, or you can buy in bulk and save. You get to eat the chicken, and everything else I’ve done here required only water, heat, soap, and a little time. The point is that if I can do this, you can do this, and if you do, you’ll get to see some really cool anatomy. I almost added, “which most people haven’t seen”, but given how much chicken we eat as a society these days, probably most people’s eyes have fallen on the medial surface of a cooked chicken thigh quarter at one time or another. Better to say, “which most people haven’t noticed”. But now you can. Go have fun. 

Way back in January of 2019, I finished up “Things to Make and Do, Part 25b” with this line: “I have one more thing for you to look for in your bird vertebrae, and that will be the subject of the next installment in this series. Stay tuned!” Here we are, 2.3 years later, and I’ve finally made good. So if there’s a promised post you’ve been waiting for, stick around, we may get to it yet.

References

Last October, Mike posted a tutorial on how to choose a paper title, then followed it up by evaluating the titles of his own papers. He invited me to do the same for my papers. I waited a few days to allow myself to forget Mike’s comments on our joint papers – not too hard during my fall anatomy teaching – and then wrote down my thoughts.

And then did nothing with them for three and a half months.

The other day I rediscovered that draft and thought, hey, I don’t remember anything I wrote back then, I should redo the experiment and see if my evaluations will be consistent. And this time without looking at Mike’s post at all, so the risk of contamination would be even lower.

BUT FIRST I thought I should write down what I admire in paper titles, so I could see whether my titles actually lived up to my ideals. So now we can compare:

  • what I say I like in paper titles;
  • what I actually titled my papers;
  • what I had to say about my titles last October;
  • what I have to say about them now;
  • and, for some of my papers, what Mike had to say about them.

What I Admire In Paper Titles

Brevity. I first became consciously aware of the value of concise titles when I read Knut Schmidt-Nielsen’s autobiography, The Camel’s Nose, in 2004 or 2005. (Short-short review: most of the book is a narrative about scientific questions and it’s great, the self-congratulatory chapters near the end are much less interesting. Totally worth reading, especially since used copies can be had for next to nothing.) Schmidt-Nielsen said he always preferred short, simple titles. Short titles are usually punchy and hard to misunderstand. And I like titles that people can remember, and a short title is easier to recall than a long one.

Impact. In short, maximum information transfer using the minimum number of words. This is a separate point from sheer brevity; a paper can have a short title that doesn’t actually tell you very much. But brevity helps, because it’s difficult to compose a long title that really hits hard. Whatever impact a title might have, it will be diluted by every extraneous word.

Full sentences as titles. This is taking the information-transfer aspect of the last admirable quality to its logical extreme, although often at the expense of brevity. I was heavily influenced here by two things that happened while I was at Berkeley. First, I taught for a year in an NSF GK-12 program, where graduate students went out into local elementary, middle, and high schools and taught biology enrichment classes. One thing that was drilled into us during that experience is that we were teaching concepts, which ideally would be expressed as complete sentences. Also about that same time I read James Valentine’s book On the Origin of Phyla. The table of contents of that book is several pages long, because every chapter title, heading, and subheading is a complete sentence. This has a lovely effect: once you’ve read the table of contents of the book or any of its parts, you’ve gotten the TL;DR version of the argument. Sort of like a distributed abstract. I’d like to do that more.

How Did I Do?

Time to see if my actions match my words. Full bibliographic details and PDFs are available on my publications page. I stuck with Mike’s red-blue-green color scheme for the verdicts. My October 2014 and February 2015 thoughts are labeled. For joint papers with Mike, I’ve copied his assessment in as well. Any comments in brackets are my editorializing now, comparing what I said in October to what I said a few days ago before I’d looked back at my old comments or Mike’s.

* * * * * * * * * * * *

Sauroposeidon proteles, a new sauropod from the Early Cretaceous of Oklahoma. (11 words)

GOOD
Oct 2014: Like it. Short, to the point, includes the taxon name.
Feb 2015: Good, gets the job done with a minimum of fuss

Osteology, paleobiology, and relationships of the sauropod dinosaur Sauroposeidon. (9 words)

OK
Oct 2014: This title was inspired by the papers from the early 20th century
Feb 2015: It gets the job done, I suppose. I can’t help but wonder if there might have been a more elegant solution. Part of my unease is that this title is an example of the same attitude that produced the next monstrosity.

Osteological correlates of cervical musculature in Aves and Sauropoda (Dinosauria: Saurischia), with comments on the cervical ribs of Apatosaurus. (19 words)

BAD
Oct 2014: Ugh. It gets the job done, I suppose, but it’s waaaay long and just kind of ugly.
Feb 2015: Ugh. Waaay too wordy. I had a (fortunately brief) fascination with long titles, and especially the phrase, “with comments on”. Now I would cut it down to “Bony correlates of neck muscles in birds and sauropod dinosaurs” (10 words)

Vertebral pneumaticity, air sacs, and the physiology of sauropod dinosaurs. (10 words)

OK
Oct 2014: Like it. Would be better made into a sentence, like, “Vertebral pneumaticity is evidence for air sacs in sauropod dinosaurs.”
Feb 2015: Fairly clean. Does what it says on the tin. I’m having a hard time seeing how it could be turned into a sentence and still convey so much of what the paper is about in so few words.

[Heh. As we will see again later on, I was evidently smarter last fall than I am now.]

The evolution of vertebral pneumaticity in sauropod dinosaurs. (8 words)

GREAT

Oct 2014: Like it. It couldn’t really be any shorter without losing crucial information. Happy to have a decent title on my second-most-cited paper!
Feb 2015: Short, clean, probably my best title ever.

First occurrence of Brachiosaurus (Dinosauria: Sauropoda) from the Upper Jurassic Morrison Formation of Oklahoma. (14 words)

OK
Oct 2014: Yep. once you’ve read the title, you barely need to read the paper. Even better would have been, “A metacarpal of Brachiosaurus from the Upper Jurassic Morrison Formation of Oklahoma.” (12 words)
Feb 2015: Does what it says, but like my other PaleoBios pub, it’s a long title for a short paper. Now I would title it, “First record of the sauropod dinosaur Brachiosaurus from Oklahoma” (9 words)

[my October title was better!]

Postcranial skeletal pneumaticity in sauropods and its implications for mass estimates. (11 words)

OK
Oct 2014: It’s not elegant but it gets the job done. I wanted that paper to be one-stop shopping for sauropod PSP, but of course the real payoff there is the ASP/mass-estimate stuff, so I’m happy to have punched that up in the title.
Feb 2015: Good enough. I like it. It’s a little long–I could reasonably have just titled this, “Postcranial skeletal pneumaticity in sauropods”, but I wanted to draw attention to the implications for mass estimates.

Sauroposeidon: Oklahoma’s native giant (4 words)

OK
Feb 2015: Nice and short. Not terribly informative, but since this was a narrative about the discovery and description of Sauroposeidon aimed mostly at an Oklahoma audience, it’s not obvious how it could be improved.
[Note sure how missed this one last October, but I did.]

Origin of postcranial skeletal pneumaticity in dinosaurs. (7 words)

GOOD
Oct 2014: About all I would change now would be to add the word “early” at the beginning of the title.
Feb 2015: Great. Could not be shortened further without losing information.

What pneumaticity tells us about ‘prosauropods’, and vice versa. (9 words)

GOOD

Oct 2014: Love this title. I used it for the abstract of the SVP talk that the paper was derived from, too.
Feb 2015: Kind of a gimmick title, but it’s accurate–the SVP abstract this paper was based on was built around a bullet list. And it’s still nice and short.

Evidence for bird-like air sacs in saurischian dinosaurs. (9 words)

GOOD

Oct 2014: Along with Wedel (2003b) and Wedel (2006), this has a short (7-9 words apiece) title that tells you what’s in the paper, simply and directly. For once, I’m glad I didn’t turn it into a sentence. I think a declarative statement like “Saurischian dinosaurs had air sacs like those of birds” would have been less informative and come off as advertising. I wanted this paper to do what the title said: run down the evidence for air sacs in saurischians.
Feb 2015: I like it and wouldn’t change it. The “evidence for” part is key – I didn’t want to write a paper primarily about the air sacs themselves. Instead I wanted to lay out the evidence explaining why we think sauropods had air sacs.

Head and neck posture in sauropod dinosaurs inferred from extant animals. (8 words)

OK
Oct 2014: It’s not horrible but it would be better as a declarative statement like, “Sauropod dinosaurs held their necks and heads elevated like most other tetrapods.” (12 words)
Feb 2015: Good. Reads almost telegraphically brief as it is. Does what it says on the tin.

Mike: RUBBISH

[October Matt wins again!]

A new sauropod dinosaur from the Lower Cretaceous Cedar Mountain Formation, Utah, USA. (13 words)

OK
Oct 2014: Two things about this one. First, I wish we’d been able to include the taxon name in the title, as we were allowed to do back in the day for Sauroposeidon. Second, I know some people whinge about us using the CMF in the title and in the paper instead of the Burro Canyon Fm, which is what the CMF is technically called east of the Colorado River. But srsly, how many people search for Burro Canyon Fm versus CMF? All of the relevant faunal comparisons are to be made with the CMF, so I don’t feel the least bit bad about this.
Feb 2015: Fine. About as short as it could be and still be informative.

Mike: RUBBISH

The long necks of sauropods did not evolve primarily through sexual selection. Journal of Zoology. (12 words)

GOOD
Oct 2014: Perfect. The abstract and the paper expand on the title, but if all you read is the title, you know what we found. That’s a worthy goal.
Feb 2015: My first sentence title. Every word does work, so even though this is one of my longer titles, I like it. The length relative to my other titles is not a knock against this one; rather, it emphasizes how well I did at keeping my early titles short and to the point (with a couple of regrettable exceptions as noted above).

Mike: SWEET

The early evolution of postcranial skeletal pneumaticity in sauropodomorph dinosaurs. (10 words)

GOOD
Oct 2014: Not bad. I wonder if something like, “Widespread vertebral fossae show that pulmonary pneumaticity evolved early in sauropodomorphs” might be better. It’s hard, though, to put so many long, polysyllabic words in a title that doesn’t sound like a train wreck. At a minimum, this paper does what it says on the tin.
Feb 2015: Short and to the point. Another one that couldn’t be any shorter without losing valuable information.

A monument of inefficiency: the presumed course of the recurrent laryngeal nerve in sauropod dinosaurs. (15 words)

Objectively: BAD to OK
Subjectively: GOOD to FREAKIN’ AWESOME
Oct 2014: I readily admit that I could have fashioned a more informative title, but I dearly love this one. It’s derived from a TV commercial for cheeseburgers (true story), and it warms my heart every time I read it.
Feb 2015: This is definitely a gimmick title that is longer than it has to be (it would be a concise 11 words without the unnecessary intro clause) BUT I love it and I’d do it exactly the same if I could do it again. So there!

Why sauropods had long necks; and why giraffes have short necks. (11 words)

GOOD
Oct 2014: This is one of those ‘draw the reader in’ titles. I like it.
Feb 2015: We both liked the even shorter, “Why giraffes have short necks” but we really felt that a paper about sauropod necks needed sauropod necks in the title. I feel about this one like I feel about my 2007 prosauropod paper: it’s a gimmick title, but it’s short, so no harm done.

Mike: EXCELLENT

Neural spine bifurcation in sauropod dinosaurs of the Morrison Formation: ontogenetic and phylogenetic implications. (14 words)

OK
Oct 2014: Blah. It’s okay, not great. Maybe better as, “No evidence for increasing neural spine bifurcation through ontogeny in diplodocid sauropods of the Morrison Formation”, or something along those lines.
Feb 2015: This one is long but I think the length is necessary. It’s also kinda boring, but it was addressing a fairly dry point. I think any attempt to shorten it or sexy it up would come off as gratuitous.

Mike: WEAK

The effect of intervertebral cartilage on neutral posture and range of motion in the necks of sauropod dinosaurs. (18 words)

OK
Oct 2014: Probably better along the lines of, “Intervertebral spacing suggests a high neutral posture and broad range of motion in the necks of sauropod dinosaurs” or something like that.
Feb 2015: My second-longest title ever! Looking at it now, I think we could have titled it, “Effects of intervertebral cartilage on neck posture and range of motion in sauropod dinosaurs” and gotten it down to 14 words, but the word ‘neutral’ is doing real work in the original so maybe that’s a bust.

Mike: UGH, rubbish.

[October Matt is up by three points at least]

Caudal pneumaticity and pneumatic hiatuses in the sauropod dinosaurs Giraffatitan and Apatosaurus. (12 words)

OK
Oct 2014: Along the same lines as the previous: “Caudal pneumaticity and pneumatic hiatuses show that pulmonary diverticula in the tails of sauropod dinosaurs were pervasive and complex” or something.
Feb 2015: Good. Long only by comparison with some of my earlier titles. Does what it says.

Mike: NOT GOOD ENOUGH

The neck of Barosaurus was not only longer but also wider than those of Diplodocus and other diplodocines. (18 words)

GOOD
Feb 2015: My second sentence-as-title, and another entry in the run of mostly long titles from 2012 onward. I like how precise it is, despite the length.

Mike: GOOD

A ceratopsian dinosaur from the Lower Cretaceous of Western North America, and the biogeography of Neoceratopsia. (16 words)

GOOD
Feb 2015: I had no say in this one (by choice, I’m sure Andy et al. would have listened if I had had any suggestions about the title, but I didn’t). If I could rewrite it, I’d probably make it even longer by adding in the word ‘new’ between A and ceratopsian

Haplocanthosaurus (Saurischia: Sauropoda) from the lower Morrison Formation (Upper Jurassic) near Snowmass, Colorado. (13 words)

OK
Feb 2015: Feels a lot longer than its 13 words, mostly because so many of the words are polysyllabic. Normally I like pulling the words in parentheses out, but in this case I can’t see that doing that would actually improve the title. Sometimes descriptive papers need plain titles. It’s okay.

* * * * * * * * * * * *

Lessons

First, Mike graded harder than I did. In fact, I only rated one of my titles as BAD, which seems a bit feeble. I think we were using different criteria. If a title was boring but serviceable, I gave it an OK, whereas Mike tended to flag any suboptimal title as RUBBISH. But I didn’t remember that about his post, and I deliberately avoided looking at it until I’d made my evaluations.

Second, except for the two PaleoBios papers, all of the titles from the first half of my career (2000-2007) are 12 words or fewer, including a substantial bundle from before I’d read either The Camel’s Nose or Strunk & White. I’m sure that being a Cifelli student and then a Padian student had something to do with that; Rich and Kevin made me into the word choice and grammar pedant that I am today (my rhetorical excrescences on this site are my fault, not theirs).

Third, much to my surprise and consternation, my titles have gotten longer over time, not shorter. Partly that’s because my little corner of the science ecosystem is getting increasingly subdivided, so it’s hard for me to write a paper now with a title as broad as, “The evolution of vertebral pneumaticity in sauropod dinosaurs.” (Possibly a prod to keep seeking out new, more open horizons?) And I suppose there is some tension between brevity, informativeness, and precision. For example, saying in the title of a descriptive paper than a specimen is “from the Upper Jurassic Morrison Formation of [Location], [State or Country]” adds 11 words, but the title really does need those words. That could be a segue into a whole other discussion about descriptive versus analytical work, but that will be a topic for another time.

Ultimately, this has been a fun exercise and it’s made me more aware of how I title my papers. This is useful because I have some manuscripts in the works that deal with really detailed anatomy, and I need to figure out how to give them titles that are precise and informative but still punchy. It’s not easy.

Parting thought: after I posted the slides from my photography and illustration talk, Mike and I talked about posting some of our figures and dissecting them to see how they could be improved (it’s axiomatic that almost all figures could be improved in one way or another). We should really get started on that.

This came out two months ago, and I should have blogged about it then, but as usual I am behind. I’m blogging about it now because it deals with a question that has been on my mind for about 10 years now. If you want to skip my blatherations and get on to the good stuff, here’s the paper (Martin and Palmer 2014).

An Unsolved Problem

Back in 2004 I realized that if one had CTs or other cross-sections of a pneumatic bone, it was possible to quantify how much of the cross-sectional space was bone, and how much was air, a ratio I called the Air Space Proportion (ASP). That was the subject of my 2004 SVP talk, and a big part–arguably the most important part–of my chapter in The Sauropods in 2005. Of course the same calculation works for marrow-filled bones as well, where you would refer to it as an MSP rather than an ASP. If you can quantify the areas of bone, air, and marrow, you can figure out how dense the element was. One-stop shopping for all the relevant (simple) math is in this post.

(From Wedel 2005)

(From Wedel 2005)

Sometimes in science you end up with data that you don’t know what to do with, and that was my situation in 2004. Since I had CTs and other cross-sectional images of sauropod vertebrae, I could calculate ASPs for them, but I didn’t know what those results meant, because I didn’t have anything to compare them to. But I knew where to get I could get comparative data: from limb bone cross-sections. John Currey and R. McNeill Alexander had published a paper in 1985 titled, “The thickness of the walls of tubular bones”. I knew about that paper because I’d become something of an R. McNeill Alexander junkie after reading his book, Dynamics of Dinosaurs and Other Extinct Giants (Alexander 1989). And I knew that it had data on the cross-sectional properties of the limb bones in a host of animals, including crocs, birds, mammals, and–prophetically–pterosaurs.

If you know the inner and outer radii of a tubular bone, it is trivial to convert that to an ASP. So I could take the data from Currey and Alexander (1985) and calculate ASPs for the pneumatic bird and pterosaur bones in their study. Cubo and Casinos (2000) had a much larger sample of bird limb bones, and those got fed into my 2005 paper as well.

I was alert to the possibility that a mid-shaft cross-section might not be representative of the whole bone, and I hedged a bit in describing the bird ASPs (Wedel 2005: p. 212):

For the avian long bones described above, data were only presented for a single cross sec- tion located at midshaft. Therefore, the ASP values I am about to discuss may not be representative of the entire bones, but they probably approximate the volumes (total and air) of the diaphyses. For tubular bones, ASP may be determined by squaring K (if r is the inner diameter and R the outer, then K is r/R, ASP is πr^2/πR^2 or simply r^2/R^2, and ASP = K^2). For the K of pneumatic bones, Currey and Alexander (1985) report lower and upper bounds of 0.69 and 0.86, and I calculate a mean of 0.80 from the data presented in their table 1. Using a larger sample size, Cubo and Casinos (2000) found a slightly lower mean K of 0.77. The equivalent values of ASP are 0.48 and 0.74, with a mean of 0.64, or 0.59 for the mean of Cubo and Casinos (2000). This means that, on average, the diaphysis of a pneumatic avian long bone is 59%–64% air, by volume.

Now, even though I hedged and talked about diaphyses (shafts of long bones) rather than whole bones, I honestly expected that the ASP of any given slice would not change much along the length of a bone. Long bones tend to be tubular near the middle, with a thick bony cortex surrounding the marrow or air space, and honeycombed near the ends, with much thinner cortices and lots of bony septa or trabeculae (for marrow-filled bones, this is called spongy or trabecular bone, and for air-filled bones it is best referred to as camellate pneumatic bone). I figured that the decrease in cortical bone thickness near the ends of the bone would be offset by the increase in internal bony septa, and that the bone-to-air ratio through the whole element would be under some kind of holistic control that would keep it about even between the middle of the bone and the ends.

It is fair to ask why I didn’t just go check. The answer is that research is to some extent a zero-sum game, in that every project you take on means another that gets left waiting in the wings or abandoned completely. I was mainly interested in what ASP had to say about sauropods, not birds, and I had other fish to fry.

So that’s me from 2004-2012: aware that mid-shaft cross-sections of bird and pterosaur long bones might not be representative of whole elements, but not sufficiently motivated to go check. Then at SVPCA in Oxford that fall, Liz Martin rocked my world.

journal.pone.0097159.g001

Figure 1. CT scan images from two different regions of pterosaur first wing phalanx. A and B show the unmodified CT scans from A) the distal end of UP WP1 and B) the mid-shaft of UP WP1, while C and D show the modified and corrected images used in the calculation. Air space proportion (ASP) is calculated by determining the cross-sectional area of the internal, air filled cavity (the black centre of D) and dividing that by the total cross-sectional area, including the white cortical tissue and the black cavity. In areas with trabeculae, like C, the calculation of the air space includes the air found in individual trabeculae around the edges. Scale = 10 mm. doi:10.1371/journal.pone.0097159.g001 (From Martin and Palmer 2014)

A Paper in the Can

At SVPCA 2012, Liz Martin gave a talk titled, “A novel approach to estimating pterosaur bone mass using CT scans”, the result of her MS research with Colin Palmer at the University of Bristol. In that talk–the paper for which has been submitted to JVP–Liz and Colin were interested in using CT scans of pterosaur bones to quantify the volume of bone, in order to refine pterosaur mass estimates. I was fully on board, since estimating the masses of extinct animals is a minor obsession of mine. But what really caught my attention is that Liz and Colin had full stacks of slices spanning the length of each element–and therefore everything they needed to see how or if ASPs of pterosaur wing bones changed along their lengths.

At the next available break I dashed up to Liz, opened up my notebook, and started scribbling and gesticulating and in general carrying on like a crazy person. It’s a wonder she didn’t flee in terror. The substance of my raving was that (1) there was this outstanding problem in the nascent field of ASP research, and (2) she had everything she needed to address it, all that was required was a little math using the data she already had (I say this as if running the analyses and writing the paper were trivial tasks–they weren’t). Fortunately Liz and Colin were sufficiently interested to pursue it. Their paper on ASPs of pterosaur wing bones was submitted to PLOS ONE this February, and published on May 9 (while their earlier paper continues to grind its way through JVP).

And I’m blogging about it because the results were not what I expected.

Pterosaur wing bone ASPs - Martin and Palmer 2014

Figure 2. Plot of air space proportion over the length in six pterosaur wing bones. These plots show a polynomial line fit for each bone to show the general shape distribution. Exact measurements can be seen in Table S1. (From Martin and Palmer 2014).

Here’s the graph that tells the tale. Each line traces the ASP per slice along the length of a single pterosaur wing bone. A few things jump out:

  • Almost all of the lines drop near the left end. This is expected–if you’re cutting slices of a bone and measuring the not-bone space inside, then as you approach the end of the bone, you’re cutting through progressively more bone and less space. A few of the lines also drop near the right. I’m puzzled by that–if my explanation is correct, the ASP should plunge about equally at both ends. And the humerus USNM 11925 doesn’t follow the same pattern as the rest. As Martin and Palmer write, “It is unknown if this is a general feature of humeri, or this single taxon and more investigation is needed.”
  • Almost all of the bones have MUCH lower ASPs at mid-shaft than near the ends, on the order of 10% or more. So mid-shaft cross-sections of pterosaur wing bones tend to significantly underestimate how pneumatic they were. It would be interesting to know if the same holds true for bird long bones, or for the vertebrae of pterosaurs, birds, and sauropods. As Martin and Palmer point out, more work is needed.
  • The variation in ASP along the length of a single bone is in some cases greater than the variation between elements and individuals. That’s pretty cool. On the happy side, it means that getting into the nitty-gritty of ASP is not just stamp-collecting; you really need to know what is going on along the length of a bone before you can say anything intelligent about ASP or the density of the element. On the less happy side, that’s going to be a righteous pain in the butt for sauropod workers, because vertebrae are tough to get good scans of, assuming they will fit through a CT scanner at all (most don’t).
  • Finally, pterosaurs turn out to be even more pneumatic than you would think from looking at the already-freakishly-thin-walled shafts of their long bones. That’s pretty awesome, and it dovetails nicely with the emerging picture that pneumaticity in ornithodirans was more prevalent and more interesting than even I had suspected–it’s in prosauropods (Yates et al. 2012) and brachiosaur tails (Wedel and Taylor 2013) and rebbachisaur hips (Fanti et al. 2013) and saltasaur shoulders (Cerda et al. 2012) and, er, a couple of places that I can’t mention just yet. So life is good.

A few last odds and ends:

You can read more of this story at Liz Martin’s blog, scattered over several recent posts.

If you have CTs of bones and you want to follow in the footsteps of Martin and Palmer, you can do a lot of the work, and maybe all of it, in BoneJ, a free plug-in for ImageJ, which is also free.

A final note: this is Liz Martin’s first published paper, so congratulations are in order. Well done, Liz!

Almost Immediate Update: As soon as I posted this, I sent the link to Liz to see if I’d missed anything important. She writes, “It may be worth mentioning that it’s a question that I am actively following up on in my PhD, and looking into it with birds too hopefully. And it is indeed all possible using ImageJ, as that’s how I did the whole thing!”

References

How many open-access papers are getting published these days?  And who’s doing it?  Inspired by a tweet from @labroides (link at the end so as not to give away the punchline), I went looking for numbers.

We’ll start with our old friends Elsevier, since they are the world’s largest academic publisher by volume and by revenue.  One often reads statements such as “Elsevier is committed to Universal Access, Quality and Sustainability … Elsevier wants to enable the broadest possible access to quality research content in sustainable ways that meet our many constituents’ needs” (from their page Elsevier’s position on Access).  Even their submission to the OSTP call for comments begins by saying “One of Elsevier’s primary missions is to work towards providing universal access to high-quality scientific information in sustainable ways. We are committed to providing the broadest possible access to our publications.”

The most important way Elsevier does this is by allowing authors to pay a fee, currently $3000, to “sponsor” their articles, so that they are made freely available to readers (though we still don’t know under what specific licence!).  While that fee is more than twice the $1350 that PLoS ONE charges, it’s comparable to the $2900 PLoS Biology fee and identical to Springer’s $3000 fee.  Elsevier have rather a good policy in connection with their “sponsored article” fee: “Authors can only select this option after receiving notification that their article has been accepted for publication. This prevents a potential conflict of interest where a journal would have a financial incentive to accept an article.”

According to the page linked above, “691 Elsevier articles across some six hundred journals were sponsored in 2010. Sponsorship revenues from these articles amounted to less than 0.1% of Elsevier’s total revenues.”  (And indeed, 691 × $3000 = $2.073 M, which is about 0.065% of their 2010 revenue of £2026 M ≈ $3208 M.)  As Elsevier publishes 2639 journals in all, that amounts to just over a quarter of one open-access article per journal across the year.

I find that disappointing.

In the other corner (I won’t call it red or blue because of the political implications of those colours, which by the way are the opposite way around on different sides of the Atlantic.  Anyway …)  In the other corner, we have PLoS ONE.  According to its Advanced Search engine, this journal alone published 6750 open-access articles in 2010 — about ten times as many as all Elsevier journals combined.  Indeed, in the last month of that year alone, PLoS ONE’s 847 articles comfortably exceeded Elsevier’s output for the year.  That’s one journal, in one month, up against a stable of 2639 journals across a whole year.

What can we take away from this?  Maybe not very much: Elsevier offer their sponsored-article option to all authors, after all, and they can hardly be blamed if the authors don’t take them up on it.

But why don’t they?  Tune in next time for some thoughts on that.

And, finally, here is the tweet that started this line of thought:

@labroides Joshua Drew

@PublicAccessYAY @PLoSOne published more #OA articles in Dec ’10 than ALL of #elsevier‘s journals had the entire year

Food for thought.

There’s recently been a rash of requests for PDFs on the VRTPALEO mailing list.  Or maybe “plague” would be a better word.  What invariably happens is that a new paper comes out, and someone emails the list saying “Please can someone send me a PDF of this?”; then another half-dozen or so people all reply to the list saying “I’d like a copy, too”.  (The situation is exacerbated by the VRTPALEO list’s utterly advanced policy of forcing all replies to go to the whole list instead of just to the person being replied to, but that’s a whole nother rant.)

The result is of course that several thousand people get half a dozen spams.  Yes, it’s true that it only takes a couple of seconds to recognise and delete such messages.  But when two thousand people each take two seconds to delete a message, that’s 4000 seconds of time that could have been used for something useful.  In other words, to save yourself a couple of minutes’ work, you’ve wasted more than an hour of other people’s time.

Folks, this has to stop.

So what should you do when you want to get hold of a paper?  It’s a simple three-stage process.  And before you ask, yes, this is good for hobbyists as well as professionals.

Step 1: Google

Just search for the title of the paper.  You’d be surprised how often it just turns up.  Sometimes  it’s in an open-access journal, such as Acta Palaeontologica Polonica, Palaeontologia Electronica or PLoS ONE.  Sometimes the author has posted a copy, as for example I do with all my stuff and Matt does with his.  Sometimes, there just happens to be a copy lying around somewhere — for example, because a lecturer made it available to his students.

Often, though, the paper you want is out there, but paywalled.  So go on to …

Step 2: ask the author

Nine times out of ten, the abstract pages that the big commercial publishers put up include the author’s email address.  So just drop him or her a line asking for a copy.

Dear Dr. Haddockwhittler,

I was interested to see the abstract of your new paper on eroded non-diagnostic ornithopod pedal phalanges in the Journal Of Small Boring Fossils. I would be very grateful if you would send me a PDF. Many thanks.

And you’ll almost always get the PDF back within a day or two.  Sometimes authors don’t respond at all — most likely because they’ve not seen the message; and very occasionally they don’t have the PDF themselves.  But these are very rare situations.  And I have never, ever, known an author to just flatly refuse to send out a PDF.

I’ve had a few people telling me that they’re nervous about cold-contacting an Actual Credentialled Professional, and that they fear getting the brush-off because of their own amateur status.  Put this foolish idea out of your mind. Every professional is always delighted when anyone, professional or not, is interested in their work.

SPECIAL BONUS FRINGE BENEFIT: every now and then, you may find that as a by-product of such a request, you strike up a conversation with the author.  If you and they are interested in the same stuff, you sometimes find that you each have light to shed on the others’ thoughts.  As a matter of fact, this is precisely how I met and became friends with Matt (which in turn is how I became a palaeontologist — a story that I must tell some time in Tutorial 10: how to become a palaeontologist).  Usually this won’t happen: you’ll just have a brief, courteous exchange, and move on.  But sometimes it might.

But suppose you can’t find the author’s email address?  (This is much more common with older papers.)  Or suppose it’s a really old one — a classic Janensch paper or something — and the author is dead?  Or suppose you send an email, but the author never responds?  Then on to …

Step 3: ask a friend

If you know someone who’s at an institution that has good access to subscription resources, drop them a line as ask whether they’d mind pushing a copy your way.  If you’re friends already it’s probably because you’re interested in the same stuff, which means that they’ve likely already downloaded the paper in question — or, if not, they’ll be grateful to you for the heads-up.  Even if not, you’re only wasting one person’s time instead of two thousand.

And if all else fails …

… then fall back to the original: email the list and ask whether anyone can help.  Sure, there’s a place for this: it’s part of what the list is there for, and it can be absolutely invaluable when you’re trying but failing to track down an obscure old paper.

If you do this, then please use a meaningful subject for your email.  If you just write “PDF request” than I will delete it without even opening it, and I bet most other people will, too.  Do yourself a favour and write something terse but informative, like “Looking for PDF of Haddockwhittler 2010 on ornithopod phalanges”.

Another situation where mailing the list with a PDF request is appropriate: when you don’t know exactly what it is that you’re looking for, and you need expert guidance.  For example, I did this when looking for an ostrich osteology: I didn’t know of a good one (and hadn’t been able to discover the existence of one using Google), so I asked.  Not a problem.

But, people, this should be the last resort, not the first.

(There are those that say Inter-Library Loan should be on the List Of Things To Do Before Spamming VRTPALEO, but that’s not usually an option for amateurs with no formal affiliation.)

Well, I hope that’s helpful.  Now go forth and obtain papers!

This post is an expanded version of an email that I have written many, many times to individuals.  I got bored of writing it over and over, and figured that it would be quicker and easier to post this, and then be able to point people to it.

I have a much less realised view of the digital future than Matt does, so I won’t be making a lot of predictions here.  But I do have some questions to ask, and — predictably — some whining to do.

What counts, what doesn’t, and why?

Assuming you have made some science (e.g. a description of fossil, a palaeobiological hypothesis supported by evidence, a taxonomic revision), there are plenty of different ways you can present it to the world.  I may have missed some, but here are the ones I’ve thought of, in roughly descending order of respectability/citability/prestige:

  • Peer-reviewed paper/book chapter
  • Unreviewed paper/book chapter
  • Peer-reviewed electronic-only paper
  • Published abstract (e.g. for SVP)
  • Conference talk
  • Conference poster
  • Dissertation
  • Online supplementary information
  • Blog post
  • Blog comment
  • Email to the DML (which is archived on the web)
  • Personal email
  • Chat over a beer

How many of these are Science?  Where is the line?  Is the line hard or fuzzy?  Why is it OK to cite SVP abstracts but not so much SVPCA abstracts?  And other such questions. I think a very good case can be made that dissertations — provided they are made available — are better sources than conference talks, posters and abstracts; and a pretty good case can be made that blog posts are (especially when webcitation’ed — see below).  Both dissertations and (good) blog posts have the advantage over talks and posters that they have a permanent existence, and over abstracts the simple fact that they are substantial: a 200-word abtract cannot, by its very nature, say anything much.

Zoological nomenclature

Unfortunately, for nomenclatural purposes, the ICZN’s Article 8 currently says that only publications on paper count, period, which counts out dissertations.  I say unfortunately because were it not for this rule, then at least part of Aetogate would never have happened: the ramifications of Bill Parker’s case would not have been so awful if the perfectly good description of Heliocanthus in his (2003) dissertation had been allowed priority over Lucas et al.’s (2006) rush-job which attached the name Rioarribasuchus to the same specimen. Happily, the ICZN is as we write this considering an amendment to recognise nomenclatural acts in electronic-only publications.  There has already been some published discussion of the pros and cons of this amendment, and the Commission is actively soliciting further comments, so those of you with strong feelings should put them in writing and send them to the Executive Secretary.  (I will certainly be doing so.)

Self-scooping

We all know that blog entries are Not Sufficiently Published to be citable, at least in most journals; but are they Too Published to let you re-use the same material?  When you submit to most journals, they ask you to formally state “this material has not previously been published” — is that true if we’ve blogged it?  I am guessing different editors would answer that differently. For what it’s worth, we’ve been reasonably careful up till now not to blog anything that we’re planning to make into a paper — which is why we were so mysteriously silent on the obviously important topic of sauropod neck posture during the first 19 months of SV-POW!.  We’ve not been 100% pure on this: for example, I have a paper on Brachiosaurus in press that mentions in passing the spinoparapophyseal laminae, absence of an infradiapophyseal laminae and perforate anterior centroparapophyseal laminae of the 8th dorsal vertebra of the Brachiosaurus brancai specimen HMN SII — the features that I have blogged here in detail, with illustrations that would certainly never have been given journal-space.  Since the relevant passage in my paper accounted for half a manuscript page (of a total of 75 pages), I’m assuming no-one’s bothered about that.  In a case like this, I guess the SV-POW! posts are best thought of as pre-emptive and unofficial online supplementary information.

Counts for what purpose?

We’ve already mentioned that dissertations, blog entries and suchlike don’t count for nomenclatural purposes.  Whether they count in the sense of being citable in published works is up for debate right now (and again, see below on webcitation).  It seems pretty clear that these forms of “grey publication” do count in establishing people’s reputations among their peers — dissertations are obviously important in this regard, and Darren’s ridiculously broad knowledge of tetrapods extant and extinct is near-universally recognised largely because of his blogging efforts (although you could argue — and Matt and I often have argued — that he might have been able to enhance his reputation even more if he’d taken some of that blogging time and invested it in formal publications). Conversely, it’s clear that blogs, however rigorous and scientific, count for squat when it comes to committees.  The world of dinosaur palaeontology is probably just as aware of Matt’s series of Aerosteon response articles here on SV-POW! as it would be if he’d put those together into a paper that was published in PLoS ONE; but when his tenure committee comes to count up the impact factors of the journals he’s published in, those articles will count for nothing.  One day that might change, but not while impact factors still exert their baleful influence.

Deciding what to blog and what to write up as a “proper paper”

Matt posted his response to the Aerosteon paper as a sequence of three blog entries even though he knew that what he had to say was substantial enough to make a paper.  Why throw away a potential publication that would look good on the CV?  Because he wanted to get it out there ASAP, and didn’t want to wait until all the media dust had settled.  So he fought people off when they pestered him to publish it as a paper.  He doesn’t really need to do it now, and he doesn’t really have time (especially since I keep badgering him about all the papers we’re supposed to be collaborating on).  If we were starving for publications, we could turn a lot of SV-POW! posts into LPUs — but we’re not starving.

Let me explain this by taking a digression though the economics of file-sharing and the way labels persistently — maybe deliberately — misunderstand them.  Let’s imagine for the sake of an example that a while back, I sent Matt the MP3s that make up Blue Oyster Cult’s awesome Fire Of Unknown Origin album.  Now anyone with their brain switched on can see that the net effect of this on his music-buying pattern would be positive: if he really liked Fire, there is a fair chance that he would then have gone and bought a BOC album or two, or three — just as I’ve been buying Dar Williams albums like crazy since someone slipped me MP3s of Mortal City.  The labels’ perception, however, is that instead I would have denied them a sale: that if I’d not sent the Fire of Unknown Origin MP3s, Matt would of course have bought his own legitimate copy, and so I’ve stiffed them out of $6.99 less whatever tiny slice they pass on to the artist.  The misunderstanding here is that they think — or would like to think, who knows if they really believe this themselves? — that people’s music consumption is limited by the time we have available to listen to music, and that one way or another we will obtain enough music to fulfil that need: for free if possible, but by paying for it if necessary.  But the truth is completely different: there would be zero chance of Matt’s ever buying any BOC album, since he’d never even heard of them (beyond Don’t Fear The Reaper, I guess) whereas in the hypothetical universe where I sent him the Fire MP3s, there is a non-zero chance.  And the labels’ failure to understand that is because of a wholly incorrect model of what factor limits music listening.

Digression ends.  Its relevance is this: in the same way, we are used to thinking that our ability to get papers published is limited by the number of publication-worthy ideas we have — so that every paper idea we “waste” on a blog entry is a net loss.  In truth, ideas are cheap, and our ability to get papers published is actually limited by our throughput — our ability to find time to actually write those ideas up with sufficient rigour, prepare high-resolution figures, format the manuscripts for journals, wait through the review period, deal with the reviews, revise, resubmit, handle editorial requests, and so on and on.  (That is especially true when the journal takes six months to come up with a rejection.) This is why Matt and I, like everyone else I know in palaeo who I’ve discussed this with, have huge stacks of POOP that we’ve not yet found time to convert into papers.  So when we spend a paper-worthy idea on a blog entry, we’re not wasting it: we’re putting it out there (in an admittedly inferior format) when otherwise it would never have made it out there at all. The remaining issue is whether the time we spend on blogging an idea would have been better spent on moving a paper further towards publication.  Maybe, sometimes.  But you have to stop and smell the roses every now and again.  So the real cost of SV-POW! for us is not the “waste” of paperable ideas, but the time we spend on writing it.  I am guessing that in the time I’ve put into SV-POW! so far, I could have got two more papers out — certainly one.  Has it been worth it?  I think so, but it’s not a no-brainer.  On the other hand, SV-POW! probably acts as a reader-funnel, so that when I do get a paper out, more people read it than otherwise would.  How big that effect is, I don’t know, and I can’t think of a way to measure it.

How to cite blog entries: WebCite

One of the great things about writing for SV-POW! is that you can learn some really useful stuff from the comments; and the most useful comment I’ve seen so far is the one in which Cameron Neylon pointed us at WebCite (http://webcitation.org/).  This is a superbly straightforward site that makes permanent archive copies of web-pages, and mirrors them around the world.  In doing so, it deals with the problems of web pages being vulnerable to disappearance and prone to change.  (In off-list emails with Matt, I had suggested that I might build something like this myself, as I am software engineer in my day job; I am delighted that these guys have done it properly instead.) So if you ever want to cite Matt’s second Aerosteon post in a journal, use the archive URL http://webcitation.org/5hPYTmWpW — and if you want to cite any other SV-POW! article, just submit its URL to WebCite yourself, and get back an archive URL which you can use. And tell all your friends about WebCite!

Oh, and by the way …

Here’s that photo of a monitor lizard getting its arse kicked by an elephant that you ordered:

Monitor lizard postcranium, aerial. Photograph by Hira Punjabi, downloaded from National Geographic.

Monitor lizard postcranium, aerial, strongly inclined. Photograph by Hira Punjabi, downloaded from National Geographic

References

  • Lucas, S. G., Hunt, A. P. and Spielmann, J. A. 2006. Rioarribasuchus, a new name for an aetosaur from the Upper Triassic of north-central New Mexico. New Mexico Museum of Natural History and Science, Bulletin 37: 581-582.
  • Parker, W. G. 2003a. Description of a new specimen of Desmatosuchus haplocerus from the Late Triassic of Northern Arizona. Unpublished MS thesis. Northern Arizona University, Flagstaff. 315 pp.

First off, thanks to everyone for reading, commenting on, and discussing the previous post. Seeing the diversity of opinions expressed has been interesting and gratifying for us, and we’ve learned a lot from you about how the blogosphere is changing science already. My own thoughts follow, Mike chimes in at the end, and Darren will probably have something to add soon, too.

The Intolerable Problem

Sometimes people push back on posts of mine they don’t like by telling me I’m out of bounds. Somehow, they say, I’ve crossed the boundary of what I’m allowed to write about. They are angry that I’m now writing about something outside my defined area.

I’m usually taken aback by this, because I didn’t realize I’d actually agreed to any boundaries.

Seth Godin, 2009, “Out of Bounds”

Several commenters have brought up what I call the Intolerable Problem, which is that people online can critique papers and present new evidence and arguments in a format that is impermanent and not peer-reviewed. It’s intolerable because on one hand such material is not currently (operative word) citable in most outlets, and on the other hand repeating it sans citation in peer-reviewed literature smacks of plagiarism (to some, but not to all). Although this material is potentially valuable it “doesn’t count” professionally (see exceptions below), which some professionals (not necessarily those who have commented here) regard as a fatal argument against posting it in the first place. But–and this is crucial–it’s only a problem for the tiny fraction of the audience who might want to cite the freely exchanged material. If you’re in that fraction, we value your attention and comments, but don’t assume we’re writing only for you, or to further our professional standing. We blog because we love this stuff, and even at a technical niche blog like SV-POW! the majority of readers probably don’t care at all whether the information is peer-reviewed or “counts” for professionals; they mostly care whether it’s right or not.

One obvious solution to the Intolerable Problem is to simply let people cite anything they want, including blog posts and DML posts. This is already starting to be implemented–see examples here and here and more discussion here. This runs into two problems: one is permanence (there is no guarantee that the cited post will be up forever, or that the author won’t revise it later in response to criticism [as I have done with this very post!]), which can already be solved using tools such as WebCite (thanks to Cameron Neylon for bringing this to our attention in a comment on the previous post).

The other problem is that citations serve two functions, which are to establish priority and to lend authority to an argument. Citing a blog post may establish priority, but some researchers will cavil at the idea that a blog post is an authoritative source (for varying combinations of researchers and blog posts). Whether they would be right to cavil I don’t know; in the end the market will decide. The market–that is, the desire to attain professional respect and avoid censure–will also dissuade authors from larding up their papers with citations to trivial or worthless online sources.

Those who are troubled by the free discussion of papers, evidence, and hypotheses online need to realize that:

  • it’s been going on for a long time (15 years for the Dinosaur Mailing List);
  • it’s only going to accelerate in the future;
  • it’s not a problem for the vast majority of people participating in the discussions;
  • any solution must involve accommodation to the reality of how people exchange information online (immediately, freely, globally, without prior filtering).

These discussions are not going to stop, and ignoring the output of such discussions (because they “don’t count”) will eventually become prohibitively expensive as those workers who insist on playing only by the old rules are outmaneuvered by others who find ways to use all available information regardless of its provenience or “respectability”.

Paper journals will die when online journals stop sucking

Most online publications are hampered by having to be identical to the dead-tree versions (no links, no embedded video, no rotating 3D PDF images, etc.). Eventually people will realize that it is counterproductive to keep hobbling the new medium to make it as slow, flat, and inefficient as the old medium. Once one journal takes the hobbles off, others will do the same rather than lose contributors to cutting-edge outlets. A few boutique journals may still produce flattened, gutted versions of the online publications on paper. People still fly biplanes, too. Paper-based journals will never be popular again and their existence will not stop people from doing whatever technology allows them to in the online venues.

Note that this does not even refer to the economic argument against dead-tree publishing, which has already relocated encyclopedias and newspapers from ubiquity to marginality or extinction.

I’m surprised that the revolution isn’t farther along already. The cage is open.

Whither peer review and editing?

This is all part of the Big Flip in publishing generally, where the old notion of “filter, then publish” is giving way to “publish, then filter.” There is no need for Slashdot’s or Kuro5hin’s owners to sort the good posts from the bad in advance, no need for Blogdex or Daypop to pressure people not to post drivel, because lightweight filters applied after the fact work better at large scale than paying editors to enforce minimum quality in advance.

Clay Shirky, 2003, “The Music Business and the Big Flip”

PLoS ONE is already going gangbusters, without peer-review prior to publication in many cases. The only holdup there is that the post-hoc review by commenters is not working out quite like they’d hoped, because few people are commenting. Not everyone agrees that there is a dearth of commenting at PLoS ONE; the larger point is that people publish there a lot and the community treats those pubs like they count, even though in many cases they are essentially un-reviewed.

[Update: I misunderstood peer review at PLoS ONE. Papers may be reviewed externally by people unconnected to PLoS, or by one or more unpaid Academic Editors, or by a combination. I had thought of the review by Academic Editors only, which accounts for 13% of papers, as a form of internal review, but according to Bora (down in the comments) it should count as external review. If you’re happy with that–and the system is not without its critics–then all papers at PLoS ONE are externally reviewed prior to publication; even if you’re not, pre-publication review by someone is still in place across the board at PLoS ONE, and 87% of papers are externally reviewed by people unaffiliated with PLoS. Post-publication commenting supplements rather than replaces pre-publication review.]

People do comment on blogs, all the time. Post-hoc review will work, in fact already does work, just fine on blogs. I predict that PLoS ONE clones of the future (PLoS TWO?) will emulate whatever features of blogs make people willing to comment on them but not on PLoS ONE v1.0.

Alternatively, the paucity of post-hoc commenting at PLoS ONE could be taken as further evidence that journal-mediated peer review, whether before or after publication, is dying just off to a slow start. I think that editorial control is not far behind. Both are locally extinct in some parts of the science publishing ecosystem, since people are already citing blogs.

Q: But–but–but? What about protecting the sanctity of the process? What about about guaranteeing respectability? What about prestige?

A: Hey, those questions would make a terrific opinion piece for your local newspaper–oops, too late.

I don’t deny that editors and peer reviewers often make significant contributions to the quality of published work. I just think that people will learn to get along without them if doing so allows faster and easier exchange of information. That was never possible on paper; it’s long been possible here.

A priori peer review and editorial control were invented because publications were scarce (in the Econ 101 sense of being limited) and there needed to be a barrier to entry. Now publication is instant, free, and global. Error correction and the assignment of value will still happen, but they’ll happen after publication rather than before, and they’ll be distributed rather than centralized.

Creeping blogification

Clay Shirky described the problem for newspapers and the recording industry as the existence of “cheap perfect copies”. An expanded but by no means exhaustive list for science publication includes:

  • cheap perfect copies
  • editable (but also archivable)
  • sharable
  • linkable (both incoming and outgoing)
  • globally distributed
  • instantly
  • for free
  • without pre-publication filtering
  • with multimedia embeds (as opposed to including video etc. separately in the suppl. info.)

Online open-access journals currently take advantage of all of those capabilities except the last two. Newsgroup posts cover all the bases except the last one (so do tweets, despite the severe length limitations).

What covers everything? Blog posts. Which have the added advantage that people will comment on them without being asked.

But that’s not the whole simple story.

The center cannot hold–or can it?

So we’re looking at total chaos, right–a world where anyone posts anything they want, no one has any control, and no one knows how to find the good stuff? Well, two out of three, at least. I’m not worried about that last point, for two reasons.

First, thanks to search engines, aggregators, tags, tweets, links, etc., we already have pretty good tools for finding the good stuff. Those direction finders will get better even as the map gets more complicated.

Second, prestige will always be a motivator, so people will always compete to get into exclusive venues. Nature is not going away, although I think that in the near future they will decouple their online and print publications so that the former can take advantage of all the possibilities the web offers.

If I have a really good idea backed up with lots of data, I’ll keep trying to get it into the most prestigious outlet I can. I won’t put my best stuff on a blog just because it’s faster and less encumbered. Blogs probably won’t replace journals, at least not anytime soon. Rather, the spectrum of publishing possibilities will expand; below the category of Least Publishable Unit we’ll add Most Bloggable Unit and so on down to Least Tweetable Unit, and the new categories will interpenetrate with the old over time.

How nice for me

Well, what a striking coincidence that Mr. Paleo Blogger looks into the ole digital crystal ball and sees “bloggy with a 90% chance of exactly-what-he’s-already-doing”.

I can’t claim to be either uninterested or unbiased in all of this. But I am new to actually thinking about the implications. I hadn’t been to most of the above links or had any of these thoughts as of a week ago. When Casey first e-mailed me six days ago, I replied:

If you’re curious, here’s the short short version of my thoughts: science bloggers critique published papers and blog about unpublished observations all the time. Our post-paper run of posts might be an extreme or even vulgar example, and it might fire more discussion about “what counts?”, but I don’t see it as being different in kind from what many science bloggers do. Papers are papers and blogs are blogs, and I never intended to blur the lines. If people feel that all the blog posts only count as “crap some guys wrote on the internet” and that they can be safely ignored, that’s fine with me. If they think the blog posts deserve some higher level of recognition a la “what counts?”, then I’m honored, but that’s extra value that others are investing in our blog, and not anything that we’ve knowingly sought. I suppose you could turn around and say that I’m trying to have my cake and eat it, too, first with all the pro-paper blogging and now with this “I’m innocent” schtick. I don’t know what the answer is, but I know that I’m too tired to figure it out tonight. All the more reason to have an open conversation about this stuff.

Now I realize that the lines between papers and blog posts are blurring, and whether we mean to or not, we SV-POW!sketeers are contributing (Darren’s doing double duty thanks to Tet Zoo). I still think that the investment of blog posts with respectability, value, citability, or whatever rests entirely with readers, and always will. Options range from treating posts like papers to treating them like bar conversations to treating them like spam. You decide.

Also, I tried to keep the writing above value-neutral but probably failed. It’s hard not to get a bit evangelistic about the potential advantages of online publication and online everything else, a tendency I call DISSUADE: Da Internet Shall Save Us All Dead-trees Excepted. Getting published in science hasn’t always been easy up until now, but the process has been relatively clear and familiar. And stable, on decadal and even centennial timescales. Everything about scientific publication is about to get much more fluid and much less clear, and it will probably stay that way for a long time, and it may stay that way forever. Not all of the changes will be for the better, and it may be hard to decide what’s better and what’s worse until we look back with some perspective. Mechanical looms were bad for weavers but good for everyone else. I think many of the changes discussed in this post and the previous comment thread are likely, and some are inevitable.

Set against the shiny digital future is the inertia of the academy and those of us who roost there. I’m not going to stop publishing papers in dead-tree journals (although I will never publish in a journal that doesn’t provide PDFs to authors). Heck, I’m not even going to stop publishing in closed-access journals, some of which are run by societies I admire and want to participate in (after all, everything is open anyway). At the same time I will keep blogging, and while I will frequently bring up technical stuff I don’t want to publish more formally (at least not yet), I will try not to deliberately blur the lines any more than I already have. I don’t need to; the web is already blurring them faster than most of us can keep up.

Hang on.

Oh, about that mystery vert…

Metapophyses, I haz them

Metapophyses, I haz them

…at the end of the post Necks Lie. Nima called it–good spot on the split neural spine. It’s a mid-cervical of Barosaurus, AMNH 6341, in the big bone room (well, one of many big bone rooms) at the American Museum of  Natural History in New York. A cast of this vertebra makes up part of the neck in the awesome mounted skeleton in the museum rotunda. Here’s that skeleton, with Mike for scale.

Mike with Baro 480

Thanks for slogging through all this. We’ll get back to perforated postcentrodiapophyseal laminae, sacralized caudal transverse processes, and the air space proportions of pneumatic vertebrae soon.

Addendum

Matt is much more ready than I am to throw away peer-review, editorial control, and journals in general.  Sometimes, the reasons that things are the way they are, are good ones; it’s not in the interests of professional iconoclasts like Clay Shirky and Cory Doctorow to point that out or to discuss the strengths of how things are today, but that doesn’t mean we have to accept their arguments as uncritically as (say, to pick a name out of the air completely at random) Matt.

Anyway, happily, G. K. Chesterton foresaw the abolition of journals in favour of blogs, and commented thus:

Suppose that a great commotion arises in the street about something, let us say a lamp-post, which many influential persons desire to pull down. A grey-clad monk, who is the spirit of the Middle Ages, is approached upon the matter, and begins to say, in the arid manner of the Schoolmen, “Let us first of all consider, my brethren, the value of Light. If Light be in itself good–” At this point he is somewhat excusably knocked down. All the people make a rush for the lamp-post, the lamp-post is down in ten minutes, and they go about congratulating each other on their unmediaeval practicality. But as things go on they do not work out so easily. Some people have pulled the lamp-post down because they wanted the electric light; some because they wanted old iron; some because they wanted darkness, because their deeds were evil. Some thought it not enough of a lamp-post, some too much; some acted because they wanted to smash municipal machinery; some because they wanted to smash something. And there is war in the night, no man knowing whom he strikes. So, gradually and inevitably, to-day, to-morrow, or the next day, there comes back the conviction that the monk was right after all, and that all depends on what is the philosophy of Light. Only what we might have discussed under the gas-lamp, we now must discuss in the dark.

Heretics (1905).


The land of the free papers

February 20, 2009

UPDATE: Oops, I’m a moron. I wrote this post at work (on my lunch hour!) and didn’t realize that I had free access to the Wiley stuff because I was at work. I can’t get them from home either. But as a public service to disappointed readers, I will send PDFs of the three Wiley articles to anyone who e-mails me: mathew.wedel@gmail.com (spam bots can suck on Google’s filters, which are teh awesome).

Apologies to Jerry for the title (you DMLers know what I’m talking about). In case no one has drawn your attention to it, the rate of arrival of hot new SV-POW!-revelant papers has gone near-exponential lately. Here’s a short hit list, all a few of which are currently free downloads!

First, three hotties from the all-open-access, all-the-time PLoS ONE:

As long as you’re over at PLoS ONE, you might as well read up on fighting ceratopsians and pregnant land whales (be careful how you use that last phrase, too–we don’t want to lose any readers to domestic violence).

Next, two important recent papers from the Journal of Experimental Zoology (other than my own). These are free right now but who knows for how long, so download them pronto before they go behind a paywall to anyone who e-mails me for them.

Continuing with another sauropod paper from Germany, this time in the journal of the Museum fur Naturkunde in Berlin. This one is also currently free but may not be forever. Don’t tarry. You know the drill.

Finally, the redescription of Euhelopus by Jeff Wilson and Paul Upchurch is in press, and hopefully we will have a URL to add here soon (and hopefull it will also be free, at least for a while).

At least some segments of the music industry are getting used to the idea that file-sharing can be piracy, but it can also be free distribution and publicity. The new trend of corporate journals offering free downloads on current articles makes me wonder if they’re starting to think the same way [or not]. I’m reminded of John Gilmore’s famous line, “The net interprets censorship as damage and routes around it.” [like me] Authors are going to keep e-mailing PDFs to all of their friends and colleagues anyway; why not go with the flow? If everyone else’s stuff is being traded and read (and cited!) while yours is sitting behind a paywall, you lose; the “you” applies to both authors and publishers [unless some idiot volunteers to send your stuff around, in which case you only lose if you are the publisher]. End of rant.

Enjoy the new goods!

Here’s the mandated sauropod vert picture, which I believe has not appeared on this site before. I stole it from Darren as a gift to Mike–the poor widdle fing.

xeno-a-la-lydekker

This paper is a rather belated follow-up to Foster and Wedel (2014), “Haplocanthosaurus (Saurischia: Sauropoda) from the lower Morrison Formation (Upper Jurassic) near Snowmass, Colorado”. For more about that paper, see this page.

Citation and link to the paper

Wedel, Mathew; Atterholt, Jessie; Dooley, Jr., Alton C.; Farooq, Saad; Macalino, Jeff; Nalley, Thierra K.; Wisser, Gary; and Yasmer, John. 2021. Expanded neural canals in the caudal vertebrae of a specimen of Haplocanthosaurus. Academia Letters, Article 911, 10pp. DOI: 10.20935/AL911 (link)

SV-POW! posts

Pre-publication posts on the Snowmass Haplocanthosaurus project

  • Many, many posts, which I am not going to list at the moment, but I am leaving this here as a reminder to attempt it in the future.

Post-publications posts

High-resolution figures

A. Recovered skeletal elements of Haplocanthosaurus specimen MWC 8028. B. Caudal vertebra 3 in right lateral view. C. The same vertebra in posterior view. Lines show the location of sections for D and E. D. Midsagittal CT slice. The arrow indicates the ventral expansion of the neural canal into the centrum. E. Horizontal CT slice at the level of the neural arch pedicles, with anterior toward the top. Arrows indicate the lateral expansions of the neural canal into the pedicles. B-E are shown at the same scale. Wedel et al. (2021: fig. 1).

A. Photograph of a 3D-printed model of the first three caudal vertebrae of Haplocanthosaurus specimen MWC 8028, including endocasts of the neural canal (yellow) and intervertebral joints (blue), in right lateral view, and with the neural canal horizontal. B. Diagram of the same vertebrae in midsagittal section, emphasizing the volumes of the neural canal (yellow) and intervertebral joint spaces (blue). Anterior is to the right. Wedel et al. (2021: fig. 2).

Caudal vertebra 3 of Haplocanthosaurus specimen MWC 8028 in left posterolateral (A), posterior (B), and right posterolateral (C) views, with close-ups (D and E). In A and B, a paintbrush is inserted into one of the lateral recesses, showing that the neural canal is wider internally than at either end. Wedel et al. (2021: fig. 3).

Anatomical features of the neural canal in birds and other dinosaurs. A. MWC 9698, a mid caudal vertebra of Apatosaurus in posterodorsal view. Arrows highlight probable vascular foramina in the ventral floor of the neural canal. B. LACM 97479, a dorsal vertebra of Rhea americana in left anterolateral view. Arrows highlight pneumatic foramina inside the neural canal. C. A hemisected partial synsacrum of a chicken, Gallus domesticus, obtained from a grocery store. Anterior is to the right. The bracket shows the extent of the dorsal recess for the glycogen body, which only spans four vertebrae. Arrows highlight the transverse grooves in the roof of the neural canal for the lumbosacral organ. D. Sagittal (left) and transverse (right) CT slices through the sacrum of a juvenile ostrich, Struthio camelus. The bracket shows the extent of the lumbosacral expansion of the spinal cord. Indentations in the roof of the neural canal house the lumbosacral organ. In contrast to the chicken, the ostrich has a small glycogen body that does not leave a distinct osteological trace. Yellow arrows show the longitudinal troughs in the ventral floor of the neural canal that house the ventral eminences of the spinal cord. Wedel et al. (2021: fig. 4).

 

FIGURE 7.1. Pneumatic features in dorsal vertebrae of Barapasaurus (A–D), Camarasaurus (E–G), Diplodocus (H–J), and Saltasaurus (K–N). Anterior is to the left; different elements are not to scale. A, A posterior dorsal vertebra of Barapasaurus. The opening of the neural cavity is under the transverse process. B, A midsagittal section through a middorsal vertebra of Barapasaurus showing the neural cavity above the neural canal. C, A transverse section through the posterior dorsal shown in A (position 1). In this vertebra, the neural cavities on either side are separated by a narrow median septum and do not communicate with the neural canal. The centrum bears large, shallow fossae. D, A transverse section through the middorsal shown in B. The neural cavity opens to either side beneath the transverse processes. No bony structures separate the neural cavity from the neural canal. The fossae on the centrum are smaller and deeper than in the previous example. (A–D redrawn from Jain et al. 1979:pl. 101, 102.) E, An anterior dorsal vertebra of Camarasaurus. F, A transverse section through the centrum (E, position 1) showing the large camerae that occupy most of the volume of the centrum. G, a horizontal section (E, position 2). (E–G redrawn from Ostrom and McIntosh 1966:pl. 24.) H, A posterior dorsal vertebra of Diplodocus. (Modified from Gilmore 1932:fig. 2.) I, Transverse sections through the neural spines of other Diplodocus dorsals (similar to H, position 1). The neural spine has no body or central corpus of bone for most of its length. Instead it is composed of intersecting bony laminae. This form of construction is typical for the presacral neural spines of most sauropods outside the clade Somphospondyli. (Modified from Osborn 1899:fig. 4.) J, A horizontal section through a generalized Diplodocus dorsal (similar to H, position 2). This diagram is based on several broken elements and is not intended to represent a specific specimen. The large camerae in the midcentrum connect to several smaller chambers at either end. K, A transverse section through the top of the neural spine of an anterior dorsal vertebra of Saltasaurus (L, position 1). Compare the internal pneumatic chambers in the neural spine of Saltasaurus with the external fossae in the neural spine of Diplodocus shown in J. L, An anterior dorsal vertebra of Saltasaurus. M, A transverse section through the centrum (L, position 2). N, A horizontal section (L, position 3). In most members of the clade Somphospondyli the neural spines and centra are filled with small camellae. (K–N modified from Powell 1992:fig. 16.) [Figure from Wedel 2005.]

Here’s figure 1 from my 2005 book chapter. I tried to cram as much pneumatic sauropod vertebra morphology into one figure as I could. All of the diagrams are traced from pre-existing published images except the horizontal section of the Diplodocus dorsal in J, which is a sort of generalized cross-section that I based on broken centra of camerate vertebrae from several taxa (like the ones shown in this post). One thing that strikes me about this figure, and about most of the CT and other cross-sections that I’ve published or used over the years (example), is that they’re more or less bilaterally symmetrical. 

We’ve talked about asymmetrical vertebrae before, actually going back to the very first post in Xenoposeidon week, when this blog was only a month and a half old. But not as much as I thought. Given how much space asymmetry takes up in my brain, it’s actually weird how little we’ve discussed it.

The fourth sacral centrum of Haplocanthosaurus CM 879, in left and right lateral view (on the left and right, respectively). Note the distinct fossa under the sacral rib attachment on the right, which is absent on the left.

Also, virtually all of our previous coverage of asymmetry has focused on external pneumatic features, like the asymmetric fossae in this sacral of Haplocanthosaurus (featured here), in the tails of Giraffatitan and Apatosaurus (from Wedel and Taylor 2013b), and in the ever-popular holotype of Xenoposeidon. This is true not just on the blog but also in our most recent paper (Taylor and Wedel 2021), which grew out of this post.

Given that cross-sectional asymmetry has barely gotten a look in before now, here are three specimens that show it, presented in ascending levels of weirdness.

First up, a dorsal centrum of Haplocanthosaurus, CM 572. This tracing appeared in Text-fig 8 in my solo prosauropod paper (Wedel 2007), and the CT scout it was traced from is in Fig 6 in my saurischian air-sac paper (Wedel 2009). The section shown here is about 13cm tall dorsoventrally. The pneumatic fossa on the left is comparatively small, shallow, and lacks very distinct overhanging lips of bone. The fossa on the right is about twice as big, it has a more distinct bar of bone forming a ventral lip, and it is separated from the neural canal by a much thinner plate of bone. The fossa on the left is more similar to the condition in dorsal vertebrae of Barapasaurus or juvenile Apatosaurus, where as the one on the right shows a somewhat more extensive and derived degree of pneumatization. The median septum isn’t quite on the midline of the centrum, but it’s pretty stout, which seems to be a consistent feature in presacral vertebrae of Haplocanthosaurus.

 

Getting weirder. Here’s a section through the mid-centrum of C6 of CM 555, which is probably Brontosaurus parvus. That specific vert has gotten a lot of SV-POW! love over the years: it appears in several posts (like this one, this one, and this one), and in Fig 19 in our neural spine bifurcation paper (Wedel and Taylor 2013a). The section shown here is about 10cm tall, dorsoventrally. In cross-section, it has the classic I-beam configuration for camerate sauropod vertebrae, only the median septum is doing something odd — rather than attaching the midline of the bony floor of the centrum, it’s angled over to the side, to attach to what would normally be the ventral lip of the camera. I suspect that it got this way because the diverticulum on the right either got to the vertebra a little ahead of the one on the left, or just pneumatized the bone faster, because the median septum isn’t just bent, even the vertical bit is displaced to the left of the midline. I also suspect that this condition was able to be maintained because the median septa weren’t that mechanically important in a lot of these vertebrae. We use “I-beam” as a convenient shorthand to describe the shape, but in a metal I-beam the upright is as thick or thicker than the cross bits. In contrast, camerate centra of sauropod vertebrae could be more accurately described as a cylinders or boxes of bone with some holes in the sides. I think the extremely thin median septum is just a sort of developmental leftover from the process of pneumatization.

EDIT 3 days later: John Whitlock reminded me in the comments of Zurriaguz and Alvarez (2014), who looked at asymmetry in the lateral pneumatic foramina in cervical and dorsal vertebrae of titanosaurs, and found that consistent asymmetry along the cervical column was not unusual. They also explicitly hypothesized that the asymmetry was caused by diverticula on one side reaching the vertebrae earlier than diverticula on other other side. I believe they were the first to advance that idea in print (although I should probably take my own advice and scour the historical literature for any earlier instances), and needless to say, I think they’re absolutely correct.

Both of the previous images were traced from CTs, but the next one is traced from a photo of a specimen, OMNH 1882, that was broken transversely through the posterior centrum. To be honest, I’m not entirely certain what critter this vertebra is from. It is too long and the internal structure is too complex for it to be Camarasaurus. I think an apatosaurine identity is unlikely, too, given the proportional length of the surviving chunk of centrum, and the internal structure, which looks very different from CM 555 or any other apatosaur I’ve peered inside. Diplodocus and Brachiosaurus are also known from the Morrison quarries at Black Mesa, in the Oklahoma panhandle, which is where this specimen is from. Of those two, the swoopy ventral margin of the posterior centrum looks more Diplodocus-y than Brachiosaurus-y to me, and the specimen lacks the thick slab of bone that forms the ventral centrum in presacrals of Brachiosaurus and Giraffatitan (see Schwarz and Fritsch 2006: fig. 4, and this post). So on balance I think probably Diplodocus, but I could easily be wrong.

Incidentally, the photo is from 2003, before I knew much about how to properly photograph specimens. I really need to have another look at this specimen, for a lot of reasons.

Whatever taxon the vertebra is from, the internal structure is a wild scene. The median septum is off midline and bent, this time at the top rather than the bottom, the thick ventral rim of the lateral pneumatic foramen is hollow on the right but not on the left, and there are wacky chambers around the neural canal and one in the ventral floor of the centrum. 

I should point out that no-one has ever CT-scanned this specimen, and single slices can be misleading. Maybe the ventral rim of the lateral foramen is hollow just a little anterior or posterior to this slice. Possibly the median septum is more normally configured elsewhere in the centrum. But at least at the break point, this thing is crazy. 

What’s it all mean? Maybe the asymmetry isn’t noise, maybe it’s signal. We know that when bone and pneumatic epithelium get to play together, they tend to make weird stuff. Sometimes that weirdness gets constrained by functional demands, other times not so much. I think it’s very seductive to imagine sauropod vertebrae as these mechanically-optimized, perfect structures, but we have other evidence that that’s not always true (for example). Maybe as long as the articular surfaces, zygapophyses, epipophyses, neural spine tips, and cervical ribs — the mechanically-important bits — ended up in the right places, and the major laminae did a ‘good enough’ job of transmitting forces, the rest of each vertebra could just sorta do whatever. Maybe most of them end up looking more or less the same because of shared development, not because it was so very important that all the holes and flanges were in precisely the same places. That might explain why we occasionally get some really odd verts, like C11 of the Diplodocus carnegii holotype.

That’s all pretty hand-wavy and I haven’t yet thought of a way to test it, but someone probably will sooner or later. In the meantime, I think it’s valuable to just keep documenting the weirdness as we find it.

References