This is SUSA 515, a partial skeleton of Camarasaurus on display in the Museum of Moab. (SUSA stands for Southeastern Utah Society of Arts & Sciences.) It was described by John Foster in 2005.

I like this thing. The neural spines are blown off so you can see right down into the big pneumatic cavities in the dorsal vertebrae. And unlike the plastered, painted, and retouched-to-seeming-perfection mounted skeletons in most museums, this specimen reflects how most sauropod specimens look when they come out of the ground. With a few dorsal centra, a roadkilled sacrum, and some surprisingly interesting caudals, it puts me strongly in mind of MWC 8028, the Snowmass Haplocanthosaurus (another John Foster joint: see Foster and Wedel 2014).

Frankly, it doesn’t look like much: 17 centra and some odd bits of pelvis. Surely, with so many good Camarasaurus specimens in the world, this one couldn’t possibly have anything new to tell us about the anatomy of that genus. And yet, it has a couple of unusual features that make it worthy of attention. My colleagues and I are working on those things right now, and you’ll be hearing more about this specimen in the very near future.



We all know that apatosaurines have big honkin’ cervical ribs (well, most of us know that). But did they also have unusually large neural spines?

The question occurred to me the other day when I was driving home from work. I was thinking about C10 of CM 3018, the holotype of Apatosaurus louisae, and I thought, “Man, that is a lot of neural spine right there.”

Why was I thinking about C10, particularly? I traced and also stacked Gilmore’s (1936) drawing for my 2002 paper with Kent Sanders, and recycled the trace for my 2007 prosauropod paper, and recycled the stack-o-C10s for my 2013 PeerJ paper with Mike. So for better or worse C10 is my mental shorthand for A. louisae, the same way that their respective C8s seem to capture the essence of Giraffatitan and Sauroposeidon.

I decided that the quick-and-dirty solution was to compare the vertebrae of A. louisae with those of Diplodocus carnegii, the default reference diplodocid, and see how they stacked up. With the cotyles scaled to the same vertical diameters, this is what we get for C9 and C10 of CM 3018 (lighter gray, background, traced from Gilmore 1936) vs CM 84/94 (darker gray, foreground, traced from Hatcher 1901):

The A. louisae verts are a hair taller, proportionally, than those of D. carnegii, but not by much. The difference is trivial compared to the differences in centrum length and cervical rib size.

So where did I get this apparently erroneous impression that Apatosaurus had giant neural spines? Maybe it’s not that the neural spines of apatosaurines in particular are so large, but rather than diplodocids of all types have large neural spines compared to non-diplodocids. Here are the same vertebrae compared for D. carnegii (dark gray, background) and Camarasaurus supremus (black, foreground, traced from Osborn and Mook 1921):

I deliberately picked the longest C9 in the AMNH collection, and the least-distorted C10. The first surprise for me was how well this C. supremus C9 hangs with D. carnegii in terms of proportions. That is one looooong Cam vert. In any other sauropod, it would probably be beautiful. But because it’s Camarasaurus it attained its length in the most lumpen possible way, with the diapophysis way up front, the neural spine apex way at the back, and in the middle just…more vertebra. Like a stretch limo made from a Ford Pinto, or Mike’s horrifying BOBA-horse.

Inevitable and entirely justified Cam-bashing aside, it’s striking how much smaller the whole neural arch-and-spine complex is in C. supremus than in D. carnegii. And remember that D. carnegii is itself a bit smaller than Apatosaurus, spine-wise. Is this maybe a diplodocoid-vs-macronarian thing, at least in the Morrison? Here’s the C10 stack with Brachiosaurus included, represented by BYU 12867 (which I think is probably a C10 based on both centrum proportions and neural spine shape – see Wedel et al. 2000b for details), and with labels added because it’s getting a little nuts:

I like this; it shows a lot. Here are some things to note:

  • The diplodocids don’t just have taller neural spines, their pre- and postzygapophyses are also higher than in the macronarians. That’s gotta mean something, right? All else being equal, putting the zygs farther from the intervertebral joints would reduce the flexibility of the neck. Maybe diplodocoids could get away with it because they had more cervicals, or maybe their necks were stiffened for some reason.
  • The zygs being set forward of their respective centrum ends in the macronarians really comes through here.
  • The Brachiosaurus vert isn’t that different from a stretched (and de-uglified) Cam vert, with a slightly higher neural spine to help support the longer neck. (Maybe this is why Cam inspires such visceral revulsion: it reads as a failed brachiosaur.)
  • This emphasizes the outlier status of Apatosaurus in the cervical rib department. It bears repeating: the cervical ribs of Camarasaurus are certainly wide, but they’re not nearly as massive or ventrally expanded as in apatosaurines.

So far, pretty interesting. I’d like to add Barosaurus and Haplocanthosaurus to round out the “big six” Morrison sauropods. I known Haplo has big, tall, almost apatosaurine neural spines (as shown above, with arrows highlighting the epipophyses), but for Baro I’d have to actually do the comparison to see where it falls out.

The idea of bringing in Barosaurus also forces the question, previously glossed over, of how legit it is to compare C10s of all these animals when their cervical counts differed. C. supremus is thought to have had 12 vertebrae in its neck, Brachiosaurus 13 (based on Giraffatitan), A. louisae and D. carnegii 15, and Barosaurus probably 16. It would be more informative to graph neural spine height divided by cotyle diameter along the column for all of these critters, plus Kaatedocus and Galeamopus. But that’s a lot of actual work, and as much fun as it sounds (really, I’d rather be doing that), I have summer teaching to prep for and field gear to wrangle. So I’ll have to revisit this stuff another time.


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.