Apatosaurus, Russian doll edition
December 3, 2007
My favorite room in the world is the big bone room at BYU’s Earth Science Museum. It is the only place on the planet that has good material of all six of the best-known Morrison sauropods: Apatosaurus, Barosaurus, Brachiosaurus, Camarasaurus, Diplodocus, and Haplocanthosaurus. So if you are looking at, say, a middle cervical of Apatosaurus and you think, “Hmm, I wonder how this looks in X,” where X is one of the other five genera listed above, you can just go look. It’s phenomenal.
The big vert here is a posterior cervical of Apatosaurus. Those big loops on the side are formed by the diapophyses and parapophyses (sticking out from the vertebra) and the capitula and tubercula of the cervical ribs. Capitula are rib heads, and they articulate with the parapophyses, which are the lower of the two sets of rib articulations on the vertebral centrum. Tubercula are rib tubercles, and they articulate with the diapophyses, which are at the ends of the massive transverse processes sticking out sideways from the neural arch. Here’s a labeled version, just in case the verbal description made no sense. I know Mike covered this stuff back in Tutorial 2, but Apatosaurus is frankly pretty freaky in the cervical rib department.
You’ll notice that the neural spine is split down the middle, which is the case in many diplodocoids but not all of them. Bifurcated neural spines are also found in Camarasaurus, some titanosaurs, and to a lesser extent in some mamenchisaurs, so the character definitely evolved more than once. More about bifid neural spines another day…
At last, to the point. In front of the big vert you can see a smaller one, about the size of a fist. That’s a vertebral centrum from the same part of the neck from a much smaller individual of Apatosaurus, probably somewhere between horse- and elephant-size. And that’s not all–in front of the scale bar, wrapped up in plastic, is a centrum from a wee little baby Apatosaurus about the size of poodle. Why is the vert in plastic? Because it was going off to the micro-CT scanner at the University of Utah, which is in a cleanroom, so all specimens have to be hermetically sealed. I didn’t think to shoot this little growth series lineup until the vert was already bagged, and I haven’t been back since to set it up again.
Alas, the baby Apatosaurus vert and the CTs of its internal structure will also have to wait for another day. We’re such teases…
Sauropod Vertebra Picture of the Week 
December 4, 2007 at 2:06 pm
“Here’s a labeled version, just in case the verbal description made no sense. I know Mike covered this stuff back in Tutorial 2, but …”
For them of us as are just learning this stuff, the more labeled pictures the better.
“… Apatosaurus is frankly pretty freaky in the cervical rib department.”
That is seriously freaky. Out of context, I’d have no idea what to make of that image. The neural spine looks like a fake fossil bat. Darren could have had some fun with that over in TetZoo, conning us rubes.
BTW, better than the scale bar the wall outlet in the background gives a good idea of scale.
December 5, 2007 at 4:52 am
Nice photo! Sauropod cervicals are some of the most fantastic abstract sculptural shapes I know of. One, mounted with the condyle up, would make a great war memorial… for some futuristic, outer space, war!
On an anatomical, rather than aesthetic side… In the photo the downward-ly projecting spike of the cervical rib is just visible (directed away from the camera, joining the rest at the angle at the bottom between the capitulum and tuberculum. Is there an intimidating Latin name for this spike?
December 8, 2007 at 12:57 am
Hello all,
Since this site is all about sauropod vertebrae, you guys really need to talk about rebbachisaurus’ neural spines! :) As far as I know, virtually nothing is known about them, and they intrigue me, as I am a sauropodo-phile and would really like to draw accurate pictures of sauropods (especially the rebbachisaurids–nigersaurus notwithstanding). Enough of this piddly apatosaurus stuff! ;)
December 8, 2007 at 3:36 pm
Hi, Zach. Yes, it would be great to do rebbachisaur vertebrae. Unfortunately, rebbachisaur material is not readily accessible — at least to Darren and me, who live in England. The only putative British material known to me is teeth from the Wealden (see the 2005 Nigersaurus paper) … unless of course Xeno turns out to be derived rebbachisaur. The type material of Rebbachisaurus garasbae is at the museum in Paris, but I’ve not been able to get over there for a while, and the last time I was there I somehow managed to miss even the single dorsal in the public gallery. So we really have nothing to show you that’s not in the published literature.
So right now, the place to go if you want to see rebbachisaur dorsals is the recent Sereno et al. paper in PLoS One, at http://www.plosone.org/article/info:doi%2F10.1371%2Fjournal.pone.0001230
This is is a fantastic journal for several reasons. First, of course, it’s freely available to everyone who cares about science — not just to university libraries that pay a subscription. And second, it put the figures up on the web in extremely high resolution: as Exhibit A, I offer fig. 3 from the Sereno et al. paper, at
http://www.plosone.org/article/fetchObject.action?uri=info%3Adoi%2F10.1371%2Fjournal.pone.0001230.g003&representation=PNG_L
This is 3537×2571 pixels, enough that even individual elements like the figured cervical and dorsal are visible in some detail.
And now a brief, tangential rant: the best palaeo journal in the world SHOULD be Palaeontologia Electronica at http://palaeo-electronica.org/ which, like PLoS One is freely available to anyone with an Internet connection and which, unlike PLoS One, includes detailed studies as well as the super-short “extended abstract” papers that ou find in Science and Nature. Unfortunately, unlike PLoS One, its figures are available only in very poor resolutions that are near to useless for comparative anatomical purposes. As Exhibit B, I offer you Fig. 12 of Pete Rose’s description of Paluxysaurus:
http://palaeo-electronica.org/2007_2/00063/fig_12.htm
If only PE would publish its figures in the same high resolution that it demands its authors submit them, it would be ten times as useful. Bah.
December 8, 2007 at 8:12 pm
Even for someone who doesn’t rise to the level of amateur or dilletante but mere gawper at science as I am, the PE stuff sucks compared to the PLOS pic (which is gorgeous). Even I can see the PE image would be virtually worthless to any professional. You’d need to e-mail the author and get him to send you the hi-res image to make anything of it and I’m sure there are too few paleontologists with too little time to waste requesting and sending images like that. Server space isn’t expensive enough there is any excuse for not using hi-res images, especially if you have pretensions to being a professional journal. You wonder what on earth they’re thinking.
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