The most complete caudal vertebra of the Snowmass Haplocanthosaurus (Foster and Wedel 2014) in right lateral view: specimen photo, CT scout, 3D model, 3D print at 50% scale. The photos of the specimen and the 3D print probably match the worst with the others, because they are subject to perspective distortions that the digital reconstructions are free from.

Here’s one nice thing about having a 3D print of a specimen that you’re working on: you can hand it to other anatomists and paleontologists and get their take on its weird features, and it’s small enough and light enough that you can bring it halfway across the country to show in person to an entirely different set of colleagues. For all that we hear about humans being a visual species, we are also a tactile one, and in my admittedly limited experience, grokking morphology by handling 3D printed fossils is almost as good as – and for big, heavy, fragile sauropod vertebrae, sometimes better than – handling the real thing.

Many thanks to Julia McHugh at Dinosaur Journey for access to the specimen, John Yasmer at the Hemet Valley Medical Center for CT scanning, Thierra Nalley at Western University of Health Sciences for help with segmenting and visualization in Amira, and Gary Wisser, WesternU’s 3D visualization specialist, for the sweet print. Further bulletins as events warrant.


Foster, J.R., and Wedel, M.J. 2014. Haplocanthosaurus (Saurischia: Sauropoda) from the lower Morrison Formation (Upper Jurassic) near Snowmass, Colorado. Volumina Jurassica 12(2): 197–210. DOI: 10.5604/17313708 .1130144


Remember this broken Giraffatitan dorsal vertebra, which Janensch figured in 1950?

It is not only cracked in half, anteroposteriorly, it’s also unfused.

Here’s a better view of the broken face, more clearly showing that the neural canal is (a) much taller than wide – unlike all vertebrate spinal cords – and (b) almost entirely situated ventral to the neurocentral joint, getting close to the condition in the perverted Camarasaurus figured by Marsh.

Here’s a dorsal view, anterior to the top, with Mike’s distal forelimbs for scale.

Left lateral view.

Right lateral view – note the subtle asymmetries in the pneumatic foramen/camera. A little of that might be taphonomic distortion but I think much of it is real (and expected, most pneumatic systems produce asymmetries).

And postero-dorsal view, really showing the weird neural canal to good advantage. In this photo and in the pure dorsal view, you can see that the two platforms for the “neural arch” – which, as in the aforementioned Camarasaurus, is neither neural nor an arch – converge so closely as to leave only a paper-thin gap.

A few points arise. As explained in this post, it makes more sense to talk about the neurocentral joint migrating up or down relative to the neural canal, which is right where it always is, just dorsal to the articular faces of the centrum.

So far, in verts I’ve seen with “offset” neurocentral joints, the joint tends to migrate dorsally in dorsal vertebrae, putting the canal inside the developmental domain of the centrum (which now includes a partial or total arch in an architectural sense, even though the chunk of bone we normally call the neural arch develops as a separate bit) – as shown in the first post in this series. In sacral and caudal vertebrae, the situation is usually reversed, with the joint shifted down into what would normally be the centrum, and the canal then mostly or completely surrounded by the arch – as shown in the second post in the series. This post then doesn’t really add any new concepts, just a new example.

Crucially, we can only study this in the vertebrae of juveniles and subadults, because once the neurocentral joints are fused and remodeled, we usually can’t tell where the old joint surface was. So it’s like cervicodorsal and caudal dorsal pneumatic hiatuses, in that the feature of interest only exists for part of the ontogeny of the animal, and our sample size is therefore inherently limited. Not necessarily limited by material – most museums I’ve visited have a fair amount of juvenile and subadult material in the collections – but limited in published visibility, in that for many sauropods only the largest and most complete specimens have been monographically described.

So once again, the answer is simply to visit collections, look at lots of fossils, and stay alert for weird stuff – happily, a route that is open to everyone with a legitimate research interest.


  • Janensch, W. 1950. Die Wirbelsaule von Brachiosaurus brancai. Palaeontographica (Suppl. 7) 3:27-93.

I have used this photo in loads of talks, but as far as I can tell, this is the first time I’ve put it up on SV-POW! (I am certain that, having said that, someone will find a previous instance – if so, consider this an extremely inefficient and lazy form of search.) The vert is OMNH 1670, the most complete and nicest dorsal of the giant Oklahoma apatosaurine, probably a D5 or D6. That’s me back in 2004. Photo by my then fellow grad student in the Padian lab, Andrew Lee. I’m 6’2″ and have normally-proportioned human arms, but if you’re trying to figure out the scale, that vert is 135cm tall, with an anterior centrum face 38cm tall by 46cm wide (partly reconstructed but probably accurate). See this post for more details and a fairly exhaustive list of measurements.

Here’s a stupid thing: roughly 2-3 times a year I go to the field or to a museum and get hundreds of SV-POW!-able photos. Then I get back to the world and catch up on all of the work that piled up while I was away. And by the time I’m done with that, whatever motivating spark I had – to get some of those photos posted and talk about the exciting things I figured out – has dissipated.

Case in point – this bitchin’ shark, prepped in ventral view, which I saw last month in the natural history museum in Vienna. Look at that fat, muscular tail – this shark is swole.

That’s dumb. And this blog is in danger of slipping into senescence, and irrelevance.

So here’s my New Year blog resolution for 2018: I’m getting us back to our roots. I, or we – I am taking this plunge without consulting with Mike (surprise, buddy!) – will post a new, never-posted-before photo, at least once a week, for the whole year. It may not always be a sauropod vertebra, but if often will be, because that’s what I have the most of, and the most to yap about. And I will try to write something interesting about each photo, without lapsing into the logorrhea that has too often made this blog too exhausting to contemplate (at least from this side of the keyboard).

Wish me luck!


August 15, 2017

Here is a fascinating sequence of five consecutive posterior dorsal vertebra — AMNH FARB 291 from the”Big Bone Room” at the AMNH:

AMNH FARB 291, five consecutive posterior dorsal vertebrae of a probably brachiosaurid sauropod, in right lateral view. The vertebrae are embedded in a plaster block, which has been desaturated in this image.

Matt and I first saw this specimen back in February 2009, when we were mostly there to look at Apatosarusminimus (and then again in 2012). As soon as our eyes lit on it, we couldn’t help but be captivated by its bizarre biconcave centra. We immediately started flippantly referring to it as “Biconcavoposeidon” — the ugliest name we could come up with — and in our subsequent discussions the name has stuck (often abbreviated to “BCP”).

  • Taxonomic note: for avoidance of doubt, “Biconcavoposeidon” is not and will never be a formal taxonomic name, only an informal specimen nickname. If at some future point we conclude that this specimen represents a new taxon, and name it, we will definitely not use the name “Biconcavoposeidon”. If you ever use the name, please do not set it in italics.

As you can see in this front view, the specimen is sheared: the upper part of the vertebrae have been displaced to their left (which is the right as we see it in this image):

AMNH FARB 291, most anterior of five consecutive posterior dorsal vertebrae of a probably brachiosaurid sauropod, in anterior view.

Apart from the shearing, though, and the truncation of the neural spines shortly above the transverse processes, the specimen is in pretty good nick. Crucially, it’s not been “restored” in plaster to conceal what is and is not real bone — unlike many specimens of that era. It came out of the Bone Cabin quarry in 1898, back when scientific information was routinely discarded in order to obtain a more beautiful-looking specimen.

This is the specimen that I’ll be presenting at SVPCA this year — though only as a poster, unfortunately: there’s no talk for me, Matt or Darren this year. We’ve posted our abstract (including the illustration above) to the nascent PeerJ collection for SVPCA 2017, and we’re looking forward to seeing more of the materials from that conference — abstracts, then manuscripts, then papers — appearing in the collection.

So far as we know, there’s no other sauropod specimen with biconcave posterior dorsal vertebrae. (And, no, Amphicoelias is not an exception, despite its name.) But have we missed any?

Wouldn’t it be great if there was a database of all dinosaur specimens?

Well, there is — or at least, it’s on its way. Gunnar Bivens, who we know from SV-POW! comments as bricksmashtv, in creaing a vast Google-Docs Spreadsheet which at the time of writing has the following entries in various tabs:

  • 1446 sauropods (Yay!)
  • 50 theropods
  • 2 thyreophorans (Hey, you gotta start somewhere.)
  • 3 ornithopods
  • 25 marginocephalians

Other tabs yet to be populated: basal dinosaurs, basal sauropodomorphs, basal ornithoscelidans, basal ornithischians.

(I think it’s a mistake to leap at the Baron et al. 2017 Ornithoscelida hypothesis, abandoning so precipitately the well-established Saurischia/Ornithischia division, but that’s how things stand.)

You can help

The spreadsheet is set up so that anyone can leave comments. Gunnar has done lots of work to get it going, essentially just by reading a ton of papers and entering all the details of dinosaur specimens — but no one person can possibly cover the whole literature.

Here’s what I think is the most efficient way to contribute: if you set up a Google Docs spreadsheet of your own, with the columns in the same order as Gunnar’s, then you can enter a bunch of specimens. When you’re ready, leave a comment on the relevant tab of the master spreadsheet pointing to your additions, and Gunnar can copy-paste them in.

Here is the link to the spreadsheet again. Get building!


  • Baron, Matthew G., David B. Norman and Paul M. Barrett. 2017. A new hypothesis of dinosaur relationships and early dinosaur evolution. Nature 543:501–506. doi:10.1038/nature21700

Anterior view. Dorsal is to the upper right. The neural spine and left transverse process are missing.

Here’s a closeup of the condyle. The outer layer of cortical bone is gone, allowing a glimpse of the pneumatic chambers inside the vert. The erosion of the condyle was probably inflicted post-excavation by relatively unskilled WPA workers, whose prep tools were limited to chisels, penknives, and sandpaper. Because the bones from the Kenton localities are roughly the same color as the matrix, the preparators sometimes did not realize that they were sanding into the bones until the internal structure was revealed. Bad for the completeness of this specimen, but good for pneumaticity junkies like me, because this baby is too big to be scanned by any but the largest industrial CT machines.

For other posts on the giant Oklahoma apatosaur, see:

I choose Haplocanthosaurus

November 18, 2016


Oh man, 2016, you are really working on my nerves.

Sometimes it’s a positive balm to hold a piece of an animal dead and gone for 145 million years, or stare at a thousand vertical feet of sandstone, and know that we are all ants.

These lovelies here intrigue me deeply. They’re three of the caudal vertebrae recovered from the Snowmass Haplocanthosaurus that John Foster and I described a couple of years ago. Pretty sure I’ll have more to say about them in the future. For now it’s enough that they’ve come across such a vast gulf of time and given this stressed-out primate a little perspective.


Foster, J.R., and Wedel, M.J. 2014. Haplocanthosaurus (Saurischia: Sauropoda) from the lower Morrison Formation (Upper Jurassic) near Snowmass, Colorado. Volumina Jurassica 12(2): 197–210. DOI: 10.5604/17313708 .1130144