We’ve noted many times over the years how inconsistent pneumatic features are in sauropod vertebra. Fossae and formamina vary between individuals of the same species, and along the spinal column, and even between the sides of individual vertebrae. Here’s an example that we touched on in Wedel and Taylor (2013), but which is seen in all its glory here:
Taylor and Wedel (2021: Figure 5). Giraffatitan brancai tail MB.R.5000, part of the mounted skeleton at the Museum für Naturkunde Berlin. Caudal vertebrae 24–26 in left lateral view. While caudal 26 has no pneumatic features, caudal 25 has two distinct pneumatic fossae, likely excavated around two distinct vascular foramina carrying an artery and a vein. Caudal 24 is more shallowly excavated than 25, but may also exhibit two separate fossae.
But bone is usually the least variable material in the vertebrate body. Muscles vary more, nerves more again, and blood vessels most of all. So why are the vertebrae of sauropods so much more variable than other bones?
Our new paper, published today (Taylor and Wedel 2021) proposes an answer! Please read it for the details, but here’s the summary:
- Early in ontogenly, the blood supply to vertebrae comes from arteries that initially served the spinal cord, penetrating the bone of the neural canal.
- Later in ontegeny, additional arteries penetrate the centra, leaving vascular foramina (small holes carrying blood vessels).
- This hand-off does not always run to completion, due to the variability of blood vessels.
- In extant birds, when pneumatic diverticula enter the bone they do so via vascular foramina, alongside blood vessels.
- The same was probaby true in sauropods.
- So in vertebrae that got all their blood supply from vascular foramina in the neural canal, diverticula were unable to enter the centra from the outside.
- So those centra were never pneumatized from the outside, and no externally visible pneumatic cavities were formed.
Somehow that pretty straightforward argument ended up running to eleven pages. I guess that’s what you get when you reference your thoughts thoroughly, illustrate them in detail, and discuss the implications. But the heart of the paper is that little bullet-list.
Taylor and Wedel (2021: Figure 6). Domestic duck Anas platyrhynchos, dorsal vertebrae 2–7 in left lateral view. Note that the two anteriormost vertebrae (D2 and D3) each have a shallow pneumatic fossa penetrated by numerous small foramina.
(What is the relevance of these duck dorsals? You will need to read the discussion in the paper to find out!)
Our choice of publication venue
The world moves fast. It’s strange to think that only eleven years ago my Brachiosaurus revision (Taylor 2009) was in the Journal of Vertebrate Palaeontology, a journal that now feels very retro. Since then, Matt and I have both published several times in PeerJ, which we love. More recently, we’ve been posting preprints of our papers — and indeed I have three papers stalled in peer-review revisions that are all available as preprints (two Taylor and Wedels and a single sole-authored one). But this time we’re pushing on even further into the Shiny Digital Future.
We’ve published at Qeios. (It’s pronounced “chaos”, but the site doesn’t tell you that; I discovered it on Twitter.) If you’ve not heard of it — I was only very vaguely aware of it myself until this evening — it runs on the same model as the better known F1000 Research, with this very important difference: it’s free. Also, it looks rather slicker.
That model is: publish first, then filter. This is the opposite of the traditional scholarly publishing flow where you filter first — by peer reviewers erecting a series of obstacles to getting your work out — and only after negotiating that course to do get to see your work published. At Qeios, you go right ahead and publish: it’s available right off the bat, but clearly marked as awaiting peer-review:
And then it undergoes review. Who reviews it? Anyone! Ideally, of course, people with some expertise in the relevant fields. We can then post any number of revised versions in response to the reviews — each revision having its own DOI and being fixed and permanent.
How will this work out? We don’t know. It is, in part, an experiment. What will make it work — what will impute credibility to our paper — is good, solid reviews. So if you have any relevant expertise, we do invite you to get over there and write a review.
And finally …
Matt noted that I first sent him the link to the Qeios site at 7:44 pm my time. I think that was the first time he’d heard of it. He and I had plenty of back and forth on where to publish this paper before I pushed on and did it at Qeios. And I tweeted that our paper was available for review at 8:44 — one hour exactly after Matt learned that the venue existed. Now here we are at 12:04 my time, three hours and 20 minutes later, and it’s already been viewed 126 times and downloaded 60 times. I think that’s pretty awesome.
References
- Taylor, Michael P. 2009. A re-evaluation of Brachiosaurus altithorax Riggs 1903 (Dinosauria, Sauropoda) and its generic separation from Giraffatitan brancai (Janensch 1914). Journal of Vertebrate Paleontology 29(3):787-806. [PDF]
- Taylor, Michael P., and Mathew J. Wedel. 2021. Why is vertebral pneumaticity in sauropod dinosaurs so variable? Qeios 1G6J3Q. doi: 10.32388/1G6J3Q [PDF]
- Wedel, Mathew J., and Michael P. Taylor 2013b. Caudal pneumaticity and pneumatic hiatuses in the sauropod dinosaurs Giraffatitan and Apatosaurus. PLOS ONE 8(10):e78213. 14 pages. doi: 10.1371/journal.pone.0078213 [PDF]
You! Shall not! Pass!
August 22, 2020
OK, technically this is MB.R.3822, a dorsal vertebra of Giraffatitan brancai formerly known as HMN Ar1, in posterior view, rendered from a 3D scan provided by Heinrich Mallison.
But you can’t tell me that when you look at that you don’t see Gandalf shouting at a balrog.
Long before Matt and others were CT-scanning sauropod vertebrae to understand their internal structure, Werner Janensch was doing it the old-fashioned way. I’ve been going through old photos that I took at the Museum für Naturkunde Berlin back in 2005, and I stumbled across this dorsal centrum:
Dorsal vertebra centum of ?Giraffatitan in ventral view, with anterior to top.
You can see a transverse crack running across it, and sure enough the front and back are actually broken apart. Here there are:
The same dorsal vertebral centrum of ?Giraffatitan, bisected transversely in two halves. Left: anterior half in posterior view; right: posterior half in anterior view. I had to balance the anterior half on my shoe to keep it oriented corrrectly for the photo.
This does a beautiful job of showing the large lateral foramina penetrating into the body of the centrum and ramifying further into the bone, leaving only a thin midline septum.
But students of the classics will recognise this bone immediately as the one that Janensch (1947:abb. 2) illustrated the posterior half of in his big pneumaticity paper:
It’s a very strange feeling, when browsing in a collection, to come across a vertebra that you know from the literature. As I’ve remarked to Matt, it’s a bit like running into, say, Cameron Diaz in the corner shop.
Reference
- Janensch, W. 1947. Pneumatizitat bei Wirbeln von Sauropoden
und anderen Saurischien. Palaeontographica, supplement
7:1-25.
The SV-POW! Patreon adds a tier
February 18, 2020
I swear I’m not making this up: I was recently contacted by one of our patrons, who said he’d like to support us at the SV-POW! Patreon at $10/month. We didn’t have that tier at the time, only $1/mo. and $5/mo. So to accommodate him, and any others who theoretically might like to support us at that level, we created a $10 tier. There’s a new reward to go with this tier: in addition to being acknowledged in any papers that get written as a result of a trip that you help to fund, at $10/month you’ll also get an 8×10 art print once a year, either one of my skull drawings or a photograph, signed or unsigned. Here’s the link.
Our support is up to $57/mo. That might not sound like much, but $7/mo. is $84/yr., which is what we wanted when Mike launched the Patreon so we could get rid of ads on the site. The other $50/mo. is $600/yr., which is roughly the cost of a trans-Atlantic plane ticket. So that’s already one Matt-and-Mike get-together a year to do research and write papers, in addition to any others we were going to do anyway.
What would we do with more support? More research, and more writing. I get small grants now and then, and I get a yearly travel budget from my department, but grant-writing takes time away from research and paper-writing, and the departmental travel money doesn’t cover all the things I’d like to do. For example, I skipped SVPCA in 2018 so I could visit the Carnegie last spring. That’s a tough choice, a whole conference worth of ideas and conversations that I missed out on. And Mike is basically self-funded. We’re pretty good at converting travel money into new ideas and new data, and we’re going to start doing writing retreats where we hole up someplace cheap, far from museums, field sites, and other distractions, and just write. So if you like the stuff we do, please consider supporting us–we promise not to waste your donation.
Many thanks to everyone who supports our work, and to everyone else for sitting through this post. In the spirit of giving you more than you asked for, up top is the cervicodorsal transition in Giraffatitan brancai, MB.R.2181, in my favorite, inconvenient portrait orientation. And here’s a version with the centrum lengths and posterior widths given in cm. From Janensch (1950: figs. 49 and 50).
Reference
Janensch, Werner. 1950. Die Wirbelsaule von Brachiosaurus brancai. Palaeontographica (Suppl. 7) 3: 27-93.
Nature’s CT machine
January 28, 2020
Because I’ve worked a lot on the anatomy and evolution of air-filled bones in sauropod dinosaurs, I’ve spent most of my career looking at images like this:
CT sections through a cervical vertebra of an apatosaurine (Apatosaurus or Brontosaurus), OMNH 1094. Wedel (2003b: fig. 6). Scale bar is 10cm.
…and thinking about images like this:
Physical sections through pneumatic vertebrae of Giraffatitan. Janensch (1950: figs. 71-73).
Turns out, that’s pretty good practice for fossil prospecting in the Salt Wash member of the Morrison Formation, where we frequently find things like this:
That’s a bit hard to read, so let’s pull it out from the background:
This is almost certainly a pneumatic vertebra of a sauropod, sectioned more-or-less randomly by the forces of erosion to expose a complicated honeycomb of internal struts and chambers. The chambers are full of sandstone now, but in life they were full of air. I say “almost certainly” because there is small chance that it could belong to a very large theropod, but it looks more sauropod-y to me (for reasons I may expand upon in the comments if anyone is curious).
I’m not 100% certain what section this is. At first I was tempted to read it as a transversely-sectioned dorsal, something like the Allosaurus dorsal shown in this post (link) but from a small, possibly juvenile sauropod. But the semi-radial, spoke-like arrangement of the internal struts going to the round section at the bottom looks very much like the inside of the condyle of a sauropod cervical or cervico-dorsal–compare to fig. 71 from Janensch (1950), shown above. And of course there is no reason to suspect that the plane of this cut is neatly in any of the cardinal anatomical directions. It is most likely an oblique cut that isn’t purely transverse or sagittal or anything else, but some combination of the above. It’s also not alone–there are bits and bobs of bone to the side and above in the same chunk of sandstone, which might be parts of this vertebra or of neighboring bones. Assuming it is a sauropod, my guess is Diplodocus or Brachiosaurus, because it looks even more complex than the sectioned cervicals and dorsals I’ve seen of Haplocanthosaurus, Camarasaurus, or the apatosaurines.
Sometimes we can do a little better. This is one of my favorite finds from the Salt Wash. This boulder, now in two parts, fell down out of a big overhanging sandstone cliff. When the boulder hit, it broke into two halves, and the downhill half rolled over 180 degrees, bringing both cut faces into view in this photo. And there in the boulder is what looks like two vertebrae, but is in fact the neatly separated halves of a single vertebra. I know I refer to erosion and breakage as “Nature’s CT machine”, but this time that’s really on the nose. Let’s take a closer look:
Here’s what I see:
It’s a proportionally long vertebra with a round ball at one end and a hemispherical socket at the other end: a cervical vertebra of a sauropod. Part of the cervical rib is preserved on the upper side, which I suspect is the left side. The parapophysis on the opposite side is angled a bit out of the rock, toward the camera. Parapophyses of sauropod cervicals tend to be angled downward, and if we’re looking at the bottom of this vertebra, then the rib on the upper side is the left. The right cervical rib was cut off when the boulder broke. All we have on this side are the wide parapophysis and the slender strut of the diapophysis aiming out of the rock toward the missing rib, which must still be embedded in the other half of the boulder–and in fact you can see a bit of it peeking out in the counterpart in the wide shot, above.
Can we get a taxonomic ID? I think so, based on the following clues:
- The cervical ribs are set waaay out to either side of the centrum, by about one centrum diameter. Such wide-set cervical ribs occur in Camarasaurus and the apatosaurines, Apatosaurus and Brontosaurus, but not typically in Diplodocus, Brachiosaurus, or other Morrison sauropods.
- The cervical rib we can see the most of is pretty slender, like those of Camarasaurus, in contrast to the massive, blocky cervical ribs of the apatosaurines (for example).
- We can see at least bits of both the left and right cervical ribs in the two slabs–along with a section right through the centrum. So the cervical ribs were set wide from the centrum but not displaced deeply below it, as in Camarasaurus, and again in contrast to the apatosaurines, in which the cervical ribs are typically displaced far below (ventral to) the centrum (see this).
- This one is a little more loosey-goosey, but the exposed internal structure looks “about right” for Camarasaurus. There is a mix of large and small chambers, but not many small ones, and nothing approaching the coarse, regular honeycomb we’d expect in Apatosaurus, Brontosaurus, or Diplodocus, let alone the fine irregular honeycomb we’d expect in Barosaurus or Brachiosaurus (although I will show you a vert like that in an upcoming post). On the other hand, the internal structure is too complex for Haplocanthosaurus (compare to the top image here).
- As long as Camarasaurus is on the table, I’ll note that the overall proportions are good for a mid-cervical of Cam as well. That’s not worth much, since vertebral proportions vary along the column and almost every Morrison sauropod has cervicals with this general proportion somewhere in the neck, but it doesn’t hurt.
So the balance of the evidence points toward Camarasaurus. In one character or another, every other known Morrison sauropod is disqualified.
When it’s too dark to hunt for sauropods, you can look at other things.
Now, Camarasaurus is not only the most common sauropod in the Morrison, it’s also the most common dinosaur of any kind in the formation. So this isn’t a mind-blowing discovery. Still, it’s nice to be able to get down to a genus-level ID based on a single vertebra fortuitously sectioned by Mother Nature. In upcoming posts, I’ll show some of the more exciting critters that we’ve been able to ID out of the Salt Wash, ‘we’ here including Brian Engh, John Foster, ReBecca Hunt-Foster, Jessie Atterholt, and Thuat Tran. Brian will also be showing many of these same fossils in the next installment of Jurassic Reimagined. Catch Part 1 here (link), and stay tuned to Brian’s paleoart channel (here) for more in the very near future.
References
- Janensch, Werner. 1950. Die Wirbelsaule von Brachiosaurus brancai. Palaeontographica (Suppl. 7) 3: 27-93.
- Wedel, M.J. 2003b. The evolution of vertebral pneumaticity in sauropod dinosaurs. Journal of Vertebrate Paleontology 23: 344-357.
The Day of the Dinosaur, and the legend of the regrown sauropod tail
October 17, 2019
Two professionals, hard at work.
After this year’s SVPCA, Vicki and London and I spent a few days with the Taylor family in the lovely village of Ruardean. It wasn’t all faffing about with the Iguanodon pelvis, the above photo notwithstanding. Mike and I had much to discuss after the conference, in particular what the next steps might be for the Supersaurus project. Mike has been tracking down early mentions of Supersaurus, and in particular trying to determine the point at which Jensen decided that it might be a diplodocid rather than a brachiosaurid. I recalled that Gerald Wood discussed Supersaurus in his wonderful 1982 book, The Guinness Book of Animal Facts and Feats. While on the track of Supersaurus, I stumbled across this amazing claim in the section on Diplodocus (Wood 1982: p. 209):
According to De Camp and De Camp (1968) these giant sauropods may have been able to regenerate lost parts, and they mention another skeleton collected in Wyoming which appeared to have lost about 25 per cent of its tail to a carnosaur and then regrown it — along with 21 new vertebrae!
De Camp and De Camp (1968) is a popular or non-technical book, The Day of the Dinosaur. Used copies can be had for a song, so I ordered one online and it was waiting for me when I got back to California.
The Day of the Dinosaur is an interesting book. L. Sprague De Camp and Catherine Crook De Camp embodied the concept of the “life-long learner” before there was a buzzword to go with it. He had been an aerospace engineer in World War II, and she had been an honors graduate and teacher, before they turned to writing full time. Individually and together, they produced a wide range of science fiction, fantasy, and nonfiction books over careers that spanned almost six decades. The De Camps’ writing in The Day of the Dinosaur is erudite in range but conversational in style, and they clearly kept up with current discoveries. They also recognized that science is a human enterprise and that, like any exploratory process, it is marked by wildly successful leaps, frustrating wheel-spinning, and complete dead ends. I was pleasantly surprised to find that the authors were completely up to speed on plate tectonics, an essentially brand-new science in 1968, and they explain it as an alternative to older theories about immensely long land bridges or sunken continents.
At the same time, the book arrived just before the end-of-the-1960s publications of John Ostrom and Bob Bakker that kicked off the Dinosaur Renaissance, so there’s no mention of warm-blooded dinosaurs. The De Camps’ sauropods and duckbills are still swamp-bound morons, “endlessly dredging up mouthfuls of soft plant food and living out their long, slow, placid, brainless lives” (p. 142), stalked by ‘carnosaurs’ that were nothing more than collections of teeth relentlessly driven by blind instinct and hunger. The book is therefore an artifact of a precise time; there was perhaps a year at most in the late 1960s when authors as technically savvy as the De Camps would have felt obliged to explain plate tectonics and its nearly-complete takeover of structural geology (which had just happened), but not to comment on the new and outrageous hypothesis of warm-blooded, active, terrestrial dinosaurs (which hadn’t happened yet).
The book may also appeal to folks with an interest in mid-century paleo-art, as the illustrations are a glorious hodge-podge of Charles R. Knight, Neave Parker, photos of models and mounted skeletons from museums, life restorations reproduced from the technical literature, and original art produced for the book, including quite a few line drawings by one L. Sprague De Camp. Roy Krenkel even contributed an original piece, shown above (if you don’t know Krenkel, he was a contemporary and sometime collaborator of Al Williamson and Frank Frazetta, and his art collection Swordsmen and Saurians is stunning and still gettable at not-completely-ruinous prices; I’ve had mine since about 1997).
ANYWAY, as entertaining as The Day of the Dinosaur is, it doesn’t do much to help us regenerate the tale of the regenerated tail. Here’s the entire story, from page 114:
Sauropods, some students think, had great powers of regenerating lost parts. One specimen from Wyoming is thought to have lost the last quarter of its tail and regrown it, along with twenty-one new tail vertebrae. That is better than a modern lizard can do; for the lizard, in regenerating its tail, grows only a stumpy approximation of the original, without new vertebrae.
That’s it. No sources mentioned or cited, so no advance over Wood in terms of tracking down the origin of the story.
Massospondylus tail with traumatic amputation at caudal 25 (Butler et al. 2013: fig. 1A).
To be clear, I don’t really think there is a sauropod that regrew its tail, especially since we have evidence for traumatic tail amputation without regeneration in the basal sauropodomorph Massospondylus (Butler et al. 2013), in the theropod Majungasaurus (Farke and O’Connor 2007), and in a hadrosaur (Tanke and Rothschild 2002). But I would love to learn how such a story got started, what the evidence was, how it was communicated, and most importantly, how it took on a life of its own.
If anyone knows any more about this, I’d be very grateful for any pointers. The comment thread is open.
References
- Butler, R. J., Yates, A. M., Rauhut, O. W., & Foth, C. 2013. A pathological tail in a basal sauropodomorph dinosaur from South Africa: evidence of traumatic amputation? Journal of Vertebrate Paleontology 33(1): 224-228.
- De Camp, L. S., and De Camp, C. C. 1968. The Day of the Dinosaur. Bonanza Books, New York, 319 pp.
- Farke, A. A., & O’Connor, P. M. 2007. Pathology in Majungasaurus crenatissimus (Theropoda: Abelisauridae) from the Late Cretaceous of Madagascar. Journal of Vertebrate Paleontology, 27(S2): 180-184.
- Krenkel, R. G. 1989. Swordsmen and Saurians: From the Mesozoic to Barsoom. Eclipse Books, 152 pp.
- Tanke, D. H., & Rothschild, B. M. 2002. DINOSORES: An annotated bibliography of dinosaur paleopathology and related topics—1838-2001. Bulletin of the New Mexico Museum of Natural History and Science, vol. 20.
- Wood, G. L. 1982. The Guinness Book of Animals Facts & Feats (3rd edition). Guinness Superlatives Ltd., Enfield, Middlesex, 252 pp.
It’s a miracle!
June 30, 2019
I’ll see your face-of-the-blessed-virgin-in-a-waffle and raise you the fourth dorsal vertebra of the Giraffatitan brancai paralectotype BM.R.2181 (formerly HMN S II) in a dandelion leaf:
I saw this lying on the ground as my friend Nataley was playing a short set at a festival, and it immediately made me think of this:
Janensch (1950:Abb. 54). 17ter Präsakralwirbel (SII), Hinteransicht.
Zdeněk Burian at decent resolution
May 30, 2019
Next to Charles Knight, the Czech painter Zdeněk Burian was arguably the most influential and important of the early palaeoartists. His dinosaurs tend to have a stately quality that’s very much at odds with our post-Dinosaur Renaissance sensibilities, but which has its own charm. Here’s arguably his most famous (and incorrect) piece, the snorkelling brachiosaurs:
The reason I mention him now is that I recently stumbled across the Paleo Porch site containing decent-quality images of his artworks. For some reason, Burian’s work always seems to appear in low-quality, small-size scans which do nothing to mitigate his tendency to use muted colours and low contrasts. So it’s nice to see his work looking relatively bold and clear.
Here’s his Brontosaurus, too:
There’s a ton we could criticise about both of these pieces; but we don’t have to do that. Instead, let’s just bask in the sheer dinosaurosity of these classic pieces.
Our presentations are up at the 1st Palaeo Virtual Congress
December 5, 2018
The 1st Palaeontological Virtual Congress is underway now, and will run through December 15. Mike and I have two presentations up:
“What do we mean by the directions ‘cranial’ and ‘caudal’ on a vertebra?” by Mike and me, which consists of a video Mike made presenting a slide show that he put together. The presentation sums up our thinking following the series of vertebral orientation posts here earlier this summer and fall, which are all available here.
“Reconstructing an unusual specimen of Haplocanthosaurus using a blend of physical and digital techniques” by me and a gang of WesternU-based collaborators, including Jessie Atterholt and Thierra Nalley, both of whom you saw in our recent pig-hemisecting adventures. Almost everything I’ve written on this blog about Haplocanthosaurus in 2018 was part of the run-up to this presentation (except, somewhat ironically, the post about pneumaticity), which also includes quite a bit that I haven’t put on the blog yet. So even if you follow SV-POW!, the 1PVC slideshow should have plenty of stuff you haven’t seen yet.
IF you can see it–you have to be a registered 1PVC ‘attendee’ to log in to the site and see the presentations. So probably you are either already registered and this post is old news, or not registered and this post seems useless. Why would I bother telling you about stuff you can’t see?
The answer is that neither Mike or I intend for our work to disappear when 1PVC comes to an end on December 15. Both of us are planning to put our abstracts and slide decks up as PeerJ Preprints, which is our default move for conference presentations these days (e.g., this, this, and this). I believe Mike is also going to post his video to YouTube. So the work will not only live on after the congress is over, it will jump to a much broader audience. We’re looking forward to letting everyone see what we’ve been up to, and I’m sure we’ll have some more things to say here when that happens.
So, er, go see our stuff if you’re a 1PVC attendee, and if you’re not, hang in there, we’ll have that stuff out to you in a few days. UPDATE: The Haplo presentation is up now (link).
In my recent visit to the LACM herpetology collection, I was interested to note that almost every croc, lizard, and snake vertebra I saw had a pair of neurovascular foramina on either side of the centrum, in “pleurocoel” position. You can see these in the baby Tomistoma tail, above. Some vertebrae have a big foramen, some have a small foramen, and some have no visible foramen at all. Somehow I’d never noticed this before.
This is particularly interesting in light of the observation from birds that pneumatic diverticula tend to follow nerves and vessels as they spread through the body. Maybe we find pneumatic features where we do in dinosaurs and pterosaurs because that’s where the blood vessels were going in the babies. Also, these neurovascular foramina in extant reptiles are highly variable in size and often asymmetric – sound familiar?
It should. Caudal pneumaticity in the tail of Giraffatitan MB.R.5000. Dark blue vertebrae are pneumatic on both sides, light blue vertebrae only have fossae on the right side. Wedel and Taylor (2013b: Figure 4).
I am starting to wonder if some of the variability we associate with pneumaticity is just the variability of soft tissue, full stop. Or if pneumaticity is variable because it developmentally follows in the footsteps of the blood vessels, which are themselves inherently variable. That seems like a promising line of inquiry. And also something I should have though of a lot sooner.
