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Brachiosaurus altithorax hi-fi skeletal

Brachiosaurus altithorax

Family: Brachiosauridae (intermediate position)
Time: Late Jurassic, Kimmeridgian-Tithonian epochs, ~150 mya
Location: Morrison Formation (Brushy Basin member), Colorado, Wyoming and Utah, USA

*Now upgraded with additional referred specimens; skull also updated - again!* 


The original, classic namesake of the brachiosaur family, and for a long time the biggest dinosaur known (though much of what was assumed about it was actually based on its more complete African cousin Giraffatitan brancai ). First found in 1900 and described in 1903, Brachiosaurus altithorax is based mainly on the type specimen FMNH P 25107, which comprises a partial dorsal column, hip material, a humerus, femur, coracoid plate, and a rib. Despite being downright colossal, this animal, roughly 80 feet long and 37 tons, was still not fully grown.

More recently several isolated bones and a skull from Felch Quarry (long forgotten in a Smithsonian museum vault) have turned up, which may belong to Brachiosaurus or at the very least, to a closely related genus. There is also neck material from the same quarry at the Smithsonian, which may belong to this individual. The Felch Quarry skull is originally from a smaller individual about half the size of the holotype, but judging by other sauropods known from more complete growth series, the proportions of the skull probably didn't change much as the animal grew up. There is also a partial Morrison brachiosaur skull at Yale (jaws and braincase) which was discovered by O.C. Marsh in Reed Quarry in the late 1800s, well before the description of Brachiosaurus - Marsh incorrectly used this same fragmented skull as part of the basis for his bizarre and fanciful "Brontosaurus" skull reconstruction in 1883:…… . and later also mangled the Felch skull into an unnatural shape for his 1891 "Brontosaurus" diagram:… . Yale's Peabody Museum used an even more distorted and ridiculous spin-off of Marsh's 1891 version for their Brontosaurus excelsus mount:… . Interestingly some other early "Brontosaurus" mounts used a Camarasaurus-clone skull in place of this.

In an ironic mix-up of the opposite sort, the headless juvenile brachiosaur skeleton known as "Toni" was initially mistaken for a diplodocid, and commercial fossil casting companies still reconstruct it as such, though in 2010 it was redescribed as a brachiosaur in a phylogenetic analysis by Carballido, et. al., falling in most closely with B. altithorax. Indeed the robust dorsals, short sacral spines, and front-heavy ilia of "Toni" are remarkably similar to those of Brachiosaurus, and rather different from what one sees in Diplodocus and Apatosaurus, even in juvenile specimens. The long-shafted scapula is also very brachiosaurid in appearance.

The large Dry Mesa Quarry brachiosaur material discovered by Jim Jensen in the 1980s (including the huge"Ultrasauros" shoulder blade and another, less complete one) is not included here, as it probably belongs to another genus. Other recently found remains, like BYU 13023 (Curtice and Stadtman, 2001) and the LACM humerus, are probably from other brachiosaurid taxa. The Potter Creek specimen, one of the largest North American brachiosaurs on record, appears to belong in Brachiosaurus at least on the generic level. The dorsal vertebra of this specimen was heavily restored in plaster by Jensen, and may have looked more similar to B. altithorax than it currently appears in its restored state. Whether this specimen was fully grown is debatable, as no shoulder material was found. There are roughly 30 or so other partial specimens referred to either Brachiosaurus altithorax or Brachiosaurus sp. though most have never been formally published. A few are even photographically documented:… . I have used some of these (scaled to the teenage holotype) to fill in the major gaps in our knowledge of B. altithorax.

Despite its iconic popularity in books and movies, Brachiosaurus is relatively rare in the fossil record, though many undescribed brachiosaur bones which may or may not belong to it have turned up recently. It appears to have been a highland animal, avoiding the low fern prairies which were dominated by Diplodocus and Apatosaurus. As a result it may be that Brachiosaurus was actually more common than the fossil record indicates, and that a disproportionately small number of Brachiosaurus got fossilized due to being far from the lowland alluvial plains of flooding rivers which preserved most dinosaur fossils. Adults were probably too large for predators to tackle, though younger individuals faced danger from Torvosaurus and large allosaurs like Saurophagnax.

*Note: NO GSP. This is an entirely original skeletal based directly off of photos of the type and referred material, as well as some inferences from Giraffatitan and Lusotitan for elements for which photographs are unknown (mainly the lower limbs). Many Thanks to Mike Taylor of SV-POW for the photos of the referred BYU neck vertebrae. No Greg Paul skeletals were used or injured in the making of this far more accurate schematic 8-)

This skeletal has been credited by several other artists, including:…


Carballido, J., Schwarz-Wings, D., Marpmann, S. & Sander, P.M. (2010) "Systematic reevaulation of “Toni“ the juvenile sauropod from the Morrison Formation" Society of Vertebrate Paleontology Abstracts with Programs, 69A

Carpenter, K. and Tidwell, V. (1998). "Preliminary description of a Brachiosaurus skull from Felch Quarry 1, Garden Park, Colorado." Pp. 69–84 in: Carpenter, K., Chure, D. and Kirkland, J. (eds.), The Upper Jurassic Morrison Formation: An Interdisciplinary Study. Modern Geology, 23(1-4).

Curtice, B. and Stadtman, K. (2001). "The demise of Dystylosaurus edwini and a revision of Supersaurus vivianae." Mesa Southwest Museum Bulletin 8: 33–40.

Riggs, E.S. (1901). "The largest known dinosaur". Science 13 (327): 549–550.

Riggs, E.S. (1903). "Brachiosaurus altithorax, the largest known dinosaur." American Journal of Science (series 4) 15(88): 299-306.

Riggs, E.S. (1904). "Structure and relationships of opisthocoelian dinosaurs. Part II. The Brachiosauridae"…

Taylor, M.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.…
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The weight was marked too lightly.
Proper weight should be between 50 tons and 55 tons.
That's an excellent reconstruction complete with lots of useful detail. Thanks for sharing!

I note that your mass estimate is 37 tons but I can't find any tissue density anywhere. What tissue density did you assume? Thanks in advance.

RizkiusMaulanae's avatar
Question : Are brachiosaurids really capable of making the S curved neck posture ?
Paleo-King's avatar
They were, if you don't exaggerate the s-curve too much. I keep the s-curves pretty modest. It's not like they are bending their neck far back over their body like a mute swan. When you "de-crush" the neural arches the neck is actually capable of considerably more extreme bending than you see in these modest s-curves in my skeletals. This is just the likely resting posture of the neck.

People often forget that brachiosaurs weren't simply s-curved necks, but also very steep, high-shouldered platforms on which those necks rested. The spine doesn't jump from horizontal to vertical at the base of the neck - most brachiosaur necks are exiting out from a torso that's already inclined 45 degrees up. So the neck itself really only needs to bend up by 45 degrees to make it a 90-degree vertical incline to the s-curve.

In fact nearly all dinosaurs have a naturally s-curved neck, with the exception of stumpy-necked ceratopsians and ankylosaurs. Recent restorations even show the horizontal-necked diplodocids having a slight s-curve. Though the old 1990s-style gradual cantilever-upcurve used by GSP and others for diplodocids still looks nice and may be plausible too.
bLAZZE92's avatar
Do you have a reference for the Delta Giant femur?
Paleo-King's avatar
It's very obscure, almost mythical. There is a scant mention of the femur in Tracy Ford's Paleofile… and also usage of the term "Delta Giant" in Greg Paul's old 1988 paper on Brachiosaurus and Giraffatitan. Though he doesn't go into specifics about this animal and one gets the impression he basically synonymizes it with the "Ultrasauros" material. No clue if that's actually what the Delta Giant is, but I think it's more likely to be B. altithorax based on its Colorado location.

Nonetheless I doubt Tracy would mention it if it didn't exist, but you would have to ask him about specifics (if there are any - some of these bones just seem to disappear into museums and are never seen again... *B. nougaredi* cough cough ). If it is still at the USNM then I would be surprised we haven't heard more about it. They have the Potter Creek humerus, why not put this femur on display too?
bLAZZE92's avatar
Very intriguing, Paul 1988 is the first thing I stumbled upon searching the name and yes he does seem to use that name to refer "Ultrasauros". So many interesting things hidden away or lost inside museums, it isn't fair haha.
vasix's avatar
I just read in some of the comments that Toni the Brachiosaurus is probably around one or two years old, but do tell me, because I'm curious and having seen that Apatosaurus growth you think it could go for other sauropods too? Like, for instance Brachiosaurus as well or does the curve only attest to the A. excelsus that was used in that study? What do you think of it?
DinoMarioZilla's avatar
Man, your skeletals are epic! Love this Brachio!!! :) Your gallery is a great reference source for sauropod representations
SameerPrehistorica's avatar
You have updated this image..I am not sure,i think that you have reduced the length of it's neck.I remember like seeing both your Giraffatitan and Brachiosaurus to have long necks and i guess both were standing at 50 feet high.
Paleo-King's avatar
I didn't reduce the length of the neck, in fact the only time I changed it , I increased it!
It was actually quite a bit shorter in Mike Taylor's version (which is basically a mishmash of Greg Paul skeletals and drawings of the type material).

Brachiosaurus did have a shorter neck than Giraffatitan PROPORTIONAL to its body length. So both the Brachiosaurus and Giraffatitna teenage type specimens are around 50 feet tall, but the Brachiosaurus has a longer torso and tail, and is almost 10 feet longer overall.

And I am revising my Giraffatitan too, it will have even MORE extreme proportions, it turns out the tail of the type individual (long labeled separately as HMN Aa) was actually a good bit smaller than the the "HMN Fund D" tail that is frankensteined onto the Berlin mount (and it's the same tail that has been used on the display ever since the 1920s, it wasn't switched out for HMN Aa despite the 2007 remount). So expect a Giraffatitan that's even more front-heavy and has an even smaller tail (but oddly, slightly bigger ischia and pubes than previously restored - it turns out nobody doing the skeletals had actually bothered to cross-scale them with the more complete hips of HMN J2, they just guessed how big the missing bits for SII must be!).

HMN Fund D is probably from an adult or near-adult of 85-90ft. in length, Whereas HMN SII/Aa is most likely around 75ft. long (same length estimate as before despite the shorter tail, because the neck also turns out to be longer than Greg Paul though it was - Paul's version of the neck is a whole 'nother can-of-worms frankenstein job that I reject).
SameerPrehistorica's avatar
I used the Mike Taylor's version as reference.

It just seemed kind of weird for me to see a slight lengthy body for Brachiosaurus in that reference.But i will increase it's neck length and then the lengthy body will look better compared to that.This is the same body length for Sauroposeidon given in some images except the fact that it's neck was much longer.  
mystierodan's avatar
I work at The Field Museum and am very impressed with your work!  I get to hang out with the Brachiosaurus holotype every day. I look forward to more graphics!
Paleo-King's avatar
Thank you very much! Best compliment I can receive is from people who actually get down and dirty in the museum - I must be doing something right :D. Look out for more skeletals, Cedarosaurus and Sonorasaurus are in the works, and I am revising my Giraffatitan next. It turns out that beast is even MORE different proportion-wise from Brachiosaurus than anyone thought........
Kazuma27's avatar
Super-amazing, man! Love how you basically listed ALL we know about this guy :)
Paleo-King's avatar
Yes, true, I really pulled out all the stops on this one. Good thing that for my revision of Giraffatitan, the specimens are all listed in a couple of papers by the same author. Tracking down all the Brachiosaurus pieces in various museums (and this may not even be all of them - I've heard there are more than 30 specimens, some in private hands) was a real pain. :XD:
Turtleosaurus's avatar
What's the neck length difference between Brachiosaurus and Giraffatitan just out of curiosity because on sv pow the cervical vertebrae comparison (of Sauroposeidon Giraffatitan Brachiosaurus and Angloposeidon) showed Giraffatitan vertebrae as being only 33mm longer than Brachiosaurus's  I know they state the Brachiosaurus's vertebrae as being a c10 whereas Giraffatitan is a c8 but still surely the total neck wouldn't be massively different or am I barking up the tree. I've still got a lot to learn about anatomy so just tell if I'm completely off the mark.  
Paleo-King's avatar
I think you're overall on the right track. Giraffatitan's neck proportions are indeed more elongated than those of Brachiosaurus, but not by some radically high amount. It's not that Giraffatitan has a shorter neck than previously thought - quite the OPPOSITE in fact! It was longer than even Greg Paul restores it, since he inexplicably leaves out some of HMN SII and similar-proportioned specimens, and instead frankensteins HMN SI (probably a different and shorter-necked species) onto the top of the neck. But rather, what happened is that Brachiosaurus turns out to have a longer neck than most authors assumed.

Right now there is neck material of Brachiosaurus known from at least 3 specimens (4 vertebrae in total). One is a teenage specimen (the thick BYU 10th cervical that SV-POW sometimes posts pictures of) similar in size to the holotype. The second is an anterior cervical from BYU that's from a smaller animal. The third is a specimen at the Smithsonian/USNM (two vertebrae) which is even smaller than that one! Since none are fully grown, it's possible that even the rather long neck in my skeletal here (which is based on both specimens) may actually have been even longer on the holotype, not to mention an adult like perhaps the Potter creek specimen. It is known that adult sauropods tend to have proportionally more elongated necks than half-grown ones. But how rapid and extreme the change was, it hard to say. It may be that since the neck proportions don't seem to change much between the USNM and the anterior BYU cervicals, that perhaps adults didn't elongate that radically in a final growth spurt.

All the same, even these immature specimens indicate that the neck was already very long by the time the animal was around 50% adult size. Much more elongated than the hypothesized "camarasaur-like neck proportions" that many authors have been bandying about without actually studying the bones. And the large BYU vertebra is already holotype-sized so I doubt the adults would have much more extreme proportions than that. That would mean my skeletal is accurate for adult Brachiosaurus proportions too. It does rival Giraffatitan for neck length more than, say, Mike Taylor's version... So it depends on WHICH Brachiosaurus and Which Giraffatitan you compare. Assuming the holotype + the larger BYU vertebra represent animals of similar age to HMN SII, then you have teenage Brachiosaurus with a neck only a little shorter than teenage Giraffatitan.

Then again it's possible that the comparison you see may be off..... the big BYU cervical appears to have a thicker centrum than Giraffatitan HMN SII. So we may be looking at a bigger Brachiosaurus and a smaller Giraffatitan. And even then, the Giraffatitan has a longer neck. If both animals had the same centrum thickness, there would be a greater difference in neck length. But if you scale the two animals to the same overall length (not to centrum diameter) then the Brachiosaurus will have less extreme neck length, a bigger tail and longer belly, and bigger centra in both cervicals and dorsals. So that's why simply comparing vertebra length can be misleading, the centrum thickness could indicate rather different-sized animals. Giraffaittan has shockingly small centra in its dorsals. You get the idea that the top-heavy neural arches/zygapophyses are taking most of the weight, especially in the last few dorsals. D9 and D10 of HMN SII actually exhibit a very bizarre "lordosis" kink in their articulation which appears totally natural and makes the joint much stronger at the zygapophyses, to reduce stress on the centrum of D9. This feature isn't found in any other brachiosaur or any other sauropod for that matter!
Turtleosaurus's avatar
Cool thanks for reply. Can't wait till you finish Giraffatitan and Lusotitan reconstructions. Just thinking could the squatter, thicker Cervicals of Brachiosaurus mean it had a more flexible neck than the more elongated ones of Giraffatitan resulting with Giraffatitan having a stiffer straighter neck, or are the differences in the cervicals to slight to affect the neck physiology in any major way.  
Paleo-King's avatar
Thicker cervicals do not equal a more flexible neck. Quite the opposite in fact. The most flexible longs necks in the animal kingdom are those of ostriches, which have very slender cervicals relative to body size.
Conversely, Apatosaurus has very thick cervicals (and deep) and because of this, the range of motion is far more limited - they can't turn too far without colliding with the cervical ribs or other protruding parts of another vertebra.

In the comparison of Brachiosaurus vs. Giraffatitan, it's therefore likely that Giraffatitan had the more flexible neck, but probably not by much. Both animals had long cervicals and relatively flexible necks. However, the larger BYU cerivcal, if it's Brachiosaurus, indicates that this animal had a bit less flexibility than Giraffatitan for another reason - the cervical rib's anterior portion is much thicker and therefore less flexible. Something similar is present in the cervical ribs of Euhelopus, yet its higher vertebra count makes up for this in flexibility. The real secret of flexible necks appears to be slender cervicals, and lots of them.
Turtleosaurus's avatar
I wonder why Giraffatitan and Brachiosaurus had these different adaptations with Giraffatitan obviously being more height oriented  with being a more "extreme animal" "longer arms, longer neck" and Brachiosaurus being stouter and tubbyer, probably a reflection of their environmental pressures?
Paleo-King's avatar
Possibly. Giraffatitan was a more tropical-latitude animals, and it was coastal, whereas Brachiosaurus was a highland dweller. Different types of forest, different environments.

However this by itself is not enough to explain the difference. There are some Giraffatitan-like (and some Archbishop-like) vertebrae known from the Morrison formation, so Brachiosaurus was not the only brachiosaur species in the formation. In fact there were probably at least 3 or 4 others, obscure but distinct from each other.

The difference in proportions may be explained by the fact that Brachiosaurus and Giraffatitan were from different branches of Brachiosauridae to begin with. And the Archbishop and some of the North American forms (including the shoulder material "ultrasauros" perhaps) belong to yet a third, narrow-bodied branch. And Astrodon/Pleurocoelus, Abydosaurus, and Cedarosaurus, may form yet another branch, which only became common in the Cretaceous.
thedinorocker's avatar
Great work Nima!
Now I am waiting for the updated Giraffatitan (after your blog post about G.brancai dorsals).

Ps- Can I have your e-mail adress to send you "my" M.sinocanadorum (it s finished)?
Paleo-King's avatar
Yes. It's

Thanks! I'm updating both Giraffatitan and Lusotitan. Giraffatitan is planned to be a multi-view. And yes the dorsals are even steeper than before. This animal was so steep the only logical conclusion is a vertical neck.
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