Back in the spring of 1998, Kent Sanders and I started CT scanning sauropod vertebrae. We started just to get a baseline for the Sauroposeidon project, but in time the data we collected formed the basis for my MS thesis, and for a good chunk of my dissertation as well. Mostly what we had available to scan was Morrison material. Between imperfect preservation, inexpert prep (by WPA guys back in the ’30s), and several moves over the decades, most of the verts from the Oklahoma Morrison have their neural spines and cervical ribs broken off. One of the first things I had to figure out was how to tell broken vertebrae of Camarasaurus from those of Apatosaurus (at the time; Brontosaurus is back in contention now). Here’s a thing I made up to help me sort out cervical centra of Camarasaurus and whatever the Oklahoma apatosaurine turns out to be. It’s a recent production, but it embodies stuff from my notebooks from 20 years ago. Should be useful for other times and places in the Morrison as well, given the broad spatiotemporal overlap of Camarasaurus and the various apatosaurines.

For a related thing in the same vein, see Tutorial 30: how to identify Morrison sauropod cervicals.

More elephant seals soon, I promise.

UPDATE 20 Feb 2018

Ken Carpenter sent this by email, with a request that I post it as a comment. Since it includes an image, I’m appending to the post, because it makes an important point that I neglected to mention.

Camar post cerv

Ken: Sorry, Matt. Not so easy. The last cervical of Camarasaurus from the Cleveland Lloyd Quarry is more apatosaurine-like than Camarasaurus-like based on your posting. Note the position of both zygapohyses with both ends of the centrum.

My response: Yes, good catch. I meant to say in the post that my distinguishing characters break down at the cervico-dorsal transition. Even so, in this Cleveland Lloyd vert the postzyg is still forward of a line drawn directly up from the cotyle. I’ve never seen that in an apatosaurine–going into the dorsal series, the postzygs tend to be centered over a line projected up from the rim of the cotyle. (If anyone knows of counterexamples, speak up!)

For distinguishing cervico-dorsals, apatosaurines tend to have much taller neural spines than Camarasaurus, and this carries on through the rest of the dorsal series. In apatosaurine dorsals, the height of the spine above the transverse processes always equals or exceeds the height of the arch below the transverse processes. In Camarasaurus, the height of the dorsal neural spines is always less than or equal to the height of the arch. The shapes of the spines are fairly different, too. Maybe that will be the subject of a future post.


In the first installment in this series (link), we looked at a couple of weird sauropod vertebrae with neurocentral joints that were situated either entirely dorsal or ventral to the neural canals. This post has more examples of what I am calling “offset” neurocentral synchondroses.

I decided it made more sense to refer to the synchondrosis as being offset, instead of referring to the neural canal as offset. Because the neural canal in all of these vertebrae is right where it pretty much always is, just dorsal to the articular surfaces of the centrum. In an adult, fused vertebra, there’d be no sign that anything unusual had ever happened. So I think it makes more sense to talk about the neurocentral joint having migrated dorsally or ventrally relative to the canal, rather than vice versa. If you know differently, or if these weirdos have been addressed before elsewhere and I’ve just missed it, please let me know in the comments!

Here’s a plate from Marsh (1896) showing caudal vertebrae of Camarasaurus (“Morosaurus” in O.C. Marsh parlance), which echo the Alamosaurus caudal from the first post in having the neurocentral joint almost entirely ventral to the neural canal. The neural arch here doesn’t just arch over the canal dorsally, it also cuts under it ventrally, at least in part.

This plate is also nice because it shows the relationships among the arch, centrum, and caudal ribs before they fuse. Here’s the caption, from Marsh (1896):

Here’s the preceding plate, Plate 33, with illustrations of an unfused Camarasaurus sacrum.

And its caption:

This plate not only shows how the sacral ribs fuse to the arch and spine medially, and to each other laterally (forming the sacrocostal yoke), it also shows a last sacral that is very similar to the aforementioned caudals in the position of the neurocentral joint. But interestingly that neurocentral joint offset only seems to be present in the last caudal sacral – the lower figure shows widely-separated neurocentral joint surfaces in the more anterior centra, indicating that the neural arches (not figured in this dorsal view) did not wrap around the neural canal to approach the midline. (I think we’re looking at S2 through S5 here, and missing a dorso-sacral.)

So now I’m freaked out, wondering if this neural arch wrap-around in the caudals is common to most sauropods and I just haven’t looked at enough juvenile caudals to have spotted it before. As always, feel free to ablate my ignorance in the comments, particularly if you know of more published examples. I’m a collector.

The neural canal of that last sacral also has a very interesting cross-sectional shape, like a numeral 8. I have some thoughts on that, but they’ll keep for a future post in this series.

Hey, look, a new sauropod vertebra to kick off the new year!

I’ve blogged a lot about the giant – and tiny – apatosaurines from the Morrison Formation of Oklahoma, and just once on Saurophaganax. But otherwise I don’t think I’ve covered any of the other Oklahoma Morrison dinos. So here’s a start: a pretty decent Camarasaurus dorsal. Broken transverse processes traced from Osborn and Mook (1921). Like all of the Oklahoma Morrison dinos, it’s from the quarries on or near Black Mesa, at the far northwestern corner of the Oklahoma panhandle.

Based on the narrowness of the neural arch and spine, I don’t think this vert can be any farther forward than D6 – anterior Cam dorsals are w-i-d-e. It would be odd for a camarasaur to have a spine split that deeply as far back as D10 or D11 (see Wedel and Taylor 2013). The centrum is very anteriorposteriorly short, which is a posterior dorsal character, but based on Osborn and Mook (1921) the centra can be this short as far forward as D6. So on the balance of the evidence, I think it’s probably a D6 or D7. But that is just an estimate, which might be off by a couple of positions either way.

Tons more that could be said about this specimen, but I’m going to play against type and not write a dissertation for a change. So, here’s OMNH 1811. We’ll probably come back to it at some point.



Here’s a bunch of cool stuff that is either available now or happening soon:

Sauropod Dinosaurs book excerpt in Prehistoric Times

Been on the fence about the sauropod book Mark Hallett and I wrote? Now you can try before you buy – our chapter on titanosaurs is reprinted in the new issue of Prehistoric Times magazine. I know it’s on newsstands because I picked it up at the local Barnes & Noble yesterday. You can also buy the issue from the PT website, physically or in digital form, solo or as part of a subscription. Many thanks to PT editor and publisher Mike Fredericks for the visibility, the staff at Johns Hopkins University Press for permission, and most of all to Mark Hallett for making it happen. We hope you enjoy it.

Get more sauropods in Mark Hallett’s 2018 dinosaur calendar

Mark has a dinosaur calendar out from Pomegranate, and I’m happy to say that sauropods are featured 5 out of 12 months. The calendar has a nice mix of Hallett classics and some newer works, including the cover art from our book, as shown above. Get it direct from Pomegranate or from Amazon.

Vicki’s public talk on forensic anthropology in December

My better half, anthropologist and author Vicki Wedel, is giving a public talk about her work on the evening of Thursday, December 14, at the Western Science Center in Hemet, California. Her title will be, “Bones, ballistics, and blunt force trauma.” I assume the talk will start at 6:00, but check the WSC website for details. The painted skull above is from the natural history museum in Vienna, and it doesn’t have any connection to the talk other than Vicki thought it was rad and I needed a skull to illustrate the post. For more on Vicki and her work, see these posts: cold case, book.


UPDATE: Final details on Vicki’s talk are out. It will start at 6:00, she’ll be signing copies of her book, Broken Bones: Anthropological Analysis of Blunt Force Trauma, and admission is $5.

My public talk on sauropods and whales in January

In January it will be my turn to give a talk at the Western Science Center. I’m on for the evening of Thursday, January 18. Title is not quite finalized but it will probably something along the lines of, “Dinosaurs versus whales: what is the largest animal of all time, and how do we know?” That’s me with the gray whale skeleton at Long Marine Lab in Santa Cruz, back in 2006. I was helping Nick Pyenson measure whales, back when we were both grad students. Ancient blog posts about that here: gray, blue.

See me in Seattle at Norwescon over Easter weekend

If you want to see me star-struck, come to Norwescon, home of the Philip K. Dick Award, next spring, where I’ll be rubbing shoulders with some vastly more famous people. Hugo, Nebula, and World Fantasy Award winner Ken Liu will be the Writer Guest of Honor, legendary SF&F visionary Wayne Douglas Barlowe Hugo- and World Fantasy Award-winning artist Galen Dara will be the Artist Guest of Honor, Green Ronin is the Spotlight Publisher, and, er, I will be the Science Guest of Honor. Yes, I’m alert to both the honor and the incongruity of the thing. When I’m not Freaking. Out. about hanging with two of my favorite creators, I’ll probably be giving talks on dinosaurs and astronomy (my other thing) and participating on some panels and signing books. I’ll try not to disappoint.

Here’s a dorsal vertebra of Camarasaurus in anterior view (from Ostrom & McIntosh 1966, modified by Wilson & Sereno 1998). It is one of the most disturbing things I have ever seen in a sauropod. It makes my skin crawl.

Here’s why: the centrum and the thing we habitually call the ‘neural arch’ aren’t fully fused, and as this modified version makes clear, the ‘neural arch’ is neither neural nor an arch. Instead of being bounded ventrally by the centrum and dorsally and laterally by the neural arch, the neural canal lies entirely below the synchondrosis between the not-really-an-arch and the centrum.

Why?! WHY WOULD YOU DO THAT, CAMARASAURUS? This is not ‘Nam. This is basic vertebral architecture. There are rules.

Look at c6 of Apatosaurus CM 555 here, behaving as all good vertebrae ought to. Neural arch be archin’, as the kids say.

And if you are seeking solace in the thought that maybe the artist just drew that Cam dorsal incorrectly, forget it. I’ve been to Yale and examined the original specimen. I’ve seen things, man!

Camarasaurus isn’t the only pervert around here. Check this out:

Unfused neural arch of a caudal vertebra of a juvenile Alamosaurus from Big Bend. And I mean, this is a neural arch. This may be the most neural of all neural arches, in that it contains the entire neural canal. It’s more of a neural…ring, I guess. That’s right, this Alamosaurus caudal is batting for the opposite team from the Cam dorsal above. And it’s a team that neither you nor I play on, because we have well-behaved normal-ass vertebrae with neural arches that actually arch, and then stop, like God and Richard Owen intended.

Scientifically, my question about these vertebrae is: well, that is, I mean to say, what!? I think they have damaged me in some fundamental way.

If you have anything more intelligent to add (or even less intelligent – consider the gauntlet thrown down!), the comment thread is open.


  • Ostrom, John H., and John S. McIntosh. 1966. Marsh’s Dinosaurs. Yale University Press, New Haven and London. 388 pages including 65 absurdly beautiful plates.
  • Wilson, J. A. and Paul C. Sereno. 1998. Early evolution and higher-level phylogeny of sauropod dinosaurs. Society of Vertebrate Paleontology, Memoir 5: 1-68.

Step 1: Include the Share-Alike provision in your Creative Commons license, as in the mysteriously popular CC BY-SA and CC BY-NC-SA.

Step 2: Listen to the crickets. You’re done. Congratulations! No-one will ever use your silhouette in a scientific paper, and they probably won’t use your stuff in talks or posters either. Luxuriate in your obscurity and wasted effort.

Pachyrhinosaurus canadensis by Andrew A. Farke, CC BY 3.0, courtesy of


PhyloPic is the incredibly useful thing that Mike Keesey made where makers upload silhouettes of organisms and then people can use them in papers, posters, talks, on t-shirts, bumper stickers, and so on.

At least, they can if the image license allows it. And tons of them don’t, because people include the stupid Non-Commercial (NC) and even stupider Share-Alike (SA) provisions in their image licenses. (Need a refresher on what those are? See the tutorial on licenses.)

Why are these things dumb? Well, you could make a case for NC, but it will still probably kill most potential uses of your images. Most journals are run by companies — well, most are run by incredibly rapacious corporations that extract insane profits from the collective suckerhood that is academia — and using such an image in a for-profit journal would break the Non-Commercial clause. Even open-access journals are a bit murky.

But Share-Alike is way, way worse. What it means is that any derivative works that use material released under CC-BY-SA have to be released under that license as well. Share-Alike came to us from the world of software, where it actually has some important uses, which Mike will expand upon in the next post. But when it comes to PhyloPic or pretty much any other quasi-academic arena, including the Share-Alike provision is misguided.

As of this writing, PhyloPic has two silhouettes of Panphagia. I can actually show you this one, because it doesn’t have the Share-Alike license attached. The other one is inaccessible. Image by Ricardo N. Martinez and Oscar A. Alcober, CC BY 3.0, courtesy of

Why not Share-Alike?

Why is Share-Alike so dumb for PhyloPic? It’s a viral license that in this context accomplishes nothing for the creator. Because the downstream material must also be CC BY-SA (minimally, or CC BY-NC-SA), almost any conceivable use is prevented:

  • People can’t use the images in barrier-based journals, because they’re copyrighted.
  • People can’t use the images in almost all OA journals, because they’re CC BY, and authors can’t just impose a more restrictive license on them willy-nilly.
  • People can’t use the images in their talks or posters, unless they want to make their talks and posters CC BY-SA. Even people who do release their talks and posters out into the wild are probably going to use CC BY if they use anything; they care about being cited, not about forcing downstream users to adopt a pointlessly restrictive license.
  • People probably can’t use the images on t-shirts or bumper stickers; at least, I have a hard time imagining how a physical object could meet the terms of CC BY-SA, unless it’s being given away for free. And even if one could, most downstream creators probably won’t want the headache — they’ll grab a similar image released under a less restrictive license and move on.
  • I can’t even blog the CC BY-SA images because everything we put on this blog is CC BY (except where noted by a handful of more restrictive museum image use policies), and it would more than a little ironic to make this one post CC BY-SA, which it would have to be if it included CC BY-SA images.

You may think I’m exaggerating the problem. I’m not. If you look at the Aquilops paper (Farke et al. 2014), you’ll see a lot of ceratopsian silhouettes drawn by Andy Farke. We were making progress on the paper and when it came time to finish the illustrations, most of the silhouettes we needed had the Share-Alike provision, which made them useless to us. So Andy drew his own. And while he was doing that, I took some of my old sauropod drawings and converted them to silhouettes and uploaded them. Both of us used CC BY, because all we care about is getting cited. And now people are using — and citing! — Andy’s and my drawings in preference to others, some arguably better (at least for the sauropods), that have pointlessly restrictive licenses.

So we have this ridiculous situation where a ton of great images on PhyloPic are essentially unusable, because people put them up under a license that sounds cool but actually either outright blocks or at least has a chilling effect on almost any conceivable use.

Is this a good silhouette of Camarasaurus? Maybe, maybe not. But that’s beside the point: this is currently the only silhouette of Camarasaurus on PhyloPic that you can actually use. By Mathew Wedel, CC BY 3.0, courtesy of

What I do about this

Here’s my take: I care about one thing and one thing only, which is credit. All I need is CC BY. If someone wants to take my stuff and put it in a product and charge a profit, I say go for it — because legally every copy of that product has to have my name on it somewhere, credited as the creator of the image. I may not be making any money off that product, but I’m at least getting exposure. If I go CC BY-NC, then I also don’t get any money, and now I don’t even get that exposure. Why would I hack my own foot off like that? And I don’t use CC BY-SA because I don’t write software, so it has only downsides to offer me.

Now, there are certainly artists in the world with sufficient talent to sell t-shirts and prints. But even for them I’m skeptical that CC BY-NC has much to offer for their PhyloPic silhouettes. I know we’re all nuts around here for monochrome filled outlines of dead animals, but let’s be real, they’re a niche market at best for clothing and lifestyle goods. Personally I’d rather get the citations than prevent someone in Birmingham or Bangkok from selling cladogram t-shirts with tiny copies of my drawings, and I think that would still be true even if I was a professional artist.

What you should do about this

I suspect that a lot of people reading this post are dinosaur enthusiasts. If you are, and you’d like to get your name into published scientific work (whether you pursue writing and publishing yourself or not), get drawin’, and upload those babies using CC-BY. Make sure it is your own original work, not just a skin thrown over someone else’s skeletal recon, and don’t spam PhyloPic with garbage. But if you can execute a technical drawing of a critter, there’s a good chance it will be used and cited. Not only because there are still holes in PhyloPic’s coverage, but because so many otherwise great images on PhyloPic are locked up behind restrictive licenses. To pick an example nearly at random, PhyloPic has two silhouettes of Pentaceratops, and both of them are useless because of the Share-Alike provision in their licenses. You have an opportunity here. Don’t tarry.

If you already uploaded stuff to PhyloPic using CC BY-SA for whatever reason (it sounded cool, Joe Chill murdered your folks, you didn’t realize that it was academic reuse equivalent of radioactive syphilis), change it or replace it. Because all it is doing right now is driving PhyloPic users to other people’s work. Really, honestly, all you are doing is wasting your time by uploading this stuff, and wasting the time of PhyloPic users who have to hover over your pictures to find out that they’re inaccessible.

You don’t get any credit if no-one ever uses your stuff. Or, more precisely, you get 100% of a pie that doesn’t exist. That’s dumb. Stop doing it.


Farke, A.A., Maxwell, W.D., Cifelli, R.L., and Wedel, M.J. 2014. A ceratopsian dinosaur from the Lower Cretaceous of Western North America, and the biogeography of Neoceratopsia. PLoS ONE 9(12): e112055. doi:10.1371/journal.pone.0112055


Fig. 14. Vertebrae of Pleurocoelus and other juvenile sauropods. in right lateral view. A-C. Cervical vertebrae. A. Pleurocoelus nanus (USNM 5678, redrawn fromLull1911b: pl. 15). B. Apatosaurus sp. (OMNH 1251, redrawn from Carpenter &McIntosh 1994: fig. 17.1). C. Camarasaurus sp. (CM 578, redrawn from Carpenter & McIntosh 1994: fig. 17.1). D-G. Dorsal vertebrae. D. Pleurocoelus nanus (USNM 4968, re- drawn from Lull 1911b: pl. 15). E. Eucamerotus foxi (BMNH R2524, redrawn from Blows 1995: fig. 2). F. Dorsal vertebra referred to Pleurocoelus sp. (UMNH VP900, redrawn from DeCourten 1991: fig. 6). G. Apatosaurus sp. (OMNH 1217, redrawn from Carpenter & McIntosh 1994: fig. 17.2). H-I. Sacral vertebrae. H. Pleurocoelus nanus (USNM 4946, redrawn from Lull 1911b: pl. 15). I. Camarasaurus sp. (CM 578, redrawn from Carpenter & McIntosh 1994: fig. 17.2). In general, vertebrae of juvenile sauropods are characterized by large pneumatic fossae, so this feature is not autapomorphic for Pleurocoelus and is not diagnostic at the genus, or even family, level. Scale bars are 10 cm. (Wedel et al. 2000b: fig. 14)

The question of whether sauropod cervicals got longer through ontogeny came up in the comment thread on Mike’s “How horrifying was the neck of Barosaurus?” post, and rather than bury this as a comment, I’m promoting it to a post of its own.

The short answer is, yeah, in most sauropods, and maybe all, the cervical vertebrae did lengthen over ontogeny. This is obvious from looking at the vertebrae of very young (dog-sized) sauropods and comparing them to those of adults. If you want it quantified for two well-known taxa, fortunately that work was published 16 years ago – I ran the numbers for Apatosaurus and Camarasaurus to see if it was plausible for Sauroposeidon to be synonymous with Pleurocoelus, which was a real concern back in the late ’90s (the answer is a resounding ‘no’). From Wedel et al. (2000b: pp. 368-369):

Despite the inadequacies of the type material of Pleurocoelus, and the uncertainties involved with referred material, the genus can be distinguished from Brachiosaurus and Sauroposeidon, even considering ontogenetic variation. The cervical vertebrae of Pleurocoelus are uniformly short, with a maximum EI of only 2.4 in all of the Arundel material (Table 4). For a juvenile cervical of these proportions to develop into an elongate cervical comparable to those of Sauroposeidon, the length of the centrum would have to increase by more than 100% relative to its diameter. Comparisons to taxa whose ontogenetic development can be estimated suggest much more modest increases in length.

Carpenter & McIntosh (1994) described cervical vertebrae from juvenile individuals of Apatosaurus and Camarasaurus. Measurements and proportions of cervical vertebrae from adults and juveniles of each genus are given in Table 4. The vertebrae from juvenile specimens of Apatosaurus have an average EI 2.0. Vertebrae from adult specimens of Apatosaurus excelsus and A. louisae show an average EI of 2.7, with an upper limit of 3.3. If the juvenile vertebrae are typical for Apatosaurus, they suggest that Apatosaurus vertebrae lengthened by 35 to 65% relative to centrum diameter in the course of development.

The vertebrae from juvenile specimens of Camarasaurus have an average EI of 1.8 and a maximum of 2.3. The relatively long-necked Camarasaurus lewisi is represented by a single skeleton, whereas the shorter-necked C. grandis, C. lentus, and C. supremus are each represented by several specimens (McIntosh, Miller, et al. 1996), and it is likely that the juvenile individuals of Camarasaurus belong to one of the latter species. In AMNH 5761, referred to C. supremus, the average EI of the cervical vertebrae is 2.4, with a maximum of 3.5. These ratios represent an increase in length relative to diameter of 30 to 50% over the juvenile Camarasaurus.

If the ontogenetic changes in EI observed in Apatosaurus and Camarasaurus are typical for sauropods, then it is very unlikely that Pleurocoelus could have achieved the distinctive vertebral proportions of either Brachiosaurus or Sauroposeidon.


C6 of Apatosaurus CM 555 – despite having an unfused neural arch and cervical ribs, the centrum proportions are about the same as in an adult.

A few things about this:

  1. From what I’ve seen, the elongation of the individual vertebrae over ontogeny seems to be complete by the time sauropods are 1/2 to 2/3 of adult size. I get this from looking at mid-sized subadults like CM 555 and the hordes of similar individuals at BYU, the Museum of Western Colorado, and other places. So to get to the question posed in the comment thread on Mike’s giant Baro post – from what I’ve seen (anecdata), a giant, Supersaurus-class Barosaurus would not necessarily have a proportionally longer neck than AMNH 6341. It might have a proportionally longer neck, I just haven’t seen anything yet that strongly suggests that. More work needed.
  2. Juvenile sauropod cervicals are not only shorter than those of adults, they also have less complex pneumatic morphology. That was the point of the figure at the top of the post. But that very simple generalization is about all we know so far – this is an area that could use a LOT more work.
  3. I’ve complained before about papers mostly being remember for one thing, even if they say many things. This is the canonical example – no-one ever seems to remember the vertebrae-elongating-over-ontogeny stuff from Wedel et al. (2000b). Maybe that’s an argument for breaking up long, kitchen-sink papers into two or more separate publications?


Wedel, M.J., Cifelli, R.L., and Sanders, R.K. 2000b. Osteology, paleobiology, and relationships of the sauropod dinosaur Sauroposeidon. Acta Palaeontologica Polonica 45:343-388.