This is the Jurassic World Legacy Collection Brachiosaurus. I think it might be an exclusive at Target stores here in the US. It turns up on other sites, like Amazon and eBay, but usually from 3rd-party sellers and with a healthy up-charge. Retails for 50 bucks. I got mine for Christmas from Vicki and London. Here’s the link to Target.com if you want to check it out (we get no kickbacks from this).

I thought it would be cool to leverage this thing at outreach events to talk about the new Brachiosaurus humerus that Brian Engh found last year, which a team of us got out of the ground and safely into a museum last October (full story here). But I needed a Brachiosaurus humerus, so I made one, and in this post I’ll show you how to do the same, for next to no money.

Depending on what base you start with and what materials you use, you could build a scale model of a Brachiosaurus humerus at any size. I wanted one that would match the JWLC Brach, so I started by taking some measurements of that. Here’s what I got:

Lengths

  • Head: 45mm
  • Neck: 455mm (x 20 = 9.1m = 29’10”)
  • Torso: 320mm
  • Tail: 320mm
  • Total: 1140 (x 20 = 22.8m = 74’10”)

Heights

  • Max head height: 705mm (x 20 = 14.1m = 46’3″)
  • Withers height: 360mm (x 20 = 7.2m = 23’7″)

The neck length, total length, and head height are pretty close to the mounted Giraffatitan in Berlin. The withers are a little high, as is the bottom of the animal’s belly. I suspect that the limbs on the model are oversized by about 10%. Nevertheless, the numbers say this thing is roughly 1/20 scale.

The largest humeri of Brachiosaurus and Giraffatitan are 213cm, which is about 3mm shy of 7 feet. So a 1/20 scale humerus should be 106.5mm, or 4.2 inches, or four-and-a-quarter if you want a nice, round number.

Incidentally, Chris Pratt is 6’2″ (74 inches), and the Owen Grady action figure is 3.75″, which is 1/20 of 6’3″. So the action figure, the Brachiosaurus toy highly detailed scientific model, and a ~4.2″ humerus model will all be more or less in scale with each other.

I used a chicken humerus for my base. The vast majority of chickens in the US are slaughtered at 5 months, so they don’t get nearly big enough for their humeri to be useful for this project. Fortunately, there’s a pub in downtown Claremont, Heroes & Legends, that has giant mutant chicken hot wings, so I went there and collected chicken bones in the guise of a date. The photo above shows three right humeri (on the left) and one left humerus (on the right) after simmering and an overnight degreasing in a pot of soapy water. I used the same bone clean-up methods as in this post.

What should you do if you don’t have access to giant mutant chicken wings? My method of Brachio-mimicry involves some sculpting, so any reasonably straight bone that bells out a bit at the ends would work. You could use a drumstick in a pinch. Here are my humeri whitening in a tub of 3% hydrogen peroxide from the dollar store down the street.

Brachiosaurid humeri vary somewhat but they all have certain features in common. Here’s the right humerus of Vouivria, modified from Mannion et al. (2017: fig. 19) to show the features of interest to brachiosaur humerus-sculptors. The arrows on the far left point to a couple of corners, one where the deltopectoral crest (dpc in the figure) meets the proximal articular surface, and the other where the articular surface meets the long sweeping curve of the medial border of the humeral shaft.

Here’s a more printer-friendly version of the same diagram. Why did I use Vouivria for this instead of one of the humeri of Brachiosaurus itself? Mostly because it’s a complete humerus for which a nice multi-view was available. Runner-up in this category would have to go to the humerus of Pelorosaurus conybeari figured by Upchurch et al. (2015: fig. 18) in the Haestasaurus paper–here’s a direct link to that figure.

I knew that I’d be doing some sculpting, and I wanted a scale template to work off of, so I made these outlines from the Giraffatitan humerus figured by Janensch (1950) and reproduced by Mike in this post (middle two), and from the aforementioned Pelorosaurus conybeari humerus shown by Mike in this post (outer two). I scaled this diagram so that when printed to fill an 8.5×11 piece of printer paper, the humerus outlines would all be 4.25″–the same nice-round-number 1/20 scale target found above. Here’s a PDF version: Giraffatitan and Pelorosaurus humeri outlines for print.

Here’s the largest of my giant mutant chicken humeri, compared to the outlines. The chicken humerus isn’t bad, but it’s too short for 1/20 scale, the angles of the proximal and distal ends are almost opposite what they should be, and the deltopectoral crest is aimed out antero-laterally instead of facing straight anteriorly. Modification will be required!

Here’s my method for lengthing the humerus: I cut the midshaft of another humerus out, and swapped it in to the middle of the prospective Brachiosaurus model humerus.

To my immense irritation, I failed to get a photo of the lengthened humerus before I started sculpting on it. In the first wave of sculpting, I built up the proximal end and the deltopectoral crest, but missed some key features. On the right, I glued the proximal and distal ends of the donor humerus together; I might make this into a Haestasaurus humerus in the future.

I should mention my tools and materials. I have a Dremel but it wasn’t charged the evening I sat down to do this, so I made all the humerus cuts with a small, cheap hacksaw. I used superglue (cyanoacrylate or CA) for quick joins, and white glue (polyvinyl acetate or PVA) to patch holes, and I put gobs of PVA into the humeral shafts before sealing them up. For additive sculpting I used spackling compound, same stuff you use to patch holes in walls and ceilings, and for reductive sculpting I used sandpaper. I got most of this stuff from the dollar store.

Here we are after a second round of sculpting. The proximal end has its corners now, and the distal end is more accurately belled out, maybe even a bit too wide. It’s not a perfect replica of either the Giraffatitan or Pelorosaurus humeri, but it got sufficiently into the brachiosaurid humerus morphospace for my taste. A more patient or dedicated sculptor could probably make recognizable humeri for each brachiosaurid taxon or even specimen. I deliberately left it a bit rough in hopes that it would read as timeworn, fractured, and restored when painted and mounted. Again, a real sculptor could make some hay here by putting in fake cracks and so on.

The cheap spackling compound I picked up did not harden as much as some other I have used in the past. I had planned on sealing anyway before I painted, and for porous materials a quick, cheap sealant is white glue mixed with water. Here that coat of diluted PVA is drying, and I’m holding up a spare chicken humerus to show how far the model humerus has come.

Before painting, I drilled into the distal end with a handheld electric drill, and used a bamboo barbeque skewer as a mounting rod and handle. I hit it with a couple of coats of gray primer, then a couple of coats of black primer the next day. I could have gotten fancier with highlights and washes and so on, but I was scrambling to get this done for a public outreach event, in an already busy week.

And here’s the finished-for-now product. A couple of gold-finished cardboard gift boxes from my spare box storage gave their lids to make a temporary pedestal. When I get a version of this model that I’m really happy with, either by hacking further on this one or starting from scratch on a second, I’d love to get a wooden or stone trophy base with a little engraved plaque that looks like a proper museum exhibit, and replace the bamboo skewer with a brass rod. But for now, I’m pretty happy with this.

The idea of making dinosaurs out of chicken bones isn’t original with me. I was inspired by the wonderful books Make Your Own Dinosaur Out of Chicken Bones and T-Rex To Go, both by Chris McGowan. Used copies of both books can be had online for next to nothing, and I highly recommend them both.

If this post helps you in making your own model Brachiosaurus humerus, I’d love to see the results. Please let me know about your model in the comments, and happy building!

References

  • Janensch, Werner. 1950. Die Wirbelsaule von Brachiosaurus brancai. Palaeontographica (Suppl. 7) 3: 27-93.
  • Mannion PD, Allain R, Moine O. (2017The earliest known titanosauriform sauropod dinosaur and the evolution of BrachiosauridaePeerJ 5:e3217 https://doi.org/10.7717/peerj.3217
  • Upchurch, Paul, Philip D. Mannion and Micahel P Taylor. 2015. The Anatomy and Phylogenetic Relationships of “Pelorosaurus” becklesii (Neosauropoda, Macronaria) from the Early Cretaceous of England. PLoS ONE 10(6):e0125819. doi:10.1371/journal.pone.0125819

On today’s episode of the I Know Dino postcast, Garret interviews Brian and me about our new Brachiosaurus bones and how we got them out of the field. You should listen to the whole thing, but we’re on from 10:10 to 48:15. Here’s the link, go have fun. Many thanks to the I Know Dino crew for their interest, and to Garret for being such a patient and accommodating host. Amazingly, there is a much longer version of the interview available for I Know Dino Patreon supporters, so check that out for more Brachiosaurus yap than you are probably prepared for.

The photo is an overhead shot of me, Casey Cordes, and Yara Haridy smoothing down a plaster wrap around the middle of humerus. The 2x4s aren’t on yet, and the sun is low, so this must have been in the late afternoon on our first day in the quarry in October. Photo by Brian Engh, who perched up on top of the boulder next to the bone to get this shot.

For the context of the Brach-straction, see Part 1 of Jurassic Reimagined on Brian’s paleoart YouTube channel, and stay tuned for more.

FHPR 17108, a right humerus of Brachiosaurus, with Wes Bartlett and his Clydesdale Molly for scale. Original paleoart by Brian Engh.

Last May I was out in the Salt Wash member of the Morrison Formation with Brian Engh and Thuat Tran, for just a couple of days of prospecting. We’d had crappy weather, with rain and lots of gnats. But temperatures were cooler than usual, and we were able to push farther south in our field area than ever before. We found a small canyon that had bone coming out all over, and as I was logging another specimen in my field book, I heard Brian shout from a few meters away: “Hey Matt, I think you better get over here! If this is what I think it is…”

What Brian had found–and what I couldn’t yet show you when I put up this teaser post last month–was this:

That’s the proximal end of a Brachiosaurus humerus in the foreground, pretty much as it was when Brian found it. Thuat Tran is carefully uncovering the distal end, some distance in the background.

Here’s another view, just a few minutes later:

After uncovering both ends and confirming that the proximal end was thin, therefore a humerus (because of its shape), and therefore a brachiosaur (because of its shape and size together), we were elated, but also concerned. This humerus–one of the largest ever found–was lying in what looked like loose dirt, actually sitting in a little fan of sediment cascading down into the gulch. We knew we needed to get it out before the winter rains came and destroyed it. And for that, we’d need John Foster’s experience with getting big jackets out of inconvenient places. We were also working out there under the auspices of John’s permit, so for many reasons we needed him to see this thing.

We managed to all rendezvous at the site in June: Brian, John, ReBecca Hunt-Foster, their kids Ruby and Harrison, and Thuat. We uncovered the whole bone from stem to stern and put on a coat of glue to conserve it. Any doubts we might have had about the ID were dispelled: it was a right humerus of Brachiosaurus.

While we were waiting for the glue to dry, Brian and Ruby started brushing of a hand-sized bit of bone showing just a few feet away. After about an hour, they had extracted the chunk of bone shown above. This proved to be something particularly exciting: the proximal end of the matching left humerus. We hiked that chunk out, along with more chunks of bone that were tumbled down the wash, which may be pieces of the shaft of the second humerus.

But we still had the intact humerus to deal with. We covered it with a tarp, dirt, and rocks, and started scheming in earnest on when, and more importantly how, to get it out. It weighed hundreds of pounds, and it was halfway down the steep slope of the canyon, a long way over broken ground from even the unmaintained jeep trail that was the closest road. Oh, and there are endangered plants in the area, so we coulnd’t just bulldoze a path to the canyon. We’d have to be more creative.

I told a few close friends about our find over the summer, and my standard line was that it was a very good problem to have, but it was actually still a problem, and one which we needed to solve before the winter rains came.

As it happened, we didn’t get back out to the site until mid-October, which was pushing it a bit. The days were short, and it was cold, but we had sunny weather, and we managed to get the intact humerus uncovered and top-jacketed. Here John Foster and ReBecca Hunt-Foster are working on a tunnel under the bone, to pass strips of plastered canvas through and strengthen the jacket. Tom Howells, a volunteer from the Utah Field House in Vernal, stands over the jacket and assists. Yara Haridy was also heavily involved with the excavation and jacketing, and Brian mixed most of the plaster himself.

John Foster, Brian Engh, Wes and Thayne Bartlett, and Matt Wedel (kneeling). Casey Cordes (blue cap) is in the foreground, working the winch. Photo courtesy of Brian Engh.

Here we go for the flip. The cable and winch were rigged by Brian’s friend, Casey Cordes, who had joined us from California with his girlfriend, teacher and photographer Mallerie Niemann.

Photo courtesy of Brian Engh.

Jacket-flipping is always a fraught process, but this one went smooth as silk. As we started working down the matrix to slim the jacket, we uncovered a few patches of bone, and they were all in great shape.

So how’d we get this monster out of the field?

From left to right: Wes Bartlett and one of his horses, Matt Wedel, Tom Howells, and Thayne Bartlett. Photo by Brian Engh.

Clydesdales! John had hired the Bartlett family of Naples, Utah–Wes, Resha, and their kids Thayne, Jayleigh, Kaler, and Cobin–who joined us with their horses Molly and Darla. Brian had purchased a wagon with pneumatic tires from Gorilla Carts. Casey took the point on winching the jacket down to the bottom of the wash, where we wrestled it onto the wagon. From there, one of the Clydesdales took it farther down the canyon, to a point where the canyon wall was shallow enough that we could get the wagon up the slope and out. The canyon slope was slickrock, not safe for the horses to pull a load over, so we had to do that stretch with winches and human power, mostly Brian, Tom, and Thayne pushing, me steering, and Casey on the winch.

Easily the most epic and inspiring photo of my butt ever taken. Wes handles horses, Casey coils rope, Thayne pushes the cart, and Kaler looks on. Photo by Brian Engh.

Up top, Wes hooked up the other horse to pull the wagon to the jeep trail, and then both horses to haul the jacket out to the road on a sled. I missed that part–I had gone back to the quarry to grab tools before it got dark–but Brian got the whole thing on video, and it will be coming soon as part of his Jurassic Reimagined documentary series.

There’s one more bit I have to tell, but I have no photos of it: getting the jacket off the sled and onto the trailer that John had brought from the Field House. We tried winching, prybar, you name it. The thing. Just. Did. Not. Want. To. Move. Then Yara, who is originally from Egypt, said, “You know, when my people were building the pyramids, we used round sticks under the big blocks.” As luck would have it, I’d brought about a meter-long chunk of thick dowel from my scrap wood bin. Brian used a big knife to cut down some square posts into roughly-round shapes, and with those rollers, the winch, and the prybar, we finally got the jacket onto the trailer.

The real heroes of the story are Molly and Darla. In general, anything that the horses could help with went waaay faster and more smoothly than we expected, and anything we couldn’t use the horses for was difficult, complex, and terrifying. I’d been around horses before, but I’d never been up close and personal with Clydesdales, and it was awesome. As someone who spends most of his time thinking about big critters, it was deeply satisfying to use two very large animals to pull out a piece of a truly titanic animal.

Back in the prep lab at the Field House in Vernal: Matt Wedel, Brian Engh, Yara Haridy, ReBecca Hunt-Foster, and John Foster.

We’re telling the story now because the humerus is being unveiled for the public today at the Utah Field House of Natural History State Park Museum in Vernal. The event will be at 11:00 AM Mountain Time, and it is open to the public. The humerus, now cataloged as FHPR 17108, will be visible to museum visitors for the rest of its time in the prep lab, before it eventually goes on display at the Field House. We’re also hoping to use the intact right humerus as a Rosetta Stone to interpet and piece back together the shattered chunks of the matching left humerus. There will be a paper along in due time, but obviously some parts of the description will have to wait until the right humerus is fully prepped, and we’ve made whatever progress we can reconstructing the left one.

Why is this find exciting? For a few reasons. Despite its iconic status, in dinosaur books and movies like Jurassic Park, Brachiosaurus is actually a pretty rare sauropod, and as this short video by Brian Engh shows, much of the skeleton is unknown (for an earlier, static image that shows this, see Mike’s 2009 paper on Brachiosaurus and Giraffatitan, here). Camarasaurus is known from over 200 individuals, Apatosaurus and Diplodocus from over 100 individuals apiece, but Brachiosaurus is only known from about 10. So any new specimens are important.

A member of the Riggs field crew in 1900, lying next to the humerus of the holotype specimen of Brachiosaurus. I’m proud to say that I know what this feels like now!

If Brachiosaurus is rare, Brachiosaurus humeri are exceptionally rare. Only two have ever been described. The first one, above, is part of the holotype skeleton of Brachiosaurus, FMNH P25107, which came out of the ground near Fruita, Colorado, in 1900, and was described by Elmer S. Riggs in his 1903 and 1904 papers. The second, in the photo below, is the Potter Creek humerus, which was excavated from western Colorado in 1955 but not described until 1987, by Jim Jensen. That humerus, USNM 21903, resides at the National Museum of Natural History in Washington, D.C.

The Brachiosaurus humerus from Potter Creek, Colorado, on display at the Smithsonian.

For the sake of completeness, I have to mention that there is a humerus on display at the LA County Museum of Natural History that is labeled Brachiosaurus, but it’s not been written up yet, and after showing photos of it to colleagues, I’m not 100% certain that it’s Brachiosaurus (I’m not certain that it isn’t, either, but further study is needed). And there’s at least one humerus with a skeleton that was excavated by the University of Kansas and sold by the quarry owner to a museum in Korea (I had originally misunderstood this; some but not all of the material from that quarry went to KU), that is allegedly Brachiosaurus, but that one seems to have fallen into a scientific black hole. I can’t say anything about its identification because I haven’t seen the material.

Happy and relieved folks the morning after the Brachstraction: Yara Haridy, Matt Wedel, John and Ruby Foster, and the Bartletts: Kaler, Wes, Cobin, Resha, Jayleigh, and Thayne. Jacketed Brachiosaurus humerus for scale. Photo by Brian Engh.

So our pair of humeri from the Salt Wash of Utah are only the 3rd and 4th that I can confidently say are from Brachiosaurus. And they’re big. Both are at least 62cm wide across the proximal end, and the complete one is 201cm long. To put that into context, here’s a list of the longest sauropod humeri ever found:

  1. Brachiosaurus, Potter Creek, Colorado: 213cm
  2. Giraffatitan, MB.R.2181/SII specimen, Tanzania: 213cm
  3. Brachiosaurus, holotype, Colorado: ~213cm (preserved length is 203cm, but the distal end is eroded, and it was probably 213cm when complete)
  4. Giraffatitan, XV3 specimen, Tanzania: 210cm
  5. *** NEW Brachiosaurus, FHPR 17108, Utah: 201cm
  6. Ruyangosaurus (titanosaur from China): ~190cm (estimated from 135cm partial)
  7. Turiasaurus (primitive sauropod from Spain): 179cm
  8. Notocolossus (titanosaur from Argentina): 176cm
  9. Paralititan (titanosaur from Egypt): 169cm
  10. Patagotitan (titanosaur from Argentina): 167.5cm
  11. Dreadnoughtus (titanosaur from Argentina): 160cm
  12. Futalognkosaurus (titanosaur from Argentina): 156cm

As far as we know, our intact humerus is the 5th largest ever found on Earth. It’s also pretty complete. The holotype humerus has an eroded distal end, and was almost certainly a few centimeters longer in life. The Potter Creek humerus was missing the cortical bone from most of the front of the shaft when it was found, and has been heavily restored for display, as you can see in one of the photos above. Ours seems to have both the shaft and the distal end intact. The proximal end has been through some freeze-thaw cycles and was flaking apart when we found it, but the outline is pretty good. Obviously a full accounting will have to wait until the bone is fully prepared, but we might just have the best-preserved Brachiosaurus humerus yet found.

Me with a cast of the Potter Creek humerus in the collections at Dinosaur Journey in Fruita, Colorado. The mold for this was made from the original specimen before it was restored, so it’s missing most of the bone from the front of the shaft. Our new humerus is just a few cm shorter. Photo by Yara Haridy.

Oh, our Brachiosaurus is by far the westernmost occurrence of the genus so far, and the stratigraphically lowest, so it extends our knowledge of Brachiosaurus in both time and space. It’s part of a diverse dinosaur fauna that we’re documenting in the Salt Wash, that minimally also includes Haplocanthosaurus, Camarasaurus, and either Apatosaurus or Brontosaurus, just among sauropods. There are also some exciting non-sauropods in the fauna, which we’ll be revealing very soon.

A chunk of matrix from the brachiosaur quarry. The black bits are fossilized plants.

And that’s not all. Unlike most of the other dinosaur fossils we’ve found in the Salt Wash, including the camarasaur, apatosaur, and haplocanthosaur vertebrae I’ve shown in recent posts, the humeri were not in concrete-like sandstone. Instead, they came out of a sandy clay layer, and the matrix is packed with plant fossils. It was actually kind of a pain during the excavation, because I kept getting distracted by all the plants. We did manage to collect a couple of buckets of the better-looking stuff as we were getting the humerus out, and we’ll be going back for more.

As you can seen in Part 1 of Brian’s Jurassic Reimagined documentary series, we’re not out there headhunting dinosaurs, we’re trying to understand the whole environment: the dinosaurs, the plants, the depositional system, the boom-and-bust cycles of rain and drought–in short, the whole shebang. So the plant fossils are almost as exciting for us as the brachiosaur, because they’ll tell us more about the world of the early Morrison.

The Barletts: Thayne, Jayleigh, Resha, Cobin, Wes, and Kaler.

Among the folks I have to thank, top honors go to the Bartlett family. They came to work, they worked hard, and they were cheerful and enthusiastic through the whole process. Even the kids worked–Thayne was one of the driving forces keeping the wagon moving down the gulch, and the younger Bartletts helped Ruby uncover and jacket a couple of small bits of bone that were in the way of the humerus flip. So Wes, Resha, Thayne, Jayleigh, Kaler, and Cobin: thank you, sincerely. We couldn’t have done it without you all, and Molly and Darla!

EDIT: I also need to thank Casey Cordes–without his rope and winch skills, the jacket would still be out in the desert. And actually everyone on the team was clutch. We had no extraneous human beings and no unused gear. It was a true team effort.

The full version of the art shown at the top of this post: a new life restoration of Brachiosaurus by Brian Engh.

From start to end, this has been a Brian Engh joint. He found the humerus in the first place, and he was there for every step along the way, including creating the original paleoart that I’ve used to bookend this post. When Brian wasn’t prospecting or digging or plastering (or cooking, he’s a ferociously talented cook) he was filming. He has footage of me walking up to the humerus for the first time last May and being blown away, and he has some truly epic footage of the horses pulling the humerus out for us. All of the good stuff will go into the upcoming installments of Jurassic Reimagined. He bought the wagon and the boat winch with Patreon funds, so if you like this sort of thing–us going into the middle of nowhere, bringing back giant dinosaurs, and making blog posts and videos to explain what we’ve found and why we’re excited–please support Brian’s work (link). Also check out his blog, dontmesswithdinosaurs.com–his announcement about the find is here–and subscribe to his YouTube channel, Brian Engh Paleoart (link), for the rest of Jurassic Reimagined and many more documentaries to come.

(SV-POW! also has a Patreon page [link], and if you support us, Mike and I will put those funds to use researching and blogging about sauropods. Thanks for your consideration!)

The happiest I have ever been in the field. Photo by Yara Haridy.

And for me? It’s been the adventure of a lifetime, by turns terrifying and exhilarating. I missed out on the digs where Sauroposeidon, Brontomerus, and Aquilops came out of the ground, so this is by far the coolest thing I’ve been involved with finding and excavating. I got to work with old friends, and I made new friends along the way. And there’s more waiting for us, in “Brachiosaur Gulch” and in the Salt Wash more generally. After five years of fieldwork, we’ve just scratched the surface. Watch this space!

Media Coverage

Just as I was about to hit ‘publish’ I learned that this story has been beautifully covered by Anna Salleh of the Australian Broadcasting Corporation. I will add more links as they become available.

References

Arm lizard

December 16, 2019

Reconstructed right forelimb of Brachiosaurus at Dinosaur Journey in Fruita, Colorado, with me for scale, photo by Yara Haridy. The humerus is a cast of the element from the holotype skeleton, FMNH P25107, the coracoid looks like a sculpt to match the coracoid from the holotype (which is a left), and the other elements are either cast or sculpted from Giraffatitan. But it’s all approximately correct. The actual humerus is 204cm long, but the distal end is eroded and it was probably 10-12cm longer in life. I don’t know how big this cast is, but I know that casts are inherently untrustworthy so I suspect it’s a few cm shorter than it oughta be. For reference, I’m 188cm, but I’m standing a bit forward of the mount so I’m an imperfect scale bar (like all scale bars!). For another view of the same mount from five years ago, see this post.

So I guess the moral is that even thought this reconstructed forelimb looks impressive, the humerus was several inches longer, even before we account for any shrinkage in the molding and casting process, and the gaps between the bones for joint cartilage should probably be much wider, so the actual shoulder height of this individual might have been something like a foot taller than this mount. A mount, by the way, that is about as good as it could practically be, and which I love — I’m including all the caveats and such partly because I’m an arch-pedant, and partly because it’s genuinely useful to know all the ways in which a museum mount might be subtly warping the truth, especially if you’re interested in the biggest of the big.

All of which is a long walk to the conclusion that brachiosaurs are pretty awesome. More on that real soon now. Stay tuned.

Here are the humerus and ulna of a pelican, bisected:

What we’re seeing here is the top third of each bone: humerus halves on the left, ulna halves on the right, in a photo taken at the 2012 SVPCA in one of our favourite museums.

The hot news here is of course the extreme pneumaticity: the very thin bone walls, reinforced only at the proximal extremely by thin struts. Here’s the middle third, where as you can see there is essentially no reinforcement: just a hollow tube, that’s all:

And then at the distal ends, we see the struts return:

Here’s the whole thing in a single photo, though unfortunately marred by a reflection (and obviously at much lower resolution):

We’ve mentioned before that pelicans are crazy pneumatic, even by the standards of other birds: as Matt said about a pelican vertebra (skip to 58 seconds in the linked video), “the neural spine is sort of a fiction, almost like a tent of bone propped up”.

Honestly. Pelican skeletons hardly even exist.

Notocolossus is a beast

January 20, 2016

Notocolossus skeletal recon - Gonzalez Riga et al 2016 fig 1

(a) Type locality of Notocolossus (indicated by star) in southern-most Mendoza Province, Argentina. (b) Reconstructed skeleton and body silhouette in right lateral view, with preserved elements of the holotype (UNCUYO-LD 301) in light green and those of the referred specimen (UNCUYO-LD 302) in orange. Scale bar, 1 m. (González Riga et al. 2016: figure 1)

This will be all too short, but I can’t let the publication of a new giant sauropod pass unremarked. Yesterday Bernardo González Riga and colleagues published a nice, detailed paper describing Notocolossus gonzalezparejasi, “Dr. Jorge González Parejas’s southern giant”, a new titanosaur from the Late Cretaceous of Mendoza Province, Argentina (González Riga et al. 2016). The paper is open access and freely available to the world.

As you can see from the skeletal recon, there’s not a ton of material known from Notocolossus, but among giant sauropods it’s actually not bad, being better represented than Argentinosaurus, Puertasaurus, Argyrosaurus, and Paralititan. In particular, one hindfoot is complete and articulated, and a good chunk of the paper and supplementary info are devoted to describing how weird it is.

But let’s not kid ourselves – you’re not here for feet, unless it’s to ask how many feet long this monster was. So how big was Notocolossus, really?

Well, it wasn’t the world’s largest sauropod. And to their credit, no-one on the team that described it has made any such superlative claims for the animal. Instead they describe it as, “one of the largest terrestrial vertebrates ever discovered”, and that’s perfectly accurate.

Notocolossus limb bones - Gonzalez Riga et al 2016 fig 4

(a) Right humerus of the holotype (UNCUYO-LD 301) in anterior view. Proximal end of the left pubis of the holotype (UNCUYO-LD 301) in lateral (b) and proximal (c) views. Right tarsus and pes of the referred specimen (UNCUYO-LD 302) in (d) proximal (articulated, metatarsus only, dorsal [=anterior] to top), (e) dorsomedial (articulated), and (f) dorsal (disarticulated) views. Abbreviations: I–V, metatarsal/digit number; 1–2, phalanx number; ast, astragalus; cbf, coracobrachialis fossa; dpc, deltopectoral crest; hh, humeral head; ilped, iliac peduncle; of, obturator foramen; plp, proximolateral process; pmp, proximomedial process; rac, radial condyle; ulc, ulnar condyle. Scale bars, 20 cm (a–c), 10 cm (d–f). (Gonzalez Riga et al 2016: figure 4)

Any discussions of the size of Notocolossus will be driven by one of two elements: the humerus and the anterior dorsal vertebra. The humerus is 176 cm long, which is shorter than those of Giraffatitan (213 cm), Brachiosaurus (204 cm), and Turiasaurus (179 cm), but longer than those of Paralititan (169 cm), Dreadnoughtus (160 cm), and Futalognkosaurus (156 cm). Of course we don’t have a humerus for Argentinosaurus or Puertasaurus, but based on the 250-cm femur of Argentinosaurus, the humerus was probably somewhere around 200 cm. Hold that thought.

Notocolossus and Puertasaurus dorsals compared

Top row: my attempt at a symmetrical Notocolossus dorsal, made by mirroring the left half of the fossil from the next row down. Second row: photos of the Notocolossus dorsal with missing bits outlined, from Gonzalez Riga et al (2016: fig. 2). Scale bar is 20 cm (in original). Third row: the only known dorsal vertebra of Puertasaurus, scaled to about the same size as the Notocolossus vertebra, from Novas et al. (2005: fig. 2).

The anterior dorsal tells a similar story, and this is where I have to give González Riga et al. some props for publishing such detailed sets of measurements in the their supplementary information. They Measured Their Damned Dinosaur. The dorsal has a preserved height of 75 cm – it’s missing the tip of the neural spine and would have been a few cm taller in life – and by measuring the one complete transverse process and doubling it, the authors estimate that when complete it would have been 150 cm wide. That is 59 inches, almost 5 feet. The only wider vertebra I know of is the anterior dorsal of Puertasaurus, at a staggering 168 cm wide (Novas et al. 2005). The Puertasaurus dorsal is also quite a bit taller dorsoventrally, at 106 cm, and it has a considerably larger centrum: 43 x 60 cm, compared to 34 x 43.5 cm for Notocolossus (anterior centrum diameters, height x width).

Centrum size is an interesting parameter. Because centra are so rarely circular, arguably the best way to compare across taxa would be to measure the max area (or, since centrum ends are also rarely flat, the max cross-sectional area). It’s late and this post is already too long, so I’m not going to do that now. But I have been keeping an informal list of the largest centrum diameters among sauropods – and, therefore, among all Terran life – and here they are (please let me know if I missed anyone):

  • 60 cm – Argentinosaurus dorsal, MCF-PVPH-1, Bonaparte and Coria (1993)
  • 60 cm – Puertasaurus dorsal, MPM 10002, Novas et al. (2005)
  • 51 cm – Ruyangosaurus cervical and dorsal, 41HIII-0002, Lu et al. (2009)
  • 50 cm – Alamosaurus cervical, SMP VP−1850, Fowler and Sullivan (2011)
  • 49 cm – Apatosaurus ?caudal, OMNH 1331 (pers. obs.)
  • 49 cm – Supersaurus dorsal, BYU uncatalogued (pers. obs.)
  • 46 cm – Dreadnoughtus dorsal, MPM-PV 1156, Lacovara et al. (2014: Supplmentary Table 1) – thanks to Shahen for catching this one in the comments!
  • 45.6 cm – Giraffatitan presacral, Fund no 8, Janensch (1950: p. 39)
  • 45 cm – Futalognkosaurus sacral, MUCPv-323, Calvo et al. (2007)
  • 43.5 cm – Notocolossus dorsal, UNCUYO-LD 301, González Riga et al. (2016)

(Fine print: I’m only logging each taxon once, by its largest vertebra, and I’m not counting the dorsoventrally squashed Giraffatitan cervicals which get up to 47 cm wide, and the “uncatalogued” Supersaurus dorsal is one I saw back in 2005 – it almost certainly has been catalogued in the interim.) Two things impress me about this list: first, it’s not all ‘exotic’ weirdos – look at the giant Oklahoma Apatosaurus hanging out halfway down the list. Second, Argentinosaurus and Puertasaurus pretty much destroy everyone else by a wide margin. Notocolossus doesn’t seem so impressive in this list, but it’s worth remembering that the “max” centrum diameter here is from one vertebra, which was likely not the largest in the series – then again, the same is true for Puertasaurus, Alamosaurus, and many others.

Notocolossus phylogeny - Gonzalez Riga et al 2016 fig 5

(a) Time-calibrated hypothesis of phylogenetic relationships of Notocolossus with relevant clades labelled. Depicted topology is that of the single most parsimonious tree of 720 steps in length (Consistency Index = 0.52; Retention Index = 0.65). Stratigraphic ranges (indicated by coloured bars) for most taxa follow Lacovara et al.4: fig. 3 and references therein. Additional age sources are as follows: Apatosaurus[55], Cedarosaurus[58], Diamantinasaurus[59], Diplodocus[35], Europasaurus[35], Ligabuesaurus[35], Neuquensaurus[60], Omeisaurus[55], Saltasaurus[60], Shunosaurus[55], Trigonosaurus[35], Venenosaurus[58], Wintonotitan[59]. Stratigraphic ranges are colour-coded to also indicate geographic provenance of each taxon: Africa (excluding Madagascar), light blue; Asia (excluding India), red; Australia, purple; Europe, light green; India, dark green; Madagascar, dark blue; North America, yellow; South America, orange. (b–h) Drawings of articulated or closely associated sauropod right pedes in dorsal (=anterior) view, with respective pedal phalangeal formulae and total number of phalanges per pes provided (the latter in parentheses). (b) Shunosaurus (ZDM T5402, reversed and redrawn from Zhang[45]); (c) Apatosaurus (CM 89); (d) Camarasaurus (USNM 13786); (e) Cedarosaurus (FMNH PR 977, reversed from D’Emic[32]); (f) Epachthosaurus (UNPSJB-PV 920, redrawn and modified from Martínez et al.[22]); (g) Notocolossus; (h) Opisthocoelicaudia (ZPAL MgD-I-48). Note near-progressive decrease in total number of pedal phalanges and trend toward phalangeal reduction on pedal digits II–V throughout sauropod evolutionary history (culminating in phalangeal formula of 2-2-2-1-0 [seven total phalanges per pes] in the latest Cretaceous derived titanosaur Opisthocoelicaudia). Abbreviation: Mya, million years ago. Institutional abbreviations see Supplementary Information. (González Riga et al. 2016: figure 5)

As for the estimated mass of Notocolossus, González Riga et al. (2016) did their due diligence. The sections on mass estimation in the main text and supplementary information are very well done – lucid, modest, and fair. Rather than try to summarize the good bit, I’ll just quote it. Here you go, from page 7 of the main text:

The [humeral] diaphysis is elliptical in cross-section, with its long axis oriented mediolaterally, and measures 770 mm in minimum circumference. Based on that figure, the consistent relationship between humeral and femoral shaft circumference in associated titanosaurian skeletons that preserve both of these dimensions permits an estimate of the circumference of the missing femur of UNCUYO-LD 301 at 936 mm (see Supplementary Information). (Note, however, that the dataset that is the source of this estimate does not include many gigantic titanosaurs, such as Argentinosaurus[5], Paralititan[16], and Puertasaurus[11], since no specimens that preserve an associated humerus and femur are known for these taxa.) In turn, using a scaling equation proposed by Campione and Evans[20], the combined circumferences of the Notocolossus stylopodial elements generate a mean estimated body mass of ~60.4 metric tons, which exceeds the ~59.3 and ~38.1 metric ton masses estimated for the giant titanosaurs Dreadnoughtus and Futalognkosaurus, respectively, using the same equation (see Supplementary Information). It is important to note, however, that subtracting the mean percent prediction error of this equation (25.6% of calculated mass[20]) yields a substantially lower estimate of ~44.9 metric tons for UNCUYO-LD 301. Furthermore, Bates et al.[21] recently used a volumetric method to propose a revised maximum mass of ~38.2 metric tons for Dreadnoughtus, which suggests that the Campione and Evans[20] equation may substantially overestimate the masses of large sauropods, particularly giant titanosaurs. Unfortunately, however, the incompleteness of the Notocolossus specimens prohibits the construction of a well-supported volumetric model of this taxon, and therefore precludes the application of the Bates et al.[21] method. The discrepancies in mass estimation produced by the Campione and Evans[20] and Bates et al.[21] methods indicate a need to compare the predictions of these methods across a broad range of terrestrial tetrapod taxa[21]. Nevertheless, even if the body mass of the Notocolossus holotype was closer to 40 than 60 metric tons, this, coupled with the linear dimensions of its skeletal elements, would still suggest that it represents one of the largest land animals yet discovered.

So, nice work all around. As always, I hope we get more of this critter someday, but until then, González Riga et al. (2016) have done a bang-up job describing the specimens they have. Both the paper and the supplementary information will reward a thorough read-through, and they’re free, so go have fun.

References

Well, who knew? There I was posting images of “Pelorosaurusbecklesi‘s humerus, radius and ulna, and skin impression. There I was saying that this beast is due a proper description, and warrants its own generic name. And what should come out today but a new paper by Paul Upchurch, Phil Mannion and, oh yes, me, which does exactly that.

Screen Shot 2015-06-03 at 19.05.12

The headline news is the long-overdue establishment of a new genus name for this species — something that we’ve known was needed at least since Upchurch’s (1993) dissertation. Paul and Phil came up with the name Haestasaurus, from “Haesta”, the name of the putative pre-Roman chieftain whose people apparently settled the area of Hastings and gave the town its name. It’s nice that I can finally stop typing the scare-quotes around the no-longer-relevant old genus name “Pelorosaurus“!

Upchurch et al. 2015: figure 2. Left humerus of Haestasaurus becklesii (NHMUK R1870). A, anterior view; B, posterior view; Abbreviations: af, anconeal fossa; dp, deltopectoral crest; hh, humeral head; ltf, lateral triceps fossa; mtf, medial triceps fossa.

Upchurch et al. (2015: figure 2). Left humerus of Haestasaurus becklesii (NHMUK R1870). A, anterior view; B, posterior view; Abbreviations: af, anconeal fossa; dp, deltopectoral crest; hh, humeral head; ltf, lateral triceps fossa; mtf, medial triceps fossa.

(As you can see, the photography is rather better than in my own illustrations, which I made independently some years ago.)

Of course Paul has had an eye on this work, on and off, since the early 1990s. Then in the late 2000s, when I was working on Xenoposeidon and other Wealden sauropods, I started work independently on a redescription — which of course is why I prepared the figures that have appeared in the last few posts. But that work petered out as I started working more on other specimens and on the problems of the sauropod neck. More recently, Paul and Phil hunkered down and got the nitty-gritty descriptive work done.

Once they had a complete draft manuscript, they very graciously invited me onto the authorship — not something they had to do, but they chose to based on my previous interest in the specimen. My contribution was minor: I provided two of the illustrations, tidied up the early versions of several others, and did an editing pass on the text.

Upchurch et al. (2015: figure 1). Map showing England and Wales, with boundaries for English counties. The magnified inset shows the Isle of Wight and East and West Sussex in more detail, marking the positions of selected major towns/cities and the fossil localities mentioned in the main text. Based on

Upchurch et al. (2015: figure 1). Map showing England and Wales, with boundaries for English counties. The magnified inset shows the Isle of Wight and East and West Sussex in more detail, marking the positions of selected major towns/cities and the fossil localities mentioned in the main text. Based on “English ceremonial counties 1998” by Dr. Greg, http://en.wikipedia.org/wiki/File:English_ceremonial_counties_1998.svg. CC By-SA 3.0.

(This map is one of the two illustrations that I provided; the other is the multi-view photograph of the Pelorosaurus conbeari humerus.)

I’m grateful to Paul and Phil, both for inviting me onto this project, and for taking into account my strong preference for an open-access venue. It’s largely because of the latter that the paper now appears in PLOS ONE, where the glorious colour illustrations appear at full resolution and may be re-used for any purpose subject to attribution.

So: what actually is Haestasaurus? Is it the early titanosaur that we’ve all been assuming? The unexciting answer is: we don’t really know. Our paper contains three phylogenetic hypotheses (all of them Paul and Phil’s work, I can’t take any credit). These results are from adding Haestasaurus to the Carballido and Sander (2014) matrix, to the Mannion et al. (2013) standard discrete matrix and to the Mannion et al. (2013) continuous-and-discrete matrix. Only the last of these recovers Haestasaurus as a titanosaur — as sister to Diamantinasaurus and then Malawisaurus, making it a lithostrotian well down inside Titanosauria.

Both both of the other analyses find Haestasaurus as a very basal macronarian — outside of Titanosauriformes. Here is the result of the analysis based on Carballido and Sander’s Europasaurus matrix:

Upchurch et al. (2105: figure 15). Strict consensus tree (CSM). A strict consensus tree based on the 28 most parsimonious trees generated by analysis of the Carballido and Sander [19] data matrix with the addition of Haestasaurus and six new characters (Tendaguria excluded a priori). GC values (multiplied by 100) are shown in square brackets for all nodes where these values are greater than 0. The monophyletic Diplodocoidea has been collapsed to a single branch in order to reduce figure size. Abbreviation: Brc, Brachiosauridae.

Upchurch et al. (2105: figure 15). Strict consensus tree (CSM). A strict consensus tree based on the 28 most parsimonious trees generated by analysis of the Carballido and Sander [19] data matrix with the addition of Haestasaurus and six new characters (Tendaguria excluded a priori). GC values (multiplied by 100) are shown in square brackets for all nodes where these values are greater than 0. The monophyletic Diplodocoidea has been collapsed to a single branch in order to reduce figure size. Abbreviation: Brc, Brachiosauridae.

As you can see, Haestasaurus is here a camarasaurid, making it (along with Camarasaurus itself) the most basal of all macronarians. In the second analysis — the one using discrete characters only from Mannion et al.’s Lusotitan paper — Haestasaurus is again in the most basal macronarian clade, but this time as sister to Janenschia and then Tehuelchesaurus. (In this topology, Camarasaurus is the next most basal macronarian after that three-taxon clade.)

So it looks like Haestasaurus is either a very basal macronarian or a pretty derived titanosaur. We don’t know which.

But, hey, at least it has a proper name now!

Acknowledgements

It’s Matt’s birthday today. I’d like to dedicate a sauropod to him, but I don’t have the authority to do that. So instead, I dedicate this blog-post to him, and declare it the Mathew J. Wedel Memorial Blog Post.

References

It’s an oddity that in eight years of SV-POW!, we’ve never written about one of the best of all the Wealden-formation sauropod specimens: the forelimb and associated skin impression NHMUK R1870 that is known as “Pelorosaurusbecklesii.

Let’s fix that. Here is all the bony material (i.e. everything except the skin patch) in a photo taken in the basement of the Natural History Museum back in 2007:

Left forelimb material of

Left forelimb material of “Pelorosaurusbecklesii holotype NHMUK R1870. Left: humerus, in posterior view. Right, from top to bottom: ulna in anterior view; radius in anterior view. Yes, I should have turned the humerus over before taking this photo. What can I tell you? I was young and stupid then.

As you can see, the two lower-limb bones were broken back then (though I believe they have since been repaired), but the breaks are very clean, and it’s actually quite interesting to see inside the bones:

Breakage in bones of the lower left forelimb of

Breakage in bones of the lower left forelimb of “Pelorosaurusbecklesii holotype NHMUK R1870. Left: proximal part of radius in distal view. Right: proximal part of ulna in distal view.

I wish I knew enough about mineralisation to comment intelligently on what we can see there. If anyone has thoughts, do leave them in the comments.

We can look in more detail at those lower-limb bones in a subsequent post, but for now, here’s the humerus:

Pelorosaurusbecklesii holotype NHMUK R1870, left humerus. Top row: proximal view, with anterior to the bottom. Middle row, from left to right: medial, anterior, lateral and posterior views. Bottom row: distal view, with anterior to the top.

As you can see it’s in really nice shape, and pretty distinctive. Way back in my 2007 Progressive Palaeo talk (Taylor 2007), I coded up the humerus (alone, without the other elements) in the Harris-based phylogenetic matrix that I’ve used repeatedly in other projects. It came out as the sister taxon to the titanosaur Malawisaurus (which in that matrix comes out fairly basal within Titanosauria): in fact, it could hardly do anything else, since the coding was exactly the same as that of Malawisaurus.

And indeed it’s been pretty widely accepted that “P.” becklesii is a titanosaur — one of the earliest known, and the only name-bearing one from the Wealden Supergroup, unless you count the extremely indeterminate Iuticosaurus, which predictably enough is based on a single eroded partial mid-caudal centrum. Still, the titanosaurian identity of “P.” becklesii has never been convincingly demonstrated — only inferred by non-cladistic means.

Pelorosaurusbecklesii holotype NHMUK R1870, left humerus in anterodistal view (anterior to the left).

So why the quotes around the genus name “Pelorosaurus“? Because it’s long been recognised that, whatever this specimen might be, it ain’t Pelorosaurus, which is based on the Cetiosaurusbrevis caudals and a much more slender humerus.

Here’s that humerus, so you can see how different it is from that of “Pelorosaurusbecklesii:

Right humerus of Pelorosaurus conybeari holotype NHMUK 28626. Top row: distal view, anterior to bottom. Middle row, left to right: lateral, anterior and medial views. Bottom row: distal, anterior to top. Missed parts reconstructed from the humerus of Giraffatitan brancai (Janensch 1961: Beilage A)

Right humerus of Pelorosaurus conybeari holotype NHMUK 28626. Top row: distal view, with anterior to bottom. Middle row, left to right: lateral, anterior and medial views. Bottom row: distal view, with anterior to top. Missing parts reconstructed from the humerus of Giraffatitan brancai (Janensch 1961: Beilage A)

Paul Upchurch recognised the generic distinctness of “Pelorosaurusbecklesii way back in his (1993) dissertation. But because of Cambridge University’s policy of only making copies of dissertations available for £65, that work is effectively unknown. (Perhaps we should all chip in a fiver, buy a copy and “liberate” it. Or maybe 22 years on, Paul would rather leave it in obscurity and let his reputation continue to rest on his impressive body of later work.)

What has happened to this specimen in the last 22 years? Very little has been published about it. It got a mention in the systematic review of sauropods in Dinosauria II (Upchurch et al. 2004), but the only mention that is more than in passing, as far as I’m aware, is that of see Upchurch’s first published (1995) phylogenetic analysis. From page 380:

The only reliable Lower Cretaceous titanosaurid material, apart from Malawisaurus, comes from Europe, especially England. The earliest of these forms may be represented by the forelimb of ‘Pelorosaurus becklesii‘ (Mantell 1852) from the Valanginian of Sussex. This specimen was considered to be Sauropoda incertae sedis by McIntosh (1990b). However, a skin impression shows polygonal plates of a similar shape and size to those found in Saltasaurus (Bonaparte & Powell 1980). The ulna and radius are robust and the ulna bears the typical concavity on its anteromedial proximal process. Upchurch (1993) therefore argued that this form should be provisionally included within the Titanosauridae.

[Update: as Darren points out in the comment below, Upchurch et al. (2011) figure the specimen in colour and devote three pages to it. They leave it as Titanosauria, and “refrain from naming a new taxon until more comparative data are available” (p. 501).]

Given my interest in the Wealden, it’s surprising that we’ve never blogged about “Pelorosaurusbecklesii before, but it’s true: I’ve mentioned it three times in comments, but never in a post. It’s good to finally fix that!

Next time: the radius and ulna.

References

  • Janensch, Werner. 1961. Die Gliedmaszen und Gliedmaszengurtel der Sauropoden der Tendaguru-Schichten. Palaeontographica (Suppl. 7) 3:177-235.
  • Taylor, Michael P. 2007. Diversity of sauropod dinosaurs from the Lower Cretaceous Wealden Supergroup of southern England. p. 23 in Graeme T. Lloyd (ed.), Progressive Palaeontology 2007, Thursday 12th-Saturday 14th April, Department of Earth Sciences, University of Bristol. 38 pp.
  • Upchurch, Paul. 1993. The Anatomy, Phylogeny and Systematics of Sauropod Dinosaurs. Ph.D dissertation, University of Cambridge, UK. 489 pages.
  • Upchurch, Paul. 1995. The evolutionary history of sauropod dinosaurs. Philosophical Transactions of the Royal Society of London Series B, 349:365-390.
  • Upchurch, Paul, Paul M. Barrett and Peter Dodson. 2004. Sauropoda. pp. 259-322 in D. B. Weishampel, P. Dodson and H. Osmólska (eds.), The Dinosauria, 2nd edition. University of California Press, Berkeley and Los Angeles. 861 pages.
  • Upchurch, Paul, Philip D. Mannion and Paul M. Barrett. 2011. Sauropod dinosaurs. pp. 476-525 in: Batten, David J. (ed.), English Wealden Fossils. The Palaeontological Association (London).

Continuing with what seems to have turned out to be Brachiosaur Humerus Week here on SV-POW! (part 1, part 2, part 3), let’s consider the oft-stated idea that brachiosaurs have the most slender humeri of any sauropod. For example, Taylor (2009:796) wrote that:

Discarding a single outlier, the ratio of proximodistal length to minimum transverse width (Gracility Index or GI) in humeri of B. brancai [i.e. Giraffatitan] varies between 7.86 for the right humerus HMN F2 and 9.19 for the left humerus HMN J12, with the type specimen’s right humerus scoring 8.69, slightly more gracile than the middle of the range […] For the B. altithorax type specimen, the GI is 8.50, based on the length of 204 cm and the minimum transverse width of 24 cm reported by Riggs (1904:241). However, the B. altithorax humerus looks rather less gracile to the naked eye than that of B. brancai, and careful measurement from Riggs’s plate LXXIV yields a GI of 7.12, indicating that the true value of the minimum transverse width is closer to 28.5 cm. As noted by Riggs (1903:300-301), the surface of the distal end of this humerus has flaked away in the process of weathering. Careful comparison of the humeral proportions with those of other sauropods (Taylor and Wedel, in prep.) indicates that the missing portion of this bone would have extended approximately a further 12 cm, extending the total length to 216 cm and so increasing the GI to 7.53 – still less gracile than any B. brancai humerus except the outlier, but more gracile than any other sauropod species except Lusotitan atalaiensis (8.91), and much more gracile than the humerus of any non-brachiosaurid sauropod (e.g., Diplodocus Marsh, 1878 sp., 6.76; Malawisaurus dixeyi Jacobs, Winkler, Downs and Gomani, 1993, 6.20; Mamenchisaurus constructus Young, 1958, 5.54; Camarasaurus supremus Cope, 1877, 5.12; Opisthocoelicaudia skarzynskii Borsuk-Bialynicka, 1977, 5.00 – see Taylor and Wedel, in prep.)

Implicit in this (though not spelled out, I admit) is that the humeri of brachiosaurs are slender proportional to their femora. So let’s take a look at the humerus and femur of Giraffatitan, as illustrated in Janensch’s beautiful 1961 monograph of the limbs and girdles of Tendaguru sauropods:

Janensch1961-tendaguru-limbs--plates-AJ--giraffatitan-limb-bones

The first thing you’ll notice is that the humerus is way longer than the femur. That’s because Janensch’s Beilage A illustrates the right humerus of SII (now properly known as MB R.2181) while his Beilage J illustrates the right femur of the rather smaller referred individual St 291. He did this because the right femur of SII was never recovered and the left femur was broken, missing a section in the middle that had to be reconstructed in plaster.

(What’s a Beilage? It’s a German word that seems to literally mean something like “supplement”, but in Janensch’s paper it means a plate (full-page illustration) that occurs in the main body of the text, as opposed to the more traditional plates that come at the end, and which are numbered from XV to XXIII.)

How long would the intact SII femur have been? Janensch (1950b:99) wrote “Since the shaft of the right femur is missing for the most part, it was restored to a length of 196 cm, calculated from other finds” (translation by Gerhard Maier). Janensch confused the left and right femora here, but assuming his length estimate is good, we can upscale his illustration of St 291 so that it’s to SII scale, and matches the humerus. Here’s how that looks:

Janensch1961-tendaguru-limbs--plates-AJ--giraffatitan-limb-bones-scaled

Much more reasonable! The humerus is still a little longer, as we’d expect, but not disturbingly so.

Measuring from this image, the midshaft widths of the femur and humerus are 315 and 207 pixels respectively, corresponding to absolute transverse widths of 353 and 232 mm — so the femur is broader by a factor of 1.52. That’s why I expressed surprise on learning that Benson et al (2014) gave Giraffatitan a CF:CH ratio (circumference of femur to circumference of humerus) of only 1.12.

Anyone who would like to see every published view of the humeri and femora of these beasts is referred to Taylor (2009:fig. 5). In fact, here it is — go crazy.

Taylor (2009: figure 5). Right limb bones of Brachiosaurus altithorax and Brachiosaurus brancai, equally scaled. A-C, humerus of B. altithorax holotype FMNH P 25107; D-F, femur of same; G-K, humerus of B. brancai lectotype HMN SII; L-P, femur of B. brancai referred specimen HMN St 291, scaled to size of restored femur of HMN SII as estimated by Janensch (1950b:99). A, D, G, L, proximal; B, E, H, M, anterior; C, K, P, posterior; J, O, medial; F, I, N, distal. A, B, D, E modified from Riggs (1904:pl. LXXIV); C modified from Riggs (1904:fig. 1); F modified from Riggs (1903:fig. 7); G-K modified from Janensch (1961:Beilage A); L-P modified from Janensch (1961:Beilage J). Scale bar equals 50 cm.

Taylor (2009: figure 5). Right limb bones of Brachiosaurus altithorax and Brachiosaurus brancai, equally scaled. AC, humerus of B. altithorax holotype FMNH P 25107; DF, femur of same; GK, humerus of B. brancai paralectotype HMN SII; LP, femur of B. brancai referred specimen HMN St 291, scaled to size of restored femur of HMN SII as estimated by Janensch (1950b:99). A, D, G, L, proximal; B, E, H, M, anterior; C, K, P, posterior; J, O, medial; F, I, N, distal. A, B, D, E modified from Riggs (1904:pl. LXXIV); C modified from Riggs (1904:fig. 1); F modified from Riggs (1903:fig. 7); GK modified from Janensch (1961:Beilage A); LP modified from Janensch (1961:Beilage J). Scale bar equals 50 cm.

Notice that the femur of Giraffatitan, while transversely pretty broad, is freakishly narrow anteroposteriorly. The same is true of the femur of Brachiosaurus, although it’s never been shown in a published paper — I observed it in the mounted casts in Chicago.

Weird.

Calculations

So let’s take a wild stab at recalculating the mass of Giraffatitan using the Benson et al. formula. First, measuring the midshaft transverse:anteroposterior widths of the long bones gives eccentricity ratios of 2.39 for the femur and 1.54 for the humerus (I am not including the anterior prejection of the deltopectoral crest in the anteroposterior width of the humerus) . Dividing the absolute transverse widths above by these ratios gives us anteroposterior widths of 148 for the femur and 150 mm for the humerus. So they are almost exactly the same in this dimension.

If we simplify by treating these bones as elliptical in cross section, we can  approximate their midshaft circumference. It turns out that the formula for the circumference is incredibly complicated and involves summing an infinite series:

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But since we’re hand-waving so much anyway, we can use the approximation C = 2π sqrt((a²+b²)/2). where a and b are the major and minor radii (not diameters). For the femur, these measurements are 176 and 74 mm, so C = 848 mm; and for the humerus, 116 and 75 mm yields 614 mm. (This compares with FC=730 and HC=654 in the data-set of Benson et al., so we have found the femur to be bigger and the humerus smaller than they did.)

So the CF:CH ratio is 1.38 — rather a lot more than the 1.12 reported by Benson et al.  (Of course, if they measured the actual bones rather than messing about with illustrations, then their numbers are better than mine!)

And so to the mass formula, which Campione and Evans (2012) gave as their equation 2:

log BM = 2.754 log (CH+CF) − 1.097

Which I understand to use base-10 logs, circumferences measured in millimeters, and yield a mass in grams, though Campione and Evans are shockingly cavalier about this. CH+CF is 1462; log(1462) = 3.165. That gives us a log BM of 7.619, so BM = 41,616,453 g = 41,616 kg.

Comparison with Benson et al. (2014)

Midshaft measurements and estimates for SII long bones (all measurements in mm)
SV-POW! Benson et al.
Femur Humerus Femur Humerus
Transverse diameter 353 232 240
Transverse radius 176 116 120
Anteroposterior diameter 148 150 146
Anteroposterior radius 74 75 73
Circumference 848 614 730 654
Total circumference 1462 1384
Mass estimate (kg) 41,616 34,000

My new mass estimate of 41,616 kg is is a lot more than the 34,000 kg found by Benson et al. This seems to be mostly attributable to the much broader femur in my measurement: by contrast, the humerus measurements are very similar (varying by about 3% for both diameters). That leaves me wondering whether Benson et al. just looked at a different femur — or perhaps used St 291 without scaling it to SII size. Hopefully one of the authors will pass by and comment.

More to come on this mass estimate real soon!

References

 

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!

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(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):

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And a zoom into the relevant section:

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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:

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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.

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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.

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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.

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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!