Last time we looked at the humeri in the Field Museum’s mounted Brachiosaurus skeleton — especially the right humerus, which is a cast from the holotype, while the left is a sculpture. But Matt’s and my photos of that mount are all pretty much useless scientifically — partly because we were terrible photographers back then, but also partly because the very light background of sky tended to put the skeleton into silhouette and lose a lot of detail.

But fortunately there’s another Brachiosaurus in Chicago!

dscn1156

(We’ve featured this mount once before.)

This in fact the original Brachiosaurus mount that was erected in the Field Museum’s main hall in 1993. When a certain vulgar, over-studied theropod was installed in that hall in 2000, the surprising decision was made to remove the Brachiosaurus to “make room” for it (even though it’s objectively tiny). The mount was not built to be exposed to the elements, so it couldn’t just be moved outdoors. Instead, a new one was made from more suitable materials for the picnic area, and the original mount was moved to O’Hare Airport.

[Aside: what the heck were the museum thinking when they booted Brachiosaurus out of the main hall? However much you love T. rex, and I admit I do, Sue makes a feeble centrepiece compared with a brachiosaur. I can only assume there was some subtle political motivation for reducing their main hall’s Awesome Quotient so dramatically. The poor thing was only there seven years.]

Anyway, the original mount is now at Terminal 1 at O’Hare Airport, where it can be photographed less inadequately than outdoors. Here are those contrasting humeri again: the real cast on the right side of the animal (left side of photo) and the sculpture on the left (right side of photo):

dscn1158

And a zoom into the relevant section:

dscn1158-closeup

As it happens, I flew into a different terminal at O’Hare. But I knew that this mount was in Terminal 1, so before I get the transit to my hotel, I dragged my luggage across to Terminal 1 and begged the ticket clerk to let me through into the departure area so I could look at it. I don’t now remember exactly what the sequence of events was, but I do recall that phone-calls were made and supervisors were consulted. In the end, someone on staff gave me a platform ticket, and I was able to go and spend a quality hour with this glorious object.

It also meant I got to watch nearly every single traveller amble straight past Brachiosaurus giving it literally not even a single glance — see the first photo for an example. Truly depressing.

Anyway, I was able to get some slightly better photos of this cast humerus than I subsequently got of the outdoor mount. Though not very many, because — stop me if you’ve heard this — I was young and stupid then.

Anyway, here is the humerus in anterior view. Or as close to anterior as I could manage. By holding the camera above my head, I could get it nearly level with the distal margin of the mounted bone, so what we have here is really more like anterodistal:

dscn1161-brightened

And here is that some bone in lateral view (again, really laterodistal). From this angle, you can really see how shapeless parts of the lateral border of the cast are — which is odd, because there are sharp lips on the actual fossil.

dscn1163

In terms of general appreciation of the bone, this next one, in anterolaterodistal view,  is probably best — the light caught it in an informative way. Unfortunately, I cut off the distal margin. Sorry.

dscn1164

As you can see, the level of detail in the cast is mostly pretty good. For example, you can clearly make out the broken-off base of the deltopectoral crest (the tall light-coloured oval about a quarter of the way down and a third of the way across the bone). That makes the lumpenness of the distal part of the lateral aspect all the more mysterious.

Finally, here are both humeri, more or less from the left, so that the real cast is in something approaching medial view.

dscn1165

From this angle, you can see that the humerus is noticeably less anteroposteriorly deep than its transverse width. We’ll see this theme cropping up again with brachiosaur limb bones — stay tuned for future posts!

Also of interest: the very nice sculpted humerus on the left side has a complete deltopectoral crest — modelled, I imagine, after those of the various Giraffatitan humeri. It also has a finished distal end which is much broader than that of the cast humerus. In this, it’s probably right, as the real bone suffered from some decay.

And that, I am afraid, is all: stupidly, I neglected to photograph the humerus in posterior aspect, or any of the diagonals other than anterolateral.

Next time: exciting news about the relative breadth of humerus and femur in brachiosaurs!

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).

dscn9650

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:

dscn9672

(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:

dscn9672-close-up

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:

Utah 2008 07 Matt in lift

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.

In the comments on Matt’s post about the giant new Argentine titanosaur specimens, Ian Corfe wondered why Benson et al. (2014) estimated the circumference of the humerus of Brachiosaurus altithorax instead of just measuring it. (Aside: I can’t find that data in their paper. Where is it?)

I replied:

Yes, the humerus is half-encased in a jacket, face down (we should post photos some time), which would make the circumference impossible to measure directly. But the mounted Brachiosaurus skeleton right outside the Field Museum (and the identical one at O’Hare Airport) have casts of that humerus, so measuring the circumference shouldn’t require any equipment more exotic than a stepladder. Maybe the anterior aspect was sculpted — but I doubt it, as there certainly was a time when the humerus was out of its jacket and mounted vertically.

Here is the evidence that the humerus wasn’t always in that jacket (from Getty Images):

Femur of Apatosaurus and right humerus Brachiosaurus altithorax holotype on wooden pedestal (exhibit) with labels and 6 foot ruler for scale, Geology specimen, Field Columbian Museum, 1905. (Photo by Charles Carpenter/Field Museum Library/Getty Images)

Femur of Apatosaurus and right humerus Brachiosaurus altithorax holotype on wooden pedestal (exhibit) with labels and 6 foot ruler for scale, Geology specimen, Field Columbian Museum, 1905. (Photo by Charles Carpenter/Field Museum Library/Getty Images)

I have no idea why it was put back in a plaster jacket: does anyone?

Back in 2005, when Matt and I visited the Field Museum, the staff were amazingly, almost embarrassingly, helpful. They mounted a whole elaborate project to remove the humerus jacket from the cabinet that held it, so we could get a better look:

dscn1375

Unfortunately, Matt and I were doofuses back in the day: terrible photographers who knew embarrassingly little about appendicular material. So nearly all of our photos are worthless. Here is a rare nice one, showing the humerus in posterodistal aspect. You can see how layers have flaked away towards this end:

dscn1382

Here is the humerus in proximal view — something that’s relevant to my interests, as at tells us about the area of articular cartilage where it connected to the shoulder:

dscn1385

And finally — because it would be rude not to — here is Matt, going the Full Jensen with the humerus:

dscn1395

Next time: what we can learn about the humerus from the mounted skeleton outside the museum!

References

Benson Roger B. J., Nicolás E. Campione, Matthew T. Carrano, Philip D. Mannion, Corwin Sullivan, Paul Upchurch, and David C. Evans. (2014) Rates of Dinosaur Body Mass Evolution Indicate 170 Million Years of Sustained Ecological Innovation on the Avian Stem Lineage. PLoS Biology 12(5):e1001853. doi:10.1371/journal.pbio.1001853

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.

 

Today sees the publication of the new Journal of Vertebrate Paleontology, and with it my paper on the two best-known brachiosaurs and why they’re not congeneric (Taylor 2009).  This of course is why I have been coyly referring to “Brachiosaurus” brancai in the last few months … I couldn’t bear to make the leap straight to saying Giraffatitan, a name that is going to take me a while to get used to.

But before we go lunging into the details, here is my skeletal reconstruction of Brachiosaurus proper, taken from the paper:

Taylor-SVP-Brachiosaurus-fig7-reconstruction-R3-480px

Skeletal reconstruction of Brachiosaurus altithorax, with Homo sapiens and Canis familiaris for scale, from Taylor (2009:fig. 7). White bones represent the elements of the holotype FMNH P 25107. Light grey bones represent material referred to B. altithorax: the Felch Quarry skull USNM 5730, the cervical vertebrae BYU 12866 (C?5) and BYU 12867 (C?10), the “Ultrasauros” scapulocoracoid BYU 9462, the Potter Creek left humerus USNM 21903, left radius and right metacarpal III BYU 4744, and the left metacarpal II OMNH 01138. Dark grey bones modified from Paul’s (1988) reconstruction of Giraffatitan brancai. Scale bar equals 2 m.

Those of you familiar with Greg Paul’s classic reconstruction of Giraffatitan brancai will immediately recognise that Real Brachiosaurus is rather differently proportioned, especially in having a longer torso and tail.

This paper has been in the works for some time, and while it was in review and then in press at JVP, it led a double life as Chapter 2 of my dissertation.  (For most of its gestation period, the paper’s title was just “Brachiosaurus brancai is not Brachiosaurus“, and the folder where I keep all the project files is still called “bb-is-not-b”).  In the end, I chickened out and went for a longer, more formal, title.

So why are the two species not congeneric?  Well, it’s a long story, and you can read about the detail in the paper, but the bottom line is that virtually every bone that is known from both species differs in significant respects between them.

Of course, I am not the first to suggest that the African brachiosaurid that we know and love isn’t exactly Brachiosaurus.  Credit for that goes to Greg Paul, who more than twenty years ago executed a then-new skeletal reconstruction of that species (the very same reconstruction that is now considered the classic), and in doing so noticed some differences between the American type species Brachiosaurus altithorax and the African referred species “Brachiosaurus” brancai (Paul 1988).  Paul hedged his bets, though: rather than erect a new genus for the African animal, he proposed a subgenus Brachiosaurus (Giraffatitan), so that the full name of the species would become Brachiosaurus (Giraffatitan) brancai; and that of the type species would become Brachiosaurus (Brachiosaurus) altithorax.  Unsurprisingly, this cumbersome nomenclatural scheme did not catch on, and I have not been able to locate a single subsequent reference to these subgenera in the literature.

xxx

Second caudal vertebrae of Brachiosaurus altithorax and Brachiosaurus brancai, equally scaled, from Taylor (2009:fig. 3). A, B, B. altithorax holotype FMNH P 25107; C-G, B. brancai referred specimen HMN Aa. A, C, posterior; B, D, F, right lateral; E, G, anterior. A-B modified from Riggs (1904:pl. LXXV); C-E modified from Janensch (1950a:pl. 2), F-G modified from Janensch (1929:fig. 15). Scale bar equals 50 cm.

That didn’t mean the idea was dead, though: three years later, George Olshevsky’s self-published mega-revision of dinosaur taxonomy proposed raising the name Giraffatitan to genus level (Olshevsky 1991).  Although this genus became popular on the Internet (it cropped up, for example, in Mike Keesey’s much-lamented Dinosauricon web-site), it was almost completely ignored in the technical literature, and even Greg Paul himself subsequently seems to have reverted to using the name Brachiosaurus brancai (e.g. Paul 1994:246).

Why was the new name overlooked?  Partly, I suspect, just because it’s so butt ugly — everyone knows and loves Brachiosaurus brancai, and the name itself has a definite poetry to it that Giraffatitan sorely lacks.  But mostly it’s because Paul didn’t really make a case for the separation that he proposed — wrongly stating, for example, that “the caudals, scapula, coracoid, humerus, ilium, and femur of B. altithorax and B. brancai are very similar” (Paul 1988:7).

That’s how things stood a few years back when I started to take a serious interest in Migeod’s Tendaguru brachiosaurid, which lives in the basement of the Natural History Museum in London.  It quickly started to seem to me that it wasn’t the same thing as what everyone means by Brachiosaurus, but to make sense of it all, I needed first to figure out what the Brachiosaurus actually does mean.  That meant visiting the type material of both species, in Chicago and Berlin, and really looking closely.

Well, I don’t want to go on all day — apart from anything, England play Croatia in a World Cup qualifier in just over an hour — so I’ll just show you some of the the differences between the dorsal vertebrae of the two species.  (You’ll have seen the caudals up above — I just threw them in to break up all that text).

xxx

Dorsal vertebrae of Brachiosaurus altithorax and Brachiosaurus brancai in posterior and lateral views, equally scaled, from Taylor (2009:fig. 1). A, B, E, F, I, J, M, N, B. altithorax holotype FMNH P 25107, modified from Riggs (1904:pl. LXXII); C, D, G, H, K, L, O, P, B. brancai lectotype HMN SII, modified from Janensch (1950a:figs. 53, 54, 56, 60-62, 64) except H, photograph by author. Neural arch and spine of K sheared to correct for distortion. A, D, E, H, I, L, M, P, posterior; B, F, G, J, N, right lateral; C, K, O, left lateral reflected. A, B, dorsal 6; C, D, dorsal 4; E-H, dorsal 8; I-L, dorsal 10; M, N, P, dorsal 12; O, dorsals 11 and 12. Corresponding vertebrae from each specimen are shown together except that dorsal 4 is not known from B. altithorax so dorsal 6, the most anterior known vertebra, is instead shown next to dorsal 4 of B. brancai. Scale bar equals 50 cm.

Lots and lots of differences here — I will quote from the Systematic Paleontology section on the type species: “Postspinal lamina absent from dorsal vertebrae (character 130); distal ends of transverse processes of dorsal vertebrae transition smoothly onto dorsal surfaces of transverse processes (character 142); spinodiapophyseal and spinopostzygapophyseal laminae on middle and posterior dorsal vertebrae contact each other (character 146); posterior dorsal centra subcircular in cross-section (character 151); posterior dorsal neural spines progressively expand mediolaterally through most of their length (“petal” or “paddle” shaped) (character 155); mid-dorsals about one third longer than posterior dorsals (see Paul, 1988:7); middorsals only about 20% taller than posterior dorsals (see Paul, 1988:8); dorsal centra long (Janensch, 1950a:72) so that dorsal column is over twice humerus length (Paul, 1988:8); transverse processes of dorsal vertebrae oriented horizontally (Paul, 1988:8); dorsal neural spines oriented close to vertical in lateral view; dorsal neural spines triangular in lateral view, diminishing smoothly in anteroposterior width from wide base upwards; deep inverted triangular ligament rugosities on anterior and posterior faces of neural spines” …. *gasp*

So anyway: the upshot of all this is that “Brachiosaurus” brancai differs from Brachiosaurus altithorax more than, say, Barosaurus does from Diplodocus; and so it must be placed in its own genus … and that genus has to be Giraffatitan, because of the ICZN’s principle of priority.  And THAT is why the very end of the paper — the last sentence of the Acknowledgements — reads:

Finally, I beg forgiveness from all brachiosaur lovers, that so beautiful an animal as “Brachiosaurus” brancai now has to be known by so inelegant a name as Giraffatitan.

Anyway, go and read the paper; full-resolution figures are freely available if you want to look more closely than the JVP’s PDF allows.

References

(And, yes, Randy, I know what your comment is going to say; go ahead and say it anyway, it’ll give me a chance to explain why your approach is wrong :-))

Considering how much time I’ve spent playing around mounted sauropod skeletons, I cannot believe it never occurred to me to do this:

This is the mounted Brachiosaurus skeleton in the United terminal at Chicago O’Hare. It used to be in the main hall of the Field Museum, but they booted it out to make room for some vulgar overstudied theropod (ht to Paul Barrett for that supremely useful phrase). The indoor version was moved to O’Hare, and they made a second, weatherproof cast which is now mounted outside the northwest corner of the Field Museum.

We spend so much time looking at drawings or photos of bones or entire skeletons in lateral view. It is nice to get a kick-in-the-brainpan reminder that sauropods existed in 3D. And it is always rewarding to see something familiar from a new angle.

Lots of good stuff here. Anterior is toward the bottom of the photo; you can see the scapulae arcing back over the anterior ribs, the coracoids sternal plates converging and disappearing out of the bottom of the image, and the humeri angling out to either side. The thing does not really sprawl as much as it might seem from this picture–keep in mind that there is a lot of vertical foreshortening going on. Speaking of, you can see the neck zooming off into space at the bottom center. At the top of the image you can see the sacrum and the preacetabular blades of the ilia flaring out to either side.

The seven posterior dorsals are cast from the holotype of Brachiosaurus altithorax, as are the sacrum, the first couple of caudals, one humerus, one ilium, and one femur. The rest of the mounted skeleton is either mirrored from available elements or subbed in from Brachiosaurus brancai.

I’m posting this because (a) it’s a really cool photo, and (b) it illustrates something peculiar, which is that the dorsal vertebrae of Brachiosaurus are oddly–one might even say freakishly–slender. This is true of both the B. altithorax and B. brancai dorsals. I was recently standing under yet another copy of this skeleton and someone I was with asked if those were even the right vertebrae, because even to non-specialists they look too small.

I WILL have more to say about that one of these days, but for now just dig the austere beauty.

Photo (c) Tristan Savatier – www.loupiote.com – Used by permission.

In the last post, Matt promised you non-brachiosaurs, sacrals and caudals. And so I bring you the gift of … brachiosaur dorsals! Feast your eyes, gloat your soul, on the last four presacral vertebrapresacral vertebrae 4-7 of the Brachiosaurus altithorax holotype FMNH P25107.  [My mistake — for some reason, I called these the last four when I originally wrote this post.  Now fixed — Mike, 11 September 2009.]

boba-dorsals-500px.jpeg

These bones form part of the first brachiosaurid sauropod ever described. It was initially reported by Elmer S. Riggs in 1901, described and named by him in 1903, and described in more detail, again by Riggs, in 1904.

It’s still one of the best brachiosaurid specimens, consisting of the last seven dorsal vertebrae, sacrum, first two caudals, left coracoid (NOT right as stated by Riggs), right humerus, ilium and femur, and ribs. Sadly no skull elements or cervicals, though.

Here we see the bones in an oblique left anterodorsolateral aspect, with your humble chronicler in the background, measuring something so quickly that motion blur hides his craggy, manly features. That I am in the photo means that Matt must have taken it. It’s one of 122 photos that we took of these dorsals, in a single long, crazy day that, apart from brachiosaur dorsals, was also filled with brachiosaur humeri, giraffe cervicals and Godzilla rolls (sushi). Ah, happy days!