In recent photo posts on the mounted Brachiosaurus skeleton and its bones in the ground, I’ve lamented that the Field Museum’s online photo archive is so unhelpful: for example, if it has a search facility, I’ve not been able to find it.
But the good news is that there’s a Field Museum Photo Archives tumblr. Its coverage is of course spotty, but it gives us at least some chance of finding useful brachiosaur images. Like this one of the sixth presacral vertebra (i.e. probably D7 in a column of 12 dorsals):
It’s instructive to compare that with Riggs’s (1904: plate LXXII) illustration of the same vertebra in the same aspect, in which he almost literally airbrushed out the jigsaw-puzzle complexity of the preserved bone surface:
More disturbing still, compare that old photograph with my own (terrible) 2005 photo of the same vertebra:
It looks very much as though the vertebra itself — not just Riggs’s illustration — has been “improved” since the older photo was taken exactly a century earlier in 1905. This is a constant problem when dealing with old fossils.
Here are three more interesting photos from the Tumblr. First, the Brachiosaurus fossils in the field:
This is evidently from later in the excavation process than the previous photo of this area, since much of the material is now jacketed. That’s the femur in front of shot, here seen in anteromedial view, with the top towards the right.
Next up, this photo purports to be “Thirteen men including Security Guard unloading dorsal vertebrae of type specimen Brachiosaurus fossil”:
But in fact it’s not Brachiosaurus — the neural spines are too tall and slender. I am pretty sure this is Riggs’s Apatosaurus — the rightmost dorsal has that distinctive notch on the dorsal aspect of the neural spine. And indeed, checking his monograph on that specimen (Riggs 1903: plate XLVI), I see that its dorsals were distorted in this way, and that the front-centre vert is a fine match for its D10.
Finally, there’s this one of the prep room:
On the far left, we have the still-jacketed Brachiosaurus femur; next to it stands Harold W. Menke, who discovered the fossil; and to his right is Elmer S. Riggs, who wrote the description.
Those are all the Brachiosaurus-related images I’ve been able to find on the tumblr. But do let me know if you find any others.
References
- Riggs, Elmer S. 1903. Structure and relationships of opisthocoelian dinosaurs. Part I: Apatosaurus Marsh. Field Columbian Museum, Geological Series 2:165-196.
- Riggs, Elmer S. 1904. Structure and relationships of opisthocoelian dinosaurs. Part II, the Brachiosauridae. Field Columbian Museum, Geological Series 2:229-247.
Brachiosaurus altithorax, fossils in the field
June 3, 2014
Continuing our Brachiosaurus series [part 1, part 2, part 3, part 4, part 5, part 6, part 7], here is another historically important photo scanned from the Glut encyclopaedia: this time, from Supplement 1 (2000), page 157.
This is the Brachiosaurus altithorax holotype FMNH P25107 in the field, at Grand Junction, Colorado, in 1900. Clearly visible are the seven presacral vertebrae running across the middle of the photo (upside-down, so we see their ventral surfaces), several ribs on either side, and the end of a long-bone to the left — most likely the distal end of the femur. The flat bone at bottom left is probably part of the ilium, with the circular cut-out being the acetabulum. (The caption also mentions the sacrum, which I can’t see.)
As with the photo of the mounted skeleton in the museum, this is one of the Field Museum’s own photos — neg. #4027 — but I can’t find a better copy online. It’s got to be out there somewhere — can anyone help?
References
Glut, Donald F. 2000. Dinosaurs: The Encyclopedia: Supplement 1. McFarland & Company, Inc., Jefferson, North Carolina. 442 pages.
I’m currently writing a popular guide to dinosaurs, to be published by Random House next autumn [Ed.: available now at amazon.com and at amazon.co.uk]. I’ve been writing about [Brachiosaurus and Giraffatitan], and have read your 2009 study vindicating the proposal to separate them into two genera.[…]I know you consider Brachiosaurus likely to have been bigger (and note that the specimen was not fully grown), with a longer trunk and tail – but most of the sources I can find give both animals the same body length, generally around 26m. Presumably this doesn’t reflect your work, and your calculations are different.
I replied at the time, and said that I’d post that response here on SV-POW!. But one thing and another prevented me from getting around to it, and I forgot all about it until recently. Since we’re currently in a sequence of Brachiosaurus-themed posts [part 1, part 2, part 3, part 4, part 5, part 6], this seems like a good time to fix that. So here is my response, fresh from November 2011, lightly edited.
Well, Giraffatitan has only been recognised as a separate animal at all in the last couple of years, and nearly everything that has been written about “Brachiosaurus“, at least in the technical literature, is actually about Giraffatitan. So existing sources that give the same length for both are probably not making a meaningful distinction between the two animals.
First, on Giraffatitan: Janensch (1950b:102) did a great job of measuring his composite mounted skeleton. His figure for the total length of Giraffatitan along the neural canal is 22.46 m, and is certainly the best estimate in the literature for an actual brachiosaur specimen (and quite possibly the best for any sauropod).
I don’t know where the figure of 26 m comes from, but as Janensch (1961:213) notes, the isolated fibula XV2 of Giraffatitan in the Berlin collection is 134 cm long, compared with 119 cm for that of the mounted skeleton. This is 1.126 times as long, which if scaled isometrically would yield a total length of 25.29 m. So that is defensible, but 26 m is not, really.
I would advise sticking with Janensch’s published figure of 22.46 m, as it’s based on good material, and also because it forms the basis of my comparative estimate for a Brachiosaurus of similar limb length.
Now in my 2009 paper I estimated with reasonable rigour that the torso of Brachiosaurus was probably about 23% longer than that of Giraffatitan, yielding 4.82 m rather than 3.92 that Janensch gave for Giraffatitan. On much less solid evidence, I tentatively estimated that the tail of Brachiosaurus might have been 20-25% longer than that of Giraffatitan. Given the paucity of evidence I would play safer by going with the lower end of that estimate, which would give a tail length of 9.14 m compared with Janensch’s 7.62 for Giraffatitan. Riggs (1904) tells us that the sacrum of Brachiosaurus is 0.95 m long, which is slightly less than 1.07 m for Giraffatitan. Finally, since we know nothing of the head and neck of Brachiosaurus, the null hypothesis has to be that they were similar in proportion to those of Giraffatitan.
Putting it all together, Brachiosaurus may have been longer in the torso by 0.9 m, and in the tail by 1.52 m, but shorter in the sacrum by 0.12 m — for a total additional length of 2.3 m. That would make Brachiosaurus 24.76 m long, which is 10% longer than Giraffatitan.
Note that all the Brachiosaurus figures are given with much greater precision than the sparse data we have really allows. I think you could round Janensch’s 22.46 m for Giraffatitan to 22.5 and be pretty confident in that number, but you shouldn’t really say anything more precise than “maybe about 25 m” for Brachiosaurus.
Finally, you correctly note that the Brachiosaurus specimen was not fully grown — we can tell because its coracoid was not fused to the scapula. But the same is true of the mounted Giraffatitan, so these two very similarly sized animals were both subadult. How much bigger did they get? We know from the fibula that Giraffatitan got at least 12-13% bigger than the well-known specimen, and I’d be pretty happy guessing the same about Brachiosaurus. And I wouldn’t rule out much bigger specimens, either.
References
- Janensch, Werner. 1950b. Die Skelettrekonstruktion von Brachiosaurus brancai. Palaeontographica (Supplement 7) 3:97-103, and plates VI-VIII. [English translation]
- Janensch, Werner. 1961. Die Gliedmaszen und Gliedmaszengurtel der Sauropoden der Tendaguru-Schichten. Palaeontographica, suppl. 7 (1), teil 3, lief. 4:177-235.
- Taylor, Michael P. 2009. A re-evaluation of Brachiosaurus altithorax Riggs 1903 (Dinosauria, Sauropoda) and its generic separation from Giraffatitan brancai (Janensch 1914). Journal of Vertebrate Paleontology 29(3):787-806.
Sauropod Vertebra Picture of the Week 