There’s almost nothing but nothing there, Brachiosaurus edition
September 3, 2008
You know, we have not done what we intended with this blog. We intended to post pretty pictures of sauropod vertebrae, sketch a few lines of text a la our inspiration, and call it good. But not one of us is capable of shutting up–me least of all–so we sit down to write 6 lines and end up writing 60 or 600.
Well, not this time. Here’s BYU 12866, probably a fifth cervical, almost certainly from Brachiosaurus, plus some CT cross-sections (the cross-sections have been straightened up a little to correct distortion in the specimen; see figure 12 here for the unexpurgated version). If they haven’t been defined before, camerae are big chambers and camellae are small chambers.
Hat tip to Mike from Ottawa for the title.
Kthxbai!
Sauropod Vertebra Picture of the Week 
September 4, 2008 at 7:04 am
Right now I’m entertaining the idea that sauropods had what amount to a succession of pressurized bladders under the vertebrae, providing support, which allows the cervical ribs to have been under tension. (See the illustration in the previous SV-POW installment; doesn’t the space under the neck look oddly vacant?)
Really, the thin bits of bone remaining in a vertebra must provide a near-perfect map of the forces that acted on it in life. We ought to be able to deduce precisely what those forces were, given a full 3D scan. With the forces that must have acted on the neck as a whole, then, we should be able to tell where the muscles and air bladders were. Does anybody know a civil engineer?
Referring again to last week’s, really how much of the bone mass shown was really dug up?
September 4, 2008 at 9:49 am
Hi, Nathan.
The idea of pressurised air-sacs supporting sauropod necks has been around for a while — it’s been advocated by people like John Martin, Dino Frey and Daniela Schwarz, though so far mostly in abstracts and posters. I continue to await with interest (and I suppose I may as well say. with some skepticism) the paper that is presumably in the works that will explain and support this idea.
Essentially all of Omeisaurus is known from real bone: like Shunosaurus and Mamenchisaurus, it’s one of those gloriously complete Chinese sauropods that the world largely ignores because of its inexplicable fascination for crappy little feathered theropods.
I am VERY intrigued by your idea of reverse-engineering the forces acting on sauropod cervicals from the bone — and going on from there to think about what soft-tissue structures could have generated those forces. AFAIK, no-one is working on this and this may in fact be the first time it’s ever even been mentioned. Get yourself a grant, man, and get to work!
September 9, 2008 at 12:50 am
The pneumaticity is very interesting.
Have other large animals had pneumatic bones? Indricotheres? Elephants?
September 9, 2008 at 8:34 am
Hi, William. Lots of animals have pneumatic skulls — including humans: your sinuses (the big air-spaces behind your nose) are nothing but pneumatic camerae. But pneumaticity in the rest of the skeleton is very rare, and only known in saurischian dinosaurs (sauropodomorphs and theropods, including birds) and in pterosaurs. Since it’s found in two of the three groups of flying vertebrates, you expect postcranial skeletal pneumaticity in bats, too, but they don’t seem to have it — presumably because they don’t have the prerequisite soft-tissue structures.
September 10, 2008 at 3:20 am
OK, thank you very much.
So, two flying groups and giant dinosaurs? That’s odd. I guess birds inherited it from non-avian saurischians…
What are the prerequisite soft-tissue structures that bats don’t have?
Could that be why there are no bats nearly as big as the biggest living birds (much less teratorns or the big pterosaurs)? I’ve never heard of any fossil bats bigger than the living flying foxes — do they exist? (A quick Google search doesn’t show any, either.)
September 10, 2008 at 2:45 pm
So, two flying groups and giant dinosaurs? That’s odd. I guess birds inherited it from non-avian saurischians…
You got it in one.
What are the prerequisite soft-tissue structures that bats don’t have?
Basically, a diverticular lung. We mammals are stuck with our lungs inside our body cavities. Those critters with postcranial skeletal pneumaticity (or PSP, as the cool kids say) evolved pneumatic diverticula that can get out of the body cavity and into the skeleton.
You can read my noodlings on how this might have gone down toward the end of this paper.
Could that be why there are no bats nearly as big as the biggest living birds (much less teratorns or the big pterosaurs)? I’ve never heard of any fossil bats bigger than the living flying foxes — do they exist? (A quick Google search doesn’t show any, either.)
I have also never heard of any bats bigger than flying foxes. I’m not sure if we can chalk it up to a lack of PSP, though. There are some good-sized flying birds with no PSP (loons, for example). And the huge diversity and success of bats smaller than flying foxes suggests to me that there have been evolutionary advantages at small size, and not just constraints at large size. Darren would be the one to ask about that, so I will: what say, D-rock?
BTW, you guys have been throwing up all kinds of crazy interesting comments lately. I’ve been letting my co-bloggers field most of them because the next two months are my serious crunch-time for teaching. Any posts you see by me were written back in the summer and stashed. I’ll get back to you in earnest after Halloween.
September 11, 2008 at 5:35 pm
“That’s odd. I guess birds inherited it from non-avian saurischians…”
It’s too bad it turns out birds are descended from theropods and not from an ancestor of the saurischia. The coolest imaginable thing, apart from geting a tour of Mark Witton’s pterosaur aviary, would be if it had turned out that Brachiosaurus was a secondarily flightless bird.
This, BTW, I consider merely a crazy comment, not crazy and interesting.
Good luck with the teaching, Matt. I hope you aren’t greeted by a rush of posts to ratemyprofessors.com :-)
September 12, 2008 at 7:20 am
Pterosaur aviary? Is it as dangerous as the one in Jurassic Park?
September 13, 2008 at 2:12 am
Pterosaur aviary? Is it as dangerous as the one in Jurassic Park?
Depends. Are the animals inside as much exaggerated over their natural size and wit as the ones in Jurassic Park?
September 13, 2008 at 9:28 am
MfO: you may think that Brachiosaurus being a secondarily flightless bird is a mere crazy comment — and in truth I would not disagree — but did you know this idea has been proposed semi-formally by George Olshevsky, as the BCF (Birds Came First) hypothesis? Apparently it was proposed as a series or articles in Omni magazine, but they seem to be pretty much impossible to get hold of, and George resists publishing in a normal venue. This resistance of course has two consequences: 1, no-one outside of Internet mailing lists has ever heard of BCF; and 2, no-one’s ever had an opportunity to refute it.
September 13, 2008 at 7:25 pm
As I recall, there was something recently about a number of large dinos being pretty much secondarily flightless ‘birds’ (large size evolving multiple times in that lineage). Where did that end up when it came to (at least temporary) rest?
September 13, 2008 at 7:27 pm
And I should add that the similarities in turkey and sauropod vertebrae is one of the most literally wonderful things there can possibly be. An example of both the diversity of life and of the ties that link even the most apparently hugely disparate forms.
September 15, 2008 at 7:54 am
Well, it all depend on what you mean by “secondarily flightless bird”, which in turn depends on what you mean by “bird”. That may seem like a simple question, but Jacques Gauthier and Kevin de Queiroz wrote 35-page book chapter that discusses nothing but that … and only really discusses that candidate phylogenetic definitions.
Gauthier, Jacques A., and Kevin de Queiroz. 2001. Feathered dinosaurs, flying dinosaurs, crown dinosaurs, and the name “Aves”. pp. 7-41 in: J. A. Gauthier and L. F. Gall (eds.), New Perspectives on the Origin and Early Evolution of Birds: Proceedings of the International Symposium in Honor of John H. Ostrom. Peabody Museum of Natural History, Yale University, New Haven, Connecticut.
(It’s available at http://si-pddr.si.edu/dspace/bitstream/10088/4690/1/VZ_2001gaudeqost.pdf although none of my four PDF readers seem to be able to display it properly.)
If you adopt the definition of Chiappe (1992) of Aves as the last common ancestor of Archaeopteryx and modern birds and all its descendants, then, yes, it’s possible that quite a few well-known dinosaurs are “birds”.
But not Brachiosaurus :-)
Apropos of which, you might be interested in one of my old posts to the Dinosaur Mailing List: http://dml.cmnh.org/2007Sep/msg00374.html
September 15, 2008 at 2:45 pm
I suggest they’re missing the point: geese are secondarily flighted sauropods; turkeys somewhat less so.
September 15, 2008 at 5:37 pm
Thanks, Mike. I contacted the Smithsonian about the bad pdf (it’s a font problem in the file) and one of their librarians kindly sent me copy that opens fine. Hopefully they’ll have that version up on the site soon.
BTW, I posted the turkey C7 and it passed largely without notice. Sigh. Some folk just have an underdeveloped sense of wonder.
September 17, 2008 at 5:05 pm
A fixed copy (i.e. it reads in my Acrobat Reader 8.1.2) of the Gauthier, de Queiroz paper is up at http://si-pddr.si.edu/dspace/handle/10088/4690 .
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