In mammals — certainly the most-studied vertebrates — regional differentiation of the vertebral column is distinct and easy to spot. But things aren’t so simple with sauropods. We all know that the neck of any tetrapod is made up of cervical vertebrae, and that the trunk is made up of dorsal vertebrae (subdivided into thoracic and lumbar vertebrae in the case of mammals). But how do we tell whether a given verebra is a posterior cervical or an anterior dorsal?

Here two vertabrae: a dorsal vertebra (D3) and a cervical vertebra (C13) from CM 84, the holotype of Diplodocus carnegii, modified from Hatcher (1901: plates III and VII):

It’s easy to tell these apart, even when as here we have only lateral-view images: the dorsal vertebra is tall, its centrum is short, its neural spine is anteroposteriorly compressed and its parapophysis is up on the dorsal half of the centrum; but the cervical vertebra is relatively low, its centrum is elongated, its neural spine is roughly triangular and its parapophysis hangs down well below the centrum (and has a cervical rib fused to it and the diapophysis).

But things get trickier in the shoulder region because, in sauropods at least, the transition through the last few cervicals to the first few dorsals is gradual — the vertebrae become shorter, taller and broader — and tends to have no very obvious break point. In this respect, they differ from mammals, in which the regional differentiation of the spinal column is more abrupt. (Although even here, things may not be as simple as generally assumed: for example, Gunji and Endo (2016) argued that the 1st thoracic vertebra of the giraffe behaves functionally like an 8th cervical.)

So here are those two vertebrae in context: the sequence D3 D2 D1 C15 C14 C13 in CM 84, the holotype of Diplodocus carnegii, modified from Hatcher (1901: plates III and VII):

Given that the leftmost is obviously a dorsal and the rightmost obviously a cervical, where would you place the break-point?

The most usual definition seems to be that the first dorsal vertebra is the first one that has a free rib, i.e. one not fused to the vertebra: in the illustration above, you can see that the three cervicals on the right all have their cervical ribs fused to their diapophyses and parapophyses, and the three dorsals on the left do not. This definition of the cervical/dorsal distinction seems to be widely assumed, but it is rarely explicitly asserted. (Does anyone know of a paper that lays it out for sauropods, or for dinosaurs more generally?)

But wait!

Hatcher (1903:8) — the same dude — in his Haplocanthosaurus monograph, writes:

The First Dorsal (Plate I., Fig. 1). […] That the vertebra now under consideration was a dorsal is conclusively shown not by the presence of tubercular and capitular rib facets showing that it supported on either side a free rib, for there are in our collections of sauropods, skeletons of other dinosaurs fully adult but, with the posterior cervical, bearing free cervical ribs articulating by both tubercular and capitular facets as do the ribs of the dorsal region. The character in this vertebra distinguishing it as a dorsal is the broadly expanded external border of the anterior branch of the horizontal lamina [i.e. what we would now call the centroprezygapophyseal lamina]. This element has been this modified in this and the succeeding dorsal, no doubt, as is known to be the case in Diplodocus to give greater surface for the attachment of the powerful muscles necessary for the support of the scapula.

Hatcher’s illustrations show this feature, though they don’t make it particularly obvious: here are the last two cervicals and the first dorsal, modified from Hatcher (1903:plate I), with the facet in question highlighted in pink: right lateral view at the top, then anterior, and finally posterior view at the bottom. (The facet is only visible in lateral and anterior views):

Taken at face value, Hatcher’s words here seem to imply that he considers the torso to begin where the scapula first lies alongside the vertebral column. Yet if you go back to the Diplodocus transition earlier in this post, a similar scapular facet is not apparent in the vertebra that he designated D1, and seems to be present only in D2.

Is this scapular-orientation based definition a widespread usage? Can anyone point me to other papers that use it?

Wilson (2002:226) mentions a genetic definition of the cervical/dorsal distinction

Vertebral segment identity may be controlled by a single Hox gene. The cervicodorsal transition in many tetrapods, for instance, appears to be defined by the expression boundary of the Hoxc-6 gene.

But this of course is no use in the case of extinct animals such as sauropods.

So what’s going on here? In 1964, United States Supreme Court Justice Potter Stewart, in describing his threshold test for obscenity, famously said “I shall not today attempt further to define the kinds of material I understand to be embraced within that shorthand description, and perhaps I could never succeed in intelligibly doing so. But I know it when I see it.” Is that all we have for the definition of what makes a vertebra cervicals as opposed to dorsal? We know it when we see it?

Help me out, folks! What should the test for cervical-vs-dorsal be?

References

  • Gunji, Mego, and Hideki Endo. 2016. Functional cervicothoracic boundary modified by anatomical shifts in the neck of giraffes. Royal Society Open Science 3:150604. doi:10.1098/rsos.150604
  • Hatcher, Jonathan B. 1901. Diplodocus (Marsh): its osteology, taxonomy and probable habits, with a restoration of the skeleton. Memoirs of the Carnegie Museum 1:1-63 and plates I-XIII.
  • Hatcher, J. B. 1903b. Osteology of Haplocanthosaurus with description of a new species, and remarks on the probable habits of the Sauropoda and the age and origin of the Atlantosaurus beds; additional remarks on Diplodocus. Memoirs of the Carnegie Museum 2:1-75 and plates I-VI.
  • Wilson, Jeffrey A. 2002. Sauropod dinosaur phylogeny: critique and cladistic analysis. Zoological Journal of the Linnean Society 136:217-276.

Here’s a pretty cool image: Plate 7 from Lull (1919), showing the partial skeleton of Barosaurus YPM 429 (above), compared to the much more complete skeleton of Diplodocus CM84/94 (below).

I’ve been pretty familiar with that Barosaurus skeleton diagram since I was about 9 years old, because it’s in Donald Glut’s New Dinosaur Dictionary, which I’ve written about here before. In particular, I like that Lull was scrupulous about drawing in the lateral pneumatic cavities in the caudal vertebrae. It’s pretty common in Diplodocus for the tail to be pneumatized out to somewhere between caudal 15 and 19, and the same is true in Barosaurus. I’m not just relying on the figure–Lull was also good about saying explicitly what was going on with the pneumatization in the centrum of each vertebra.

I returned to this image as an adult doing research on sauropod pneumaticity, and I read big swaths of Lull (1919), but never the bit about the sacrum. Why would I? The sacrum of YPM 429 is pretty scrappy, and I was mostly interested in the big honkin’ cervicals, and in learning how to distinguish bones of Barosaurus and Diplodocus. I always assumed that the sacrum of Barosaurus was pneumatized right the way through.

Only, er, it ain’t. As I just discovered.

Lull (1919: p. 22):

See that second sentence? “The central fragment is extremely massive, with no adaptation for lightening the weight appreciable in the portion preserved.” That’s old-timey talk for, “the chunk of centrum has no pneumatic openings or cavities”. Which is kind of a big deal, because:

…a gap of one or more apneumatic vertebrae with pneumatic vertebrae on either side constitutes a pneumatic hiatus. Why that’s a big deal is explained in this post.

If I had read this in the early 2000s, I would have flipped out. I did flip out when I discovered what seemed to be a pneumatic hiatus at the base of the tail in Haplocanthosaurus. Just that possibility sent me scurrying off to the Carnegie Museum to investigate, and precipitated both a dissertation chapter, later published as Wedel (2009), and an enduring fascination with Haplocanthosaurus. If I’d been reading Lull instead of Hatcher, my air sac paper would have been about Barosaurus, probably, and I wouldn’t have known enough about Haplo to get interested in the other specimens, which would have been a real shame.

A pneumatic hiatus in Barosaurus would have been big news in 2009. In 2021, it’s still nice, but not groundbreaking. The groundbreaking pneumatic hiatuses in Barosaurus were described in two different juvenile skeletons by Melstrom et al. (2016) and Hanik et al. (2017). Those were both mid-thoracic hiatuses, which probably separated the pneumatization domains of the cervical air sacs anteriorly and the abdominal air sacs posteriorly. A mid-sacral hiatus in YPM 429 is probably within the domain of the abdominal air sac, just like the hiatus in sacral 5 of CM 879 that I described in my 2009 paper. It’s still exciting, in that it shows that there were abdominal air sacs, and they were separate from the lungs and cervical air sacs, but this example in YPM 429 is now third in line in terms of priority, just within this one genus. Which is why I’m telling the world with a blog post, instead of hopping on a plane (or, er, planning a very long road trip) to New Haven. I’ll check on YPM 429 the next time I’m out there, but the specifics will keep for now.

References

  • Hanik, Gina M., Matthew C. Lamanna and John A. Whitlock. 2017. A juvenile specimen of Barosaurus Marsh, 1890 (Sauropoda: Diplodocidae) from the Upper Jurassic Morrison Formation of Dinosaur National Monument, Utah, USA. Annals of Carnegie Museum 84(3):253–263.
  • Lull, R.S. 1919. The sauropod dinosaur Barosaurus Marsh. Memoirs of the Connecticut Academy of Arts and Sciences 6:1-42.
  • Melstrom, Keegan M., Michael D. D’Emic, Daniel Chure and Jeffrey A. Wilson. 2016. A juvenile sauropod dinosaur from the Late Jurassic of Utah, USA, presents further evidence of an avian style air-sac system. Journal of Vertebrate Paleontology 36(4):e1111898. doi:10.1080/02724634.2016.1111898
  • Wedel, M.J. 2009. Evidence for bird-like air sacs in saurischian dinosaurs. Journal of Experimental Zoology 311A:611-628.

 

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

Figure 3. BIBE 45854, articulated series of nine mid and posterior cervical vertebrae of a large, osteologically mature Alamosaurus sanjuanensis. Series is estimated to represent the sixth to fourteenth cervical vertebrae. A, composite photo-mosaic of the cervical series in right lateral view; identification of each vertebra indicated by C6 to C14, respectively. B, line drawing based on the photo-mosaic in A. C, line drawing in B with labels shown and vertebral fossae indicated by solid grey fill; cross-hatching represents broken bone surfaces and reconstructive material. Abbreviations: C, cervical vertebra; cdf, centrodiapophyseal fossa; clf, centrum lateral fossa; pocdf, postzygapophyseal centrodiapophyseal fossa; prcdf, prezygapophyseal centrodiapophyseal fossa; prcdf1, dorsal prezygapophyseal centrodiapophyseal fossa; prcdf2, ventral prezygapophyseal centrodiapophyseal fossa; sdf, spinodiapophyseal fossa; spof, spinopostzygapophyseal fossa; sprf, spinoprezygapophyseal fossa. (Tykoski and Fiorillo 2016)

Have you been reading Justin Tweet’s series, “Your Friends the Titanosaurs“, at his awesomely-named blog, Equatorial Minnesota? If not, get on it. He’s been running the series since June, 2018, so this notice is only somewhat grotesquely overdue. The latest installment, on Alamosaurus from Texas and Mexico, is phenomenal. I have never seen another summary or review that pulled together so much of the relevant literature and explained it all so well. Seriously, that blog post deserves to be a review paper; it could be submitted pretty much as-is, although it would be even better with his two other Alamosaurus posts integrated (this one, and this one). It’s great work, is what I’m saying, and it needs to be acknowledged.

In particular, I was struck by the note by Anonymous in 1941 on the discovery of a cervical vertebra 1.2 meters long. I’d never heard of that ref, and I’ve never seen that vert, but at 120cm it would be in the top 7 longest cervical vertebrae on the planet (see the latest version of the list in this post), narrowly beating out the 118-cm cervical of Puertasaurus. In fairness, the preserved cervical of Puertasaurus is probably a posterior one, and more anterior cervicals might have been longer. Then again, in the big Alamosaurus neck the longest verts are pretty darned posterior, so…we need more Puertasaurus.

EDIT a few hours later: Thanks to the kind offices of Justin Tweet, I’ve now seen Anonymous (1941), and the exact wording is, “A single vertebra, or neck joint bone, is three feet across, only two inches less than four feet long, and in its present fossilized state weighs 600 pounds.” ‘Two inches less than four feet long’ is 46 inches or a hair under 117cm, which puts the supposed giant cervical just behind Puertasaurus after all, but still firmly in the top 10. And depending on how one interprets the passage in Anonymous (1941), it might not have been any bigger than BIBE 45854–see this comment for details.

Big cervical showdown. From the top left: BYU 9024, originally referred to Supersaurus but more likely representing a giant Barosaurus (137cm); the single available cervical of Puertasaurus (118cm); a world-record giraffe neck (2.4m); Alamosaurus referred cervical series BIBE 45854, longest centra are ~81cm; Sauroposeidon holotype OMNH 53062, longest centrum is 125cm. This image makes it very clear that whatever Sauroposeidon was doing, it was a way different thing from Alamosaurus.

Crucially, the longest vertebrae in the BIBE 45854 series are about 80 or 81 cm long, which means that a 1.2-meter cervical would be half again as large. That is a pretty staggering thought, and that individual of Alamosaurus–assuming it was the same taxon as BIBE 45854, and not some other, longer-necked critter–would definitely be a contender for the largest sauropod of all time.

Illustrations here are of the big Alamosaurus cervical series from Big Bend, which was comprehensively described by Ron Tykoski and Tony Fiorillo in 2016, and which we have covered in these previous posts:

References

  • Anonymous. 1941. Find dinosaur neck bone nearly four feet long. The Science News-Letter 39(1):6–7.
  • Tykoski, R.S. and Fiorillo, A.R. 2016. An articulated cervical series of Alamosaurus sanjuanensis Gilmore, 1922 (Dinosauria, Sauropoda) from Texas: new perspective on the relationships of North America’s last giant sauropod. Journal of Systematic Palaeontology 15(5):339-364.

Today marks the one-month anniversary of my and Matt’s paper in Qeios about why vertebral pneumaticity in sauropods is so variable. (Taylor and Wedel 2021). We were intrigued to publish on this new platform that supports post-publication peer-review, partly just to see what happened.

Taylor and Wedel (2021: figure 3). Brontosaurus excelsus holotype YPM 1980, caudal vertebrae 7 and 8 in right lateral view. Caudal 7, like most of the sequence, has a single vascular foramen on the right side of its centrum, but caudal 8 has two; others, including caudal 1, have none.

So what has happened? Well, as I write this, the paper has been viewed 842 times, downloaded a healthy 739 times, and acquired an altmetric score 21, based rather incestuously on two SV-POW! blog-posts, 14 tweets and a single Mendeley reader.

What hasn’t happened is even a single comment on the paper. Nothing that could be remotely construed as a post-publication peer-review. And therefore no progress towards our being able to count this as a peer-reviewed publication rather than a preprint — which is how I am currently classifying it in my publications list.

This, despite our having actively solicited reviews both here on SV-POW!, in the original blog-post, and in a Facebook post by Matt. (Ironically, the former got seven comments and the latter got 20, but the actual paper none.)

I’m not here to complain; I’m here to try to understand.

On one level, of course, this is easy to understand: writing a more-than-trivial comment on a scholarly article is work, and it garners very little of the kind of credit academics care about. Reputation on the Qeios site is nice, in a that-and-two-bucks-will-buy-me-a-coffee kind of way, but it’s not going to make a difference to people’s CVs when they apply for jobs and grants — not even in the way that “Reviewed for JVP” might. I completely understand why already overworked researchers don’t elect to invest a significant chunk of time in voluntarily writing a reasoned critique of someone else’s work when they could be putting that time into their own projects. It’s why so very few PLOS articles have comments.

On the other hand, isn’t this what we always do when we write a solicited peer-review for a regular journal?

So as I grope my way through this half-understood brave new world that we’re creating together, I am starting to come to the conclusion that — with some delightful exceptions — peer-review is generally only going to happen when it’s explicitly solicited by a handling editor, or someone with an analogous role. No-one’s to blame for this: it’s just reality that people need a degree of moral coercion to devote that kind of effort to other people’s project. (I’m the same; I’ve left almost no comments on PLOS articles.)

Am I right? Am I unduly pessimistic? Is there some other reason why this paper is not attracting comments when the Barosaurus preprint did? Teach me.

References

 

This is RAM 1619, a proximal caudal vertebra of an apatosaurine, in posterior view. It’s one of just a handful of sauropod specimens at the Raymond M. Alf Museum of Paleontology. It’s a donated specimen, which came with very little documentation. It was originally catalogued only to a very gross taxonomic level, but I had a crack at it on a collections visit in 2018, when I took these photos. I told Andy Farke and the other Alf folks right away, I just never got around to blogging about it until now.

Why do I think it’s an apatosaurine? A few reasons: 

  • it’s slightly procoelous, which is pretty common for diplodocids, whereas caudals of Haplocanthosaurus, Camarasaurus, and Brachiosaurus are all either amphicoelous or amphiplatyan;
  • it has big pneumatic fossae above the transverse processes, unlike Haplo, Cam, and Brachio, but it lacks big pneumatic fossae below the transverse processes, unlike Diplodocus and Barosaurus
  • and finally the clincher: the centrum is taller than wide, and broader dorsally than ventrally.

In the literature this centrum shape is described as ‘heart-shaped’ (e.g., Tschopp et al. 2015), and sometimes there is midline dorsal depression that really sells it. That feature isn’t present in this vert, but overall it’s still much closer to a heart-shape than the caudals of any non-apatosaurine in the Morrison. Hence the literal 11th-hour Valentine’s Day post (and yes, this will go up with a Feb. 15 date because SV-POW! runs on England time, but it’s still the 14th here in SoCal, at least for another minute or two).

RAM 1619 in postero-dorsal view.

Back to the pneumaticity. Occasionally an apatosaurine shows up with big lateral fossae ventral to the transverse processes–the mounted one at the Field Museum is a good example (see this post). And the big Oklahoma apatosaurine breaks the rules by having very pneumatic caudals–more on that in the future. But at least in the very proximal caudals of non-gigantic apatosaurines, it’s more common for there to be pneumatic fossae above the transverse processes, near the base of the neural arch. You can see that in caudal 3 of UWGM 15556/CM 563, a specimen of Brontosaurus parvus:

I don’t think I’d figured out this difference between above-the-transverse-process (supracostal, perhaps) and below-the-transverse-process (infracostal, let’s say) pneumatic fossae when Mike and I published our caudal pneumaticity paper back in 2013. I didn’t start thinking seriously about the dorsal vs ventral distribution of pneumatic features until sometime later (see this post). And I need to go check my notes and photos before I’ll feel comfortable calling supracostal fossae the apatosaurine norm. But I am certain that Diplodocus and Barosaurus have big pneumatic foramina on the lateral faces of their proximal caudals (see this post, for example), Haplocanthosaurus and brachiosaurids have infracostal fossae when they have any fossae at all in proximal caudals (distally the fossae edge up to the base of the neural arch in Giraffatitan), and to date there are no well-documented cases of caudal pneumaticity in Camarasaurus (if that seems like a hedge, sit tight and W4TP). 

RAM 1619 has asymmetric pneumatic fossae, which is pretty cool, and also pretty common, and we think we have a hypothesis to explain that now–see Mike’s and my new paper in Qeios.

And if I’m going to make my midnight deadline, even on Pacific Time, I’d best sign off. More cool stuff inbound real soon.

References

Gilmore (1936:243) says of the mounted skeleton of Apatosaurus louisae CM 3018 in the Carnegie Museum that “with the skull in position the specimen has a total length between perpendiculars of about 71 feet and six inches. If the missing eighteen terminal caudal vertebrae were added to the tip of the tail, in order to make it conform to known evidence, the skeleton will reach an estimated length of 76 feet, 6 inches.” That’s 23.3 meters.

But what if it was 800 meters long instead? That would be 34.3 times as big in linear dimension (and so would mass 34.3^3 = 40387 time as much, perhaps a million tonnes — but that’s not my point).

What would a cervical vertebra of an 800m sauropod look like?

Gilmore (1936:196) gives the centrum length of CM 3018’s C10 as 530 mm. In our 34.3 times as long Apatosaurus, it would be 18.17 meters long. So here is what that would look like compared with two London Routemaster buses (each 8.38 meters long).

Cervical vertebra 10 of a hypothetical 800 meter long Apatosaurus louisae, with London Routemaster buses for scale. Vertebra image from Gilmore 1936:plate XXIV; bus image by Graham Todman, from Illustrations for t-shirts.

What is the research significance of this? None at all, of course. Still I think further study is warranted. Some look at sauropods that once were, and ask “why?”; but I go further; I look at sauropods that never were, and ask “why not?”

 

It’s been a minute, hasn’t it?

Up top, C10 and C11 of Diplodocus carnegii CM 84, from Hatcher (1901). Below, C9 and C10 of Apatosaurus louisae CM 3018, from Gilmore (1936). The Diplodocus verts are in right lateral view but reversed for ease of comparison, and the Apatosaurus verts are in left lateral view. Both sets scaled to the same cumulative centrum length. Just in case you forgot that apatosaurines are redonkulous.

References

  • Hatcher, John Bell. 1901. Diplodocus (Marsh): its osteology, taxonomy, and probable habits, with a restoration of the skeleton. Memoirs of the Carnegie Museum 1:1-63.
  • Gilmore, Charles Whitney. 1936. Osteology of Apatosaurus, with special reference to specimens in the Carnegie Museum. Memoirs of the Carnegie Museum 11:175–300.

This is a very belated follow-up to “Tutorial 12: How to find problems to work on“, and it’s about how to turn Step 2, “Learn lots of stuff”, into concrete progress. I’m putting it here, now, because I frequently get asked by students about how to get started in research, and I’ve been sending them the same advice for a while. As with Tutorial 25, from now on I can direct the curious to this post, and spend more time talking with them about what they’re interested in, and less time yakking about nuts and bolts. But I hope the rest of you find this useful, too.

Assuming, per Tutorial 12, that you’ve picked something to investigate–or maybe you’re trying to pick among things to investigate–what next? You need a tractable way to get started, to organize the things you’re learning, and to create a little structure for yourself. My recommendation: do a little project, with the emphasis on little. Anyone can do this, in any area of human activity. Maybe your project will be creating a sculpture, shooting and editing a video, learning–or creating–a piece of music, or fixing a lawn mower engine. My central interest is how much we still have to discover about the natural world, so from here on I’m going to be writing as a researcher addressing other researchers, or aspiring researchers.

Arteries of the anterior leg, from Gray’s Anatomy (1918: fig. 553). Freely available courtesy of Bartleby.com.

I’ll start with a couple of examples, both from my own not-too-distant history. A few years ago I got to help some of my colleagues from the College of Podiatric Medicine with a research project on the perforating branch of the peroneal artery (Penera et al. 2014). I knew that vessel from textbooks and atlases and from having dissected a few out, but I had never read any of the primary (journal) literature on it. As the designated anatomist on the project, I needed to write up the anatomical background. So I hit the journals, tracked down what looked like the most useful papers, and wrote a little 2-page summary. We didn’t use all of it in the paper, and we didn’t use it all in one piece. Some sentences went into the Introduction, others into the Discussion, and still others got dropped entirely or cut way down. But it was still a tremendously useful exercise, and in cases like this, it’s really nice to have more written down than you actually need. Here’s that little writeup, in case you want to see what it looks like:

Wedel 2013 anatomy of the perforating branch of the peroneal artery

Pigeon spinal cord cross-section, from Necker (2006: fig. 4).

More recently, when I started working with Jessie Atterholt on weird neural canal stuff in dinosaurs, I realized that I needed to know more about glycogen bodies in birds, and about bird spinal cords generally. I expected that to be quick and easy: read a couple of papers, jot down the important bits, boom, done. Then I learned about lumbosacral canals, lobes of Lachi, the ‘ventral eminences’ of the spinal cord in ostriches, and more, a whole gnarly mess of complex anatomy that was completely new to me. I spent about a week just grokking all the weird crap that birds have going on in their neural canals, and realized that I needed to crystallize my understanding while I had the whole structure in my head. Otherwise I’d come back in a few months and have to learn it all over again. Because it was inherently visual material, this time I made a slide deck rather than a block of text, something I could use to get my coauthors up to speed on all this weirdness, as well as a reminder for my future self. Here’s that original slide deck:

Wedel 2018 Avian lumbosacral spinal cord specializations

If you’re already active in research, you may be thinking, “Yeah, duh, of course you write stuff down as you get a handle on it. That’s just learning.” And I agree. But although this may seem basic, it isn’t necessarily obvious to people who are just starting out. And even to the established, it may not be obvious that doing little projects like this is a good model for making progress generally. Each one is a piton driven into the mountainside that I’m trying to climb: useful for me, and assuming I get them out into the world, useful for anyone I’d like to come with me (which, for an educator and a scientist, means everyone).

A view down the top of the vertebral column in the mounted skeleton of Apatosaurus louisae, CM 3018, showing the trough between the bifurcated neural spines.

If you’re not active in research, the idea of writing little term papers may sound like purgatory. But writing about something that you love, that fascinates you, is a very different proposition from writing about dead royalty or symbolism because you have to for a class.* I do these little projects for myself, to satisfy my curiosity, and it doesn’t feel like work. More like advanced play. When I’m really in the thick of learning a new thing–and not, say, hesitating on the edge before I plunge in–I am so happy that I tend to literally bounce around like a little kid, and the only thing that keeps me sitting still is the lure of learning the next thing. That I earn career beans for doing this still seems somewhat miraculous, like getting paid to eat ice cream.

* YMMV, history buffs and humanities folks. If dead royalty and symbolism rock your world but arteries and vertebrae leave you cold, follow your star, and may a thousand gardens grow.

Doing little projects is such a convenient and powerful way to make concrete progress that it has become my dominant mode. As with the piece that I wrote about the perforating branch of the peroneal artery, the products rarely get used wholesale in whatever conference presentation or research paper I end up putting together, but they’re never completely useless. First, there is the benefit to my understanding that I get from assembling them. Second, they’re useful for introducing other people to the sometimes-obscure stuff I work on, and nothing makes you really grapple with a problem like having to explain it to others. And third, these little writeups and slideshows become the Lego bricks from which I assemble future talks and papers. The bird neural canal slide deck became a decent chunk of our presentation on the Snowmass Haplocanthosaurus at the 1st Palaeontological Virtual Congress (Wedel et al. 2018)–and it’s about to become something even better. (Four months later: it did!)

The operative word at the start of the last paragraph is ‘concrete’. I don’t think this was always the case, but now that I’m in my mid-40s ‘what I know’ is basically equivalent to ‘what I remember’, which is basically equivalent to ‘what I’ve written down’. (And sometimes not even then–Mike and I both run across old posts here on SV-POW! that we’ve forgotten all about, which is a bit scary, given how often we put novel observations and ideas into blog posts.) Anyway, this is why I like the expression ‘crystallize my understanding’: the towers of comprehension that I build in my head are sand castles, and if I don’t find a way to freeze them in place, they will be washed away by time and my increasingly unreliable cerebral machinery.

Really nice Stegosaurus plate on display at Dinosaur National Monument.

Also, if I divide my life into the things I could do and the things I have done, only the things in the latter category are useful. So if you are wondering if it’s worthwhile to write a page to your future self about valves in the cerebral arteries of rats, or all of the dinosaurs from islands smaller than Great Britain, or whatever strange thing has captured your attention, I say yes, go for it. Don’t worry about finding something novel to say; at the early stages you’re just trying to educate yourself (also, talks and papers need intro and background material, so you can still get credit for your efforts). I’ll bet that if you set yourself the goal of creating a few of these–say, one per year, or one per semester–you’ll find ways to leverage them once you’ve created them. If all else fails, start a blog. That might sound flip, but I don’t mean for it to. I got my gig writing for Sky & Telescope because I’d been posting little observing projects for the readers of my stargazing blog.

A final benefit of doing these little projects: they’re fast and cheap, like NASA’s Discovery missions. So they’re a good way to dip your toes into a new area before you commit to something more involved. The more things you try, the more chances you have to discover whatever it is that’s going to make you feel buoyantly happy.

You may have noticed that all of my examples in this post involved library research. That’s because I’m particularly interested in using little projects to get started in new lines of inquiry, and whenever you are starting out in a new area, you have to learn where the cutting edge is before you can move it forward (Tutorial 12 again). Also, as a practical consideration, most of us are stuck with library research right now because of the pandemic. Obviously this library research is no substitute for time in the lab or the field, but even cutters and diggers need to do their homework, and these little projects are the best way that I’ve found of doing that.

P.S. If you are a student, read this and do likewise. And, heck, everyone else who writes should do that, too. It is by far the advice I give most often as a journal editor and student advisor.

P.P.S. As long as you’re reading Paul Graham, read this piece, too–this whole post was inspired by the bit near the end about doing projects.

References

Cool URIs don’t change

November 26, 2020

It’s now 22 years since Tim Berners-Lee, inventor of the World Wide Web, wrote the classic document Cool URIs don’t change [1]. It’s core message is simple, and the title summarises it. Once an organization brings a URI into existence, it should keep it working forever. If the document at that URI moves, then the old URI should become a redirect to the new. This really is Web 101 — absolute basics.

So imagine my irritation when I went to point a friend to Matt’s and my 2013 paper on whether neural-spine bifurcation is an ontogenetic character (spoiler: no), only to find that the paper no longer exists.

Wedel and Taylor (2013b: figure 15). An isolated cervical of cf. Diplodocus MOR 790 8-10-96-204 (A) compared to D. carnegii CM 84/94 C5 (B), C9 (C), and C12 (D), all scaled to the same centrum length. Actual centrum lengths are 280 mm, 372 mm, 525 mm, and 627 mm for A-D respectively. MOR 790 8-10-96-204 modified from Woodruff & Fowler (2012: figure 2B), reversed left to right for ease of comparison; D. carnegii vertebrae from Hatcher (1901: plate 3).

Well — it’s not quite that bad. I was able to go to the web-site’s home page, navigate to the relavant volume and issue, and find the new location of our paper. So it does still exist, and I was able to update my online list of publications accordingly.

But seriously — this is a really bad thing to do. How many other links might be out there to our paper? All of them are now broken. Every time someone out there follows a link to a PalArch paper — maybe wondering whether that journal would be a good match for their own work — they are going to run into a 404 that says “We can’t run our website properly and can’t be trusted with your work”.

“But Mike, we need to re-organise our site, and —” Ut! No. Let’s allow Sir Tim to explain:

We just reorganized our website to make it better.

Do you really feel that the old URIs cannot be kept running? If so, you chose them very badly. Think of your new ones so that you will be able to keep then running after the next redesign.

Well, we found we had to move the files…

This is one of the lamest excuses. A lot of people don’t know that servers such as Apache give you a lot of control over a flexible relationship between the URI of an object and where a file which represents it actually is in a file system. Think of the URI space as an abstract space, perfectly organized. Then, make a mapping onto whatever reality you actually use to implement it. Then, tell your server.

If you are a responsible organization, then one of the things you are responsible for is ensuring that you don’t break inbound links. If you want to reorganize, fine — but add the redirects.

And look, I’m sorry, I really don’t want to pick on PalArch, which is an important journal. Our field really needs diamond OA journals: that is, venues where vertebrate paleontology articles are free to read and also free to authors. It’s a community-run journal that is not skimming money out of academia for shareholders, and Matt’s and my experience with their editorial handling was nothing but good. I recommend them, and will proabably publish there again (despite my current irritation). But seriously, folks.

And by the way, there are much worse offenders than PalArch. Remember Aetogate, the plagiarism-and-claim-jumping scandal in New Mexico that the SVP comprehensively fudged its investigation of? The documents that the SVP Ethics Committee produced, such they were, were posted on the SVP website in early 2008, and my blog-post linked to them. By July, they had moved, and I updated my links. By July 2013, they had moved again, and I updated my links again. By October 2015 they had moved for a third time: I both updated my links, and made my own copy in case they vanished. Sure enough, by February 2019 they had gone again — either moved for a fourth time or just quietly discarded. This is atrocious stewardship by the flagship society of our discipline, and they should be heartily ashamed that in 2020, anyone who wants to know what they concluded about the Aetogate affair has to go and find their documents on a third-party blog.

Seriously, people! We need to up our game on this!

Cool URIs don’t change.

 

 


[1] Why is this about URIs instead of URLs? In the end, no reason. Technically, URIs are a broader category than URLs, and include URNs. But since no-one anywhere in the universe has ever used a URN, in practice URL and URI are synonymous; and since TBL wrote his article in 1998, “URL” has clearly won the battle for hearts and minds and “URI” has diminished and gone into the West. If you like, mentally retitle the article “Cool URLs don’t change”.