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This is BYU 12867–you’ve seen it here before–in dorsal view. It’s not a brilliant shot–I took it through the glass of the display case while filming a documentary at the North American Museum of Ancient Life in Lehi, Utah, in 2008. Centrum length is 94 cm, total length with the overhanging prezygapophyses is over a meter.

As promised, some thoughts on the various new brachiosaur mass estimates in recent papers and blog-posts.

Back in 2008, when I did the GDI of Giraffatitan and Brachiosaurus for my 2009 paper on those genera, I came out with estimates of 28688 and 23337 kg respectively. At the time I said to Matt that I was suspicious of those numbers because they seemed too low. He rightly told me to shut up and put my actual results in the paper.

More recently, Benson et al. (2014) used limb-bone measurements to estimate the masses of the same individuals as 56000 and 34000 kg. When Ian Corfe mentioned this in a comment, my immediate reaction was to be sceptical: “I’m amazed that the two more recent papers have got such high estimates for brachiosaurs, which have the most gracile humeri of all sauropods“.

So evidently I have a pretty strong intuition that Brachiosaurus massed somewhere in the region of 35000 kg and Giraffatitan around 30000 kg. But why? Where does that intuition come from?

I can only assume that my strongly held ideas are based only on what I’d heard before. Back when I did my 2008 estimate, I probably had in mind things like Paul’s (1998) estimate of 35000 kg for Brachiosaurus, and Christiansen’s (1997:67) estimate of 37400 for Giraffatitan. Whereas by the time the Benson et al. paper came out I’d managed to persuade myself that my own much lower estimates were right. In other words, I think my sauropod-mass intuition is based mostly on sheer mental inertia, and so should be ignored.

I’m guessing I should ignore your intuitions about sauropod masses, too.

References

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):

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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:

Riggs1904-plate-LXXII-presacral-6.right-lateral

 

More disturbing still, compare that old photograph with my own (terrible) 2005 photo of the same vertebra:

dscn1404-rotated-cropped-enhanced

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:

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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”:

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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:

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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.

 

Continuing our Brachiosaurus series [part 1part 2part 3part 4part 5part 6, part 7], here is another historically important photo scanned from the Glut encyclopaedia: this time, from Supplement 1 (2000), page 157.

Glut2000-p157--brachiosaurus-altithorax-quarry

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.

Way back in November 2011, I got this inquiry from Keiron Pim:
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.

dscn1253

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

Here is the wonderful Brachiosaurus altithorax mount in its original location, in the main hall of the Field Museum in Chicago. (Click through for full resolution.)

Glut1997-p215--brachiosaurus-altithorax-mount

I scanned this from Don Glut’s Dinosaurs: The Encyclopedia, page 215. There must be better quality versions somewhere, because this is one of the Field Museum’s own photos — negative #GN 86962 — but I can’t find it in their singularly unhelpful online photo archive.

I’m posting it because there’s an astonishing lack photos of this mount on the Internet. As I noted last time, I was only able to find this striking image:

The Brachiosaurus mount in its original position in the main hall of the Field Museum. I can't find a higher resolution version of this photo -- can anyone help?

The Brachiosaurus mount in its original position in the main hall of the Field Museum. I can’t find a higher resolution version of this photo — can anyone help?

at the miserably low resolution shown here (358×248). More generally, almost every photo of a mounted Brachiosaurus out there seems to be from either the picnic area outside the museum, or O’Hare Airport. If anyone’s able to find decent-resolution examples of this skeleton indoors, please do drop the links into a comment.

I mentioned this to Matt, and he commented:

I think that the mount got moved outside just a bare handful of years before digital cameras went from rare to ubiquitous. If the move had happened even five years later, I’ll bet there would be loads of photos of the old mount.

I’m sure he’s right. But someone must have half-decent photos from back then?

Seriously -- is this tiny photo the best photographic record we have?

Seriously — is this tiny photo the best photographic record we have?

Of course, the real question is: why did they shove the Brachiosaurus outside? It was mounted in 1994, and taken down again in 1999, so this marvellous mount — by any objective standard the single most awesome exhibit in the museum’s history — was only actually in residence for five paltry years.

The standard explanation is that it was removed “to make space for” Sue, the vulgar overstudied theropod. But a glance at the photo above shows that there was plenty of space to put in half a dozen T. rexes without needing to move the brachiosaur. I can only assume that someone realised having a brachiosaur next door would make Sue look feeble. It’s a tragedy.

Update

Thanks to Dean for finding this one: small, but beautiful.

chi-8sue20100512120107

References

Glut, Donald F. 1997. Dinosaurs: The Encyclopedia. McFarland & Company, Inc., Jefferson, North Carolina. 1076 pages.

After P.A.S.T president Gilles Danis commented on our post about the Chicago airport Brachiosaurus mount, I got into an interesting email conversation with him. Here, posted with his kind permission and only lightly edited, are his thoughts on the Brachiosaurus mount.

Brachiosaurus mount at Chicago O'Hare Airport, terminal one. Pelvis in ventral view, anterior to the left.

Brachiosaurus mount at Chicago O’Hare Airport, terminal one. Pelvis in ventral view, anterior to the left.

Gilles writes:

The story of this mount (s) is chequered. The casts of real material include the sacrum, the caudal, a number of dorsals, some rib fragments, one femur, a very badly eroded humerus and a coracoid. [Update: also the right ilium, as Gilles subsequently confirmed by email.]

On the mount that was in the museum and later was moved to the airport, we had a peculiar situation to deal with. Because museums like to have people walking under the rib cage of high sauropods, this becomes a safety hazard for two reasons. The first is that it cannot be allowed to fall on the people (obviously) and even though the cast was of light plastic, the engineers insisted in overbuilding the support (namely the legs and arms). Also because while in the Field Museum, it stood in the path of a fire exit, we had to have a certain amount of distance between the front and hind limbs (I forget the exact measurement). The only way that we could achieve that was to add two vertebrae for a total of 12 dorsals. We chose to duplicate two of real vertebrae at the lower end of the dorsal section.

The Brachiosaurus mount in its original position in the main hall of the Field Museum. I can't find a higher resolution version of this photo -- can anyone help?

The Brachiosaurus mount in its original position in the main hall of the Field Museum. I can’t find a higher resolution version of this photo — can anyone help?

The funny thing is only one person figured that one out and that was Bill Simpson the collections manager. Also to support this structure, we were asked to used way oversized steel in the limbs which meant that we had to “inflate” the real humerus and femur to accommodate the material. This is why the cast is so bad; it is half stuffing.

It is interested to see how a lie perpetuates itself. The following year, the Hayashibara museum ordered a mount of the same skeleton and they were very interested in getting the distance between the feet and manus. So we, again, had to make a Brachiosaurus limoensis.

Not satisfied with this silly situation, Disney came to us in 1996 and ordered that very same skeleton again with the stretch limo factor for another dinosaur that you walk under for the Wild Animal Kingdom park in Orlando. Up to that point, only Bill Simpson had realized the error. But I had just had it up to there with these stretch dinosaurs and revealed the problem. After that, in 1999, we replaced the skeleton in Stanley Field Hall with one on the terrace to make room for Sue the T. rex. On this Brachiosaurus, we have the normal 10 dorsals. The last Brachiosaurus we mounted is in the North American Museum of Ancient Life (N.A.M.A.L.) at Thanksgiving Point, Lehi, Utah, again a normal skeleton.

If this was not enough we restored Seismosaurus halli (now Diplodocus hallorum). This project was sponsored by a Japanese company who was to get the first mount. They took Gillette’s publication and read that the skeleton would have been 150′ long or 50 meters. We soon realized that there was a mistake, that the tail was not missing a huge section but had simply drifted away from the sacrum and the skeleton would not be even close to the predicted length. The Japanese would have none of it. After months of negotiations, we arrived at a compromise and we made the skeleton 40 meters long, 133’+ by adding some whiplash vertebrae until it was that long. By then I had had enough and threw in the towel but not before mounting another Seismosaurus for the museum is Albuquerque which is correct.

As for the Berlin brachiosaur: I spent some time in Berlin measuring, photographing and drawing (Donna Sloan did the drawing) the original material there, but they would not allow us to mould it. What I found interesting is that in 1992 when I was there, most of the skeleton of the mount was not original but it was not cast either. It was sculpted wood.

I have many more tails (pun, ha,ha) about sauropods. I should write them down sometime.

Many thanks to Gilles for allowing us to reproduce this important information.

Gilles’ list of real material that was cast for the mount includes very nearly all of the holotype FMNH P25107 — assuming that “a number of dorsals” means seven, the number that Riggs excavated and had prepared. The only fossil elements not apparently appearing are the fragmentary first caudal and the right ilium. But it seems to me from some of my photos of the airport mount (see the image at the top) that a cast of the right ilium was used. [Update: yes, Gilles confirmed by email that the right ilium was indeed cast from real material.]

Regarding the number of dorsal vertebrae: it may have been circumstances that forced P.A.S.T to give the mount 12 dorsals, but Migeod’s pre-description of the NHM’s Tendaguru brachiosaur gives good reason to think this is likely the correct count.

Similarly, although the torso was therefore longer than Gilles had intended, it might have ended up correct, as careful comparison of the lengths of the Brachiosaurus and Giraffatitan dorsals suggests that the torso of the former was about 23% longer.

To my shame, I’d not realised that the Brachiosaurus at the airport has two more dorsals than the one in the Field Museum picnic area, despite Matt having posted a ventral-view photo of the airport mount that clearly shows the twelve dorsals and a lateral-view photo of the museum mount that clearly shows ten.

When Gilles says “most of the skeleton of the [Berlin] mount was not original but it was not cast either”, I assume he’s referring to the presacral vertebrae, which as Janensch explained in his 1950 paper about that mount were too heavy and fragile to mount. The sculptures in Janensch’s mount were not particularly good, but they have been replaced by much better ones in the remount.

 

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