The humerus of Brachiosaurus altithorax, part 2: the museum mount
May 21, 2014
As we noted yesterday, the humerus of the Brachiosaurus altithorax holotype FMNH P25107 is inconveniently embedded in a plaster jacket — but it wasn’t always. That’s very strange. I have an idea about that which I’ll come to later.
Anyway, although the humerus is now half in a jacket and fully inside a cabinet, we can see it from all angles thanks to the cast that’s part of the mounted skeleton outside the Field Museum. (I can definitively state that this is the greatest picnic area in the universe).
As noted in the previous post, Matt and I were idiots back when we visited Chicago, so our photos are mostly useless. We have lots that show the mounted skeleton as art, but very few that are scientifically useful. But what you can make out from the photo above (especially if you click through) is that the textures of the two humeri are very different.
You can see it more clearly from in front:
(There I am, microscopic and easily overlooked, on the left.)
Here’s a close-up of the humeri from that photo, sharpened and contrast/brightness-balanced so you can more easily see what’s going on:
Contrast the scarred, pitted surface of the right humerus (on the left of the picture) with the much cleaner and bone-like texture of the left one (on the right of the picture). What’s going on here is that the right humerus of the mounted skeleton is a cast of the original element (bad preservation and all) whereas the left humerus is a sculpture. (Or possibly a cast of one of the Giraffatitan humeri, but I doubt that — it’s a bit too clean and seems more robust than those bones.) The real humerus is very distinctive, especially in the progressive flaking away on the lateral side of the distal end.
Of course you can walk all around the cast humerus and photograph it from every angle — both the posterior that is apparent in the jacket, and the anterior that’s face down and inaccessible.
You can walk all around the cast humerus and photograph it from every angle. But we didn’t. Because, as noted here and yesterday (and previously, come to think of it) we used to be idiots back then. As Matt has pithily observed:
“About every three or four months I realize that I’ve spent my entire life up until now being a dumbass; the problem is that ‘now’ keeps moving and every time I think I’ve finally got everything figured out, I later determine that I was/am still a moron. I distinctly remember having this feeling for the first time in third grade, age of eight, and I keep hoping it will eventually go away, but that hope seems increasingly unfounded.”
That is a hauntingly familiar feeling.
It seems that this cast-right, sculped-left humerus combo is common in Brachiosaurus mounts — I guess because they’re all cloned from the Field Museum’s original. Here, for example (from this post) is the mount at BYU the North American Museum of Ancient Life:
Once you’ve seen that humerus mismatch, you can’t miss it.
Finally, then — what about this historical oddity that the humerus was once out of its jacket but is now back in? That doesn’t make a lot of sense to me. I can’t really imagine why you’d do that.
So maybe that never happened? We’ve been taking it for granted that the humerus in the old Field-Museum photo is real, but maybe it’s not. Maybe it was a cast, and that cast is still somewhere in the museum (or indeed incorporated into the mount). Maybe when the fossil humerus was brought back from the field, the jacket was removed from the anterior face and that was cast; then this face was rejacketed, the bone was flipped, the posterior face was exposed (as it still is today) and that was cast. Then the two casts were joined together to make an apparently whole humerus.
If that speculation is right, then it should be possible to detect a join running down the lateral and medial faces of the cast humerus that’s in the mount (and apparently in all other mounts). That’s something I’ll look closely for the next time I’m lucky enough to be in Chicago.
I wish it was possible to know this kind of thing. I’d love it if every time a museum mounted a skeleton they published an account of how it was done, as Janensch (1950b) did for the original Giraffatitan mount in Berlin, and Remes (2011) did for the recent remount. Unfortunately I’ve never heard of such a paper regarding the Chicago mount, and I don’t even know how long ago it was done (or if anyone who was involved is still alive). The Wikipedia page says the mount went up in 1993, but gives no reference for that and doesn’t say who did it. Does anyone know?
Update (11:38pm)
Thanks to Ben (no surname given), whose comment below points to a useful 1993 Chicago Tribune article, “Brach To The Future“. This confirms the date of the mount as 1993, unveiled on Saturday 3rd July. The mount is the work of PAST (Prehistoric Animal Structures, Inc.), who bizarrely don’t seem to have a web-site. PAST president Gilles Danis was involved in the process, so he’d be the person to contact about how it was done.
Oh, and here’s another relevant Tribune article: “Out Of The Past“. Steven Godfrey is the key player in this account, so he’s someone else to track down.
References
- Janensch, Werner. 1950b. Die Skelettrekonstruktion von Brachiosaurus brancai. Palaeontographica (Supplement 7) 3:97-103, and plates VI-VIII.
- Remes, Kristian, David. M. Unwin, Nicole. Klein, Wolf-Dieter Heinrich, and Oliver Hampe. 2011. Skeletal reconstruction of Brachiosaurus brancai in the Museum für Naturkunde, Berlin: summarizing 70 years of sauropod research. pp. 305-316 in: Nicole Klein, Kristian Remes, Carole T. Gee, and P. Martin Sander (eds.), Biology of the Sauropod Dinosaurs: Understanding the Life of Giants. Indiana University Press, Bloomington and Indianapolis.
Sauropod Vertebra Picture of the Week 
May 21, 2014 at 12:15 pm
All 2 (two) of my Chicago museum mounted Brachiosaurus pics are also ‘art’ rather than science; in one, the big lump is staring pensively out across the Chicago downtown skyline… You can (just) see the differences between humeri, and also the relative gracility of femur vs hunerus – though given the perspective and orientation I don’t think it’s too helpful. I think I only took 2 pics because I had to jump a fence and walk on a lawn to get the perspective I wanted and was frowned at by a guard, so I quickly went back into the museum to look at the teeth of smaller beasts in the collections!
These differences in the cast humeri, and the possible errors with the Giraffatitian femur:humerus circumference measurements, drive home that you really do need to be very careful with the measurements when extrapolating mass from just 2 datapoints, in comparison to the volumetric methods where it’s the ‘fatness’ and pneumatisation parameters that seem to have most effect but individual bone measures in the initial scanning likely have limited effect on final mass estimates. And the taxa in Benson et al 2014 where only one circumference is known, and the other estimated from either two or even only one width (ant-post vs medial-lateral) measurements are potentially even more shaky.
I’ll read Remes et al. later today to see if humeri and femurs are all from the same individual and all real in the current Berlin Giraffatitan mount.
May 21, 2014 at 1:30 pm
I am trying to imagine a situation where I would walk away from the brachiosaur mount to look at mammal teeth, and failing,
Absolutely agreed (needless to say) — mass estimates based on a single measurement of a single bone are pretty terrifying.
Finally — Janensch covered in detail what was and wasn’t real in the Berlin, and which specimens/quarries the various non-S II elements were from. The new mount uses exactly the same fossil material (with some new and much better sculptures) so everything he wrote in 1950 still pertains.
May 21, 2014 at 3:59 pm
I suspect the humerus and femur in the old field museum photo were indeed casts, because it looks like they should have holes drilled into their distal ends to accommodate the three posts there and still be able to stand up straight. The real humerus lying in the plaster jacket doesn’t have any holes at the bottom end, doesn’t appear to be tampered with by drills.
Not having seen most original specimens in person, I wonder how many of the early mounts actually had drilled bones, and how many used casts. Based on photos of older mounts in various museums, I don’t see much evidence of original fossils being mutilated like that, although Jack Horner in “The complete T. rex” implied that it happened a lot and that’s why he doesn’t like mounted skeletons in general. The old mounts weren’t as advanced as the new RCI ones, but did they really damage the original fossils in order to mount them?
May 21, 2014 at 4:07 pm
I think you have a good point, Nima — I wonder if anyone from the Field Museum can comment?
On the more general question of how often bones were mutilated for mounting: I don’t know how common it was, but it did happen for sure. They did all sorts of stuff to the Brontosaurus holotype YPM 1980.
May 21, 2014 at 7:03 pm
According to this quintessentially 90s Chicago Tribune article, the Brachiosaurus mount was the work of Gillis Danis of Prehistoric Animal Structures, Inc in 1993.
http://articles.chicagotribune.com/1993-07-02/entertainment/9307020112_1_field-museum-dinosaur-jurassic-park
Im also pretty sure Triebold Paleontology sells casts if the mount, so it might be worth getting in touch with them?
May 21, 2014 at 7:18 pm
Mike – they weren’t proper mammal teeth, and not even mammaliaform teeth – these were non-mammaliaform synapsid teeth! Here’s ‘The pensive brachiosaur’:
Remes et al 2013 openly admit that Janensch 1950 covered everything in detail, but state that they hope to make it more freely available (by which I guess they mean not in German and in a book, though that’s possibly less available than the original if that is now available as PDF!). My German’s rusty and I had the book on the shelf right above my desk so I didn’t even have to get up to grab it!
They note that both mounted Giraffatitan humeri are original bone from SII, but that the left femur is a partial SII bone completed with plaster, and the right is bone but from the Tendaguru site ‘Ni’ so presumably not SII.
I didn’t find if they mention whether the left femur plaster was altered during the remounting. Mike or Matt should know if the left femur minimal diameter region is completely bone or not, and intact or not. From that we should be able to tell whether the relatively low/equal femur minimum circumference to humerus minimum circumference of 1.12 for Giraffatitan is an artefact of a reconstructed femur or a femur from a different individual (possibly smaller than the real one if it lowers the ratio?), or a measurement error, or actually ‘true’…
May 21, 2014 at 8:06 pm
I don’t know about the old photo, but I don’t think the humerus is in a field jacket, I think it’s just lying on a collections jacket to support it so it won’t break – seeing the other side should be no more difficult than getting out a whole mess of bean bags or other padding and rolling it over. I may know someone I can ask to confirm it, but that’s a common practice.
In fact, it’s tragically not unheard of to embed important (even type) specimens in all sorts of crazy stuff, like these images of the type of “Seismosaurus” show:
http://www.nmnaturalhistory.org/seismosaurus-vertebrae-from-the-tail.html
http://www.nmnaturalhistory.org/seismosaurus-hip-vertebrae-and-ilium.html
On that last one ignore the pelvis (which is just sitting on the cement) and gaze in horror at the vertebrae on the lower right of the image. And yes, those are the real bones.
And don’t even get me started on what happened to some of the original Shunosaurus material…
May 21, 2014 at 10:05 pm
Thanks for the links, Scott. What are we seeing there–are those the original fossils embedded in some kind of faux stone to make the display? WhatisthisIdon’teven
May 21, 2014 at 10:20 pm
Yes Matt, those are the real bones from the “Seismosaurus” specimen, and they are embedded to greater and lesser degrees in a cement-based faux rock display. Dave Lovelace went down there to photograph the specimen so we could check the coding and they were already like that over a decade ago.
May 21, 2014 at 10:23 pm
Scott: you have brought new sadness into my life.
How how how could this have happened?
May 21, 2014 at 10:32 pm
Ian, a very good English translation of Janensch (1950b) is freely available on the Polyglot Paleontologist site.
I’m glad to see that the Remes et al. account corrects an error Janensch which I pointed out in 2009 paper (p.799) — he reversed which femur was partial one from S II and which was a complete (and slightly smaller) one from Ni.
If the plaster reconstruction was redone (which seems unlikely) I’m sure Remes et al. would have mentioned it.
May 22, 2014 at 4:00 am
“In fact, it’s tragically not unheard of to embed important (even type) specimens in all sorts of crazy stuff”
The same thing happened to the Sinraptor and Monolophosaurus holotypes, so that when Brusatte et al. (2010) and Zhao et al. (2010) redescribed the latter, one half of the skeleton was inaccessable. If the IVPP’s not going to remove the mess for Currie, Zhao, Brusatte and Benson, who WILL be the ones to have access to the whole fossil?
May 22, 2014 at 5:00 am
>>And don’t even get me started on what happened to some of the original Shunosaurus material…
So what DID happen to it? Broken up for gravel? Shot out of a cannon?
May 22, 2014 at 5:52 am
Thanks for the info Mike, that probably is more accessible than the Remes chapter in the sauropod book in that case.
If the Ni femur is slightly smaller, and was measure in for the Campione & Evans 2012 paper, that would explain the low FC:HC ratio. Do you know what the condition of the SII femur is, would you be able to get a reliable minimum circumference measure from complete bone rather than damaged bone (under sized) or partially/wholly plaster (potentially undersized or oversized)?
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