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]
Cervical vertebrae of Suuwassea on display at the Academy of Natural Sciences in Philadelphia
March 20, 2018
I was in Philadelphia and New York last week, visiting colleagues on the East Coast and getting in some collaborative research. Much more to say about that in the future – even just the touristy stuff will fill several posts.
One highlight of the trip was visiting the Academy of Natural Sciences in Philadelphia last Friday. Ted Daeschler (of Tiktaalik fame) and Jason Poole (who illustrated this sweet book) were my generous hosts and I got to see a ton of cool stuff both out on exhibit and behind the scenes. Seriously, I could post for a month just on the Academy visit.
A personal highlight for me was seeing the cervical vertebrae of the sauropod dinosaur Suuwassea on exhibit. They are in a glass case and you can get around them pretty well to see a lot of anatomy. At first I was pumped to get nice color photos of all the vertebrae from up close and from multiple angles. Then I thought, “Huh, maybe I should just shoot a video.” So I did. Here you go, four minutes of hot sauropod vertebra action:
Plateosaurus engelhardti (originally P. trossingensis) SMNS 13200 cervical vertebrae 3-8 in left lateral view. C8 is roughly 15 cm long.
In the recent post on serial variation in sauropod cervicals, I wrote:
Even in ‘adult’ sauropods like the big mounted Apatosaurus and Diplodocus skeletons, the anterior cervicals are less complex than the posterior ones. Compared to posterior cervicals, anterior cervicals tend to have simpler pneumatic fossae and foramina, fewer laminae, and unsplit rather than bifid spines. In all of these things the anterior cervicals are similar to those of juveniles of the same taxa, and to those of adults of more basal taxa. This is also true in prosauropods–in Plateosaurus, the full complement of vertebral laminae is not present until about halfway down the neck.
I was working from memory there and actually understated things a bit. Plateosaurus presacral vertebrae don’t have well-developed spinal laminae, but they do eventually get the four major diapophyseal laminae–the anterior centrodiapophyseal lamina (ACDL), posterior centrodiapophyseal lamina (PCDL), prezygodiapophyseal lamina (PRDL), and postzygodiapophyseal lamina (PODL–please see the lamina tutorial if you need a refresher on these and the other 15 commonly identified laminae). But they aren’t all present halfway down the neck–the ACDL doesn’t really show up until the cervicodorsal transition. The other three kick in sequentially down the neck, as shown in the above image. I think that’s pretty cool, that you get different character states expressed at different points along the neck, in one individual organism, at one time. And possibly also at different times–in sauropods, the anterior cervicals tend to look more ‘juvenile’ or ‘primitive’, even in adult animals, so all of the cervicals go through a juvenile stage, but not all of them grow out of it. I don’t know if there’s a word for that–some kind of serial heterochronotopomorphy or the like–but hopefully someone will enlighten me.
I took the original photo in the collections at the Staatliches Museum für Naturkunde Stuttgart in the spring of 2004. Markus Moser and Rainer Schoch were wonderful hosts during my visit. Mike did all the work of turning the raw photo into a figure, so thanks to him for getting this off my hard drive and out into the world.
Sauropod Vertebra Picture of the Week 