At last it can be told: we found a big Brachiosaurus in the Salt Wash
January 30, 2020
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:
- Brachiosaurus, Potter Creek, Colorado: 213cm
- Giraffatitan, MB.R.2181/SII specimen, Tanzania: 213cm
- Brachiosaurus, holotype, Colorado: ~213cm (preserved length is 203cm, but the distal end is eroded, and it was probably 213cm when complete)
- Giraffatitan, XV3 specimen, Tanzania: 210cm
- *** NEW Brachiosaurus, FHPR 17108, Utah: 201cm
- Ruyangosaurus (titanosaur from China): ~190cm (estimated from 135cm partial)
- Turiasaurus (primitive sauropod from Spain): 179cm
- Notocolossus (titanosaur from Argentina): 176cm
- Paralititan (titanosaur from Egypt): 169cm
- Patagotitan (titanosaur from Argentina): 167.5cm
- Dreadnoughtus (titanosaur from Argentina): 160cm
- 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.
- “Brachiosaurus bone 2 metres long excavated in Utah with help of horses” – Australian Broadcasting Corporation
- “Fossil hunters use horses to pull 150 million-year-old six-foot Brachiosaurus arm bone from Utah gully in race against time before it was washed away” – Daily Mail
- “Paleontologists recover Brachiosaurus remains in southern Utah” – Southern Utah Independent
- “Bone of rare long-necked dinosaur found in Southern Utah desert” – St. George News
- “Top 5 weekend stories on St. George News” – St. George News
- Brian Engh and Matt Wedel talk about the find on the I Know Dino podcast
- “This 6-Foot Brachiosaurus Fossil Hitched a Ride With Two Clydesdale Horses” – Atlas Obscura
- “A pair of horses helped excavate a hulking Brachiosaurus fossil in Utah” — Smithsonian Magazine
References
- Jensen, James A. 1987. New brachiosaur material from the Late Jurassic of Utah and Colorado. Great Basin Naturalist 47(4):592–608.
- Riggs, Elmer S. 1903. Brachiosaurus altithorax, the largest known dinosaur. American Journal of Science 15(4):299-306.
- Riggs, E.S. 1904. Structure and relationships of opisthocoelian dinosaurs. Part II, the Brachiosauridae. Field Columbian Museum, Geological Series 2, 6, 229-247.
- Taylor, Michael P. 2009. A re-evaluation of Brachiosaurus altithorax Riggs 1903 (Dinosauria, Sauropoda) and its generic separation from Giraffatitan brancai (Janensch 1914). Journal of Vertebrate Paleontology 29(3):787-806.
Sauropod Vertebra Picture of the Week 
January 30, 2020 at 9:37 am
Excellent.
I bet when you go back you are hoping to find some nice pneumatic Brachiosaurus vertebrae or even a skull.
January 30, 2020 at 10:31 am
This is really wonderful!
When I was a kid I wished to became a paleontologist, and even now after 20 years for me is amazing to see your work on the field!
Really an amazing work
January 30, 2020 at 10:34 am
That. Is. So. Cool. One of these years, before I get too much older, I may have to join you on one of these trips. May is tough for our schedule, though. Mid June, tho…
January 30, 2020 at 12:45 pm
By the way, the Potter Creek humerus is now mounted vertically at the Smithsonian.
January 30, 2020 at 2:57 pm
Fantastic! Having known Brachiosaurus since I was a kid, and later having realized that the East African brachiosaur was given its own genus Giraffatitan and Brachiosaurus had a European cousin named Lusotitan, the new Brachiosaurus specimen from the Salt Wash makes clear than maybe more exciting Brachiosaurus specimens are waiting to be found or rediscovered in museum collections.
January 30, 2020 at 2:58 pm
I hope Brian will have footage of him actually finding the bone. Would be amazing to see what he sees as the discovery was being made.
January 30, 2020 at 3:45 pm
Brilliant..made such exciting reading. Thank you for sharing I certainly will be watching this space.
January 30, 2020 at 5:16 pm
We captured the moment of Matt seeing it for the first time. I was too shook when I first laid eyes on it I didn’t even think to take a picture. That said, you get to see exactly how it looked in situ when I filmed Matt’s initial reaction. The discovery will be in Jurassic Reimagined part 2, and the extraction in part 3.
Stay tuned yall :}
http://www.youtube.com/DinosaursReanimated
January 30, 2020 at 7:02 pm
I probably shouldn’t say, but having been involved with KU and the Korean student situation, I believe those limb bone materials were actual one of several Camarasaurs we took out out of Jurassic formation north from Lance Creek WY .northwest of Newcastle in the early 90s one was mounted at Dike Hall at Ku for about 9 years. Now no longer on display.
The material that left the US is in a dino museum in Korea. I know more but….. well you know the deal.
January 30, 2020 at 8:19 pm
I saw one of the camarasaurs mounted at KU when I was there in early 2001. As for the one in Korea, I’ve seen photos, and although the material is intriguing, I wouldn’t want to hazard a guess about the ID until I’ve seen more (it’s also frankly not my material to talk about). If I have all my facts straight, this is the same quarry, or at least the same field area, that produced a big manus that IIRC is in private hands, and a huge pes that was described by Maltese et al. in 2018.
If I ever get my head wrapped around all of the material from that quarry, the IDs, and where it all is now, I should do a blog post about it, if for no other reason than to fix my own understanding.
January 31, 2020 at 6:47 am
Well, that was quite a humerus anecdote!
January 31, 2020 at 1:25 pm
on the one hand, sure, it’s big in absolute terms, but in relative terms it’s the shortest Brachiosaur humerus found, if I understand your list correctly; it’s the 3rd Brachiosaur found, and according to your post this humerus and its match are the 3rd and 4th found.
Maybe you should name it “Runty”
or Samwise.
January 31, 2020 at 4:17 pm
You make a good point! And the smallest Brachiosaurus humerus to date is still over 2m–that’s not bad at all.
February 1, 2020 at 2:38 pm
Yes, yes, yes! to “Runty”!
February 1, 2020 at 9:16 pm
So where are the baby Brachiosaurus; did they live in an environment where they weren’t preserved or were they so delicious that the scavengers cleaned up all the carcasses?
February 1, 2020 at 9:52 pm
That is THE question about the Morrison and basically every other sauropod-bearing formation. Everything we think we know about sauropod life history says that every reproductive-age female was dropping dozens to hundreds of eggs every year. And although there are a lot more juvenile sauropods from the Morrison than you might expect from reading the literature (because most of them are incomplete things in collections that have never been described), our sample does seem tilted toward the big ones. My pet hypothesis is that baby sauropods mostly had one of two fates: to grow up (a scant handful), or to be rendered into theropod poop (the vast majority)–leaving very few to potentially become fossils.
I think both of your hypotheses are viable. If juveniles preferred dense cover in forests, they might have had few opportunities to get buried in depositional environments (or for their bones to survive; forest soils are sometimes too acidic for bones to be preserved). And there were undoubtedly a lot of critters who would look at a dead baby sauropod as a quick shot of calories–basically everything from Compsognathus-sized micro-theropods up to monsters like Saurophaganax.
February 2, 2020 at 12:50 am
Yes, interesting that there are not exactly a lot of baby Saurophaganax or other theropods known either.
Maybe they were in the forests hunting baby sauropods or sticking close to their parents so they got to grow up.
February 2, 2020 at 12:59 am
Actually I just had another thought regarding the undescribed scraps of small sauropods in museums; can you take what is known about the growth trajectories of sauropods and their bones and work backwards to get an idea of what the remains of a hatchling or juvenile Brachiosaurus would look like and produce a wanted poster so that if people going through museum collections came across something similar it might jog their memories.
February 2, 2020 at 5:06 am
Lotta questions about missing baby sauropods and theropods. This leads me to ask the broader question: how common are baby anythings in the fossil record? Maybe this isn’t a weird aspect of sauropod or even dinosaur life history, and it’s more a phenomenon of fossilization. Heck, crocodylians live in their depositional environments and even then I can only think of a handful of instances where there are any preserved hatchlings / juveniles.
February 2, 2020 at 5:19 am
Huh. I feel like a right moron for never thinking about baby crocs in the fossil record. I mean, I know there are a _few_, but you’re absolutely right about crocs having a fairly r-selected life history and living right in the depositional environments. Same goes for baby turtles, I reckon. Maybe most babies of most species just get eaten? So maybe the relative scarcity of baby sauropods is only weird if, like me, one hasn’t considered the relative scarcity of baby everythings.
February 2, 2020 at 12:54 pm
I was thinking about baby crocs myself. I lived in Tanzania for several years, walked along crocodile rivers, saw quite a few croc bones (and hippo bones), but never a dead baby croc, let alone a little skeleton. And yet juvenile mortality is massive. I think they get eaten completely and quickly, or they decompose rapidly.
So, preservational bias against small bodies and bones at work here?
But then, even at mass burial sites of Edmontosaurus and Shantungosaurus juveniles are extremely uncommon (not talking about nesting sites here of course), that I find harder to explain.
February 2, 2020 at 3:53 pm
Juvenile amphibians are pretty common in the fossil record – a number of Permian species are known from plentiful larvae or juveniles and few or no adults – but these remains are mostly preserved by catastrophic events – pond dessication, hypoxia, etc., that would discourage scavenging.
IIRC, there are some hadrosaur bonebeds that are mainly juveniles, or at least subadults, such as the North Slope “Ungrunaaluk” beds. So the lack of juveniles in other hadrosaur assemblages may just indicate that the animals lived in age-segregated groups.
A thought – if juvenile sauropods in certain formations are preferentially removed from potential fossilization by getting completely consumed, shouldn’t all terrestrial vertebrates in the same size class as juvenile sauropods be equally rare for the same reason? I know there are a few small-bodied ornithischians and theropods known from the Morrison, but I have no idea how common they are. Maybe an enterprising grad student could graph frequency versus (some proxy for body size) of Morrison vertebrate fossils and see if there’s a steep cliff on the left side of the distribution curve that indicates the “small enough to be completely devoured” size class.
A second thought – could ichnological records be used to check actual versus preserved size distributions?
February 2, 2020 at 9:49 pm
There is an episode of the croclog podcast which mentions that when saltwater crocs find turtle nesting sites, they remember when the baby turtles hatch, and come back year after year to hoover up lots of hatchling turtles.
Easy to imagine something similar happening to hatchling sauropods.
February 2, 2020 at 9:57 pm
@nathanparker11:
I think that here you have nailed the key question.
I have no idea what the answer is.
February 2, 2020 at 10:09 pm
If sauropods were ecologically like nesting turtles they would congregate their nesting sites near an environment the juveniles could escape to, produce so many eggs that the predators were swamped and literally couldn’t eat any more and the surviving hatchlings would then leave the area to get to the safe environment as quickly as possible.
If adult sauropods were relatively invulnerable to predation their numbers would build up over time; just as marine turtles did historically before people started harvesting them and their eggs on an industrial scale.
February 3, 2020 at 10:10 am
nathanparker11 Says:
February 2, 2020 at 3:53 pm
“Maybe an enterprising grad student could graph frequency versus (some proxy for body size) of Morrison vertebrate fossils and see if there’s a steep cliff on the left side of the distribution curve that indicates the “small enough to be completely devoured” size class.”
Well, with regard to late Cretaceous hadrosaurs, there is such a thing (which you may be aware of already):
– There is a nice graph of Shantungosaurus frequency of femora:
https://archosaurmusings.wordpress.com/2014/11/24/a-population-of-shantungosaurus-the-largest-ornithischian/
– And there is a database of (Lance formation) Edmontosaurus mass bonebed in eastern Wyoming by SWAU univ., with a large number of femurs, tibia’s and fibula’s, from which one can make a graph:
https://fossil.swau.edu/
In both graphs you will see that there is no very sharp drop-off to the left side, but rather ‘natural’ looking distribution curve with a peak around adult (?) size and a gradual decline toward larger and smaller sizes.
The former seems logical, the latter surprising (?): subadults are relatively scarce, increasingly so toward smaller sizes. This something I would rather expect for a K-select species (like elephants), being very long-lived, producing few but well-cared-for offspring. Juveniles are absent in the Shantungosaurus graph, very scarce in the Edmontosarus database.
So, different environments for juveniles and then regular but small recruitment into the (sub)adult population? Or preservational bias? Or both?
February 3, 2020 at 1:28 pm
there are some mammals known from the Morrison – dryolestoids, multiturberculates, etc. However, it might be expected that tough mammal teeth could pass through a large predator’s digestive system and remain identifiable. That may not be true for sauropod teeth. What are sauropod teeth made of? All I know about them is they have very high replacement rates, which doesn’t seem promising.
If sauropod teeth or other bone fragments might survive digestion in identifiable form, that might be a way too look for juvenile sauropods – figure what bits of juvenile sauropod might survive being crunched up and digested by a large allosaur, and remain identifiable, at least to the level of being a sauropod, and look for those bits. However, it seems like sauropods might be among the most difficult groups to take this approach with, alongside things like pterosaurs and birds.
Makes me wish I knew something, anything, about the microvertebrate record of the Morrison.
February 4, 2020 at 5:06 pm
Another comparison I keep thinking of (which runs somewhat the opposite way of my previous comment) is with deer antler. In most species of deer, healthy males drop a set of antler every year. But in most environments, most antler don’t make it into the fossil record. They get chewed up and eaten. Porcupines, deer, moths, lots of animals eat them for calcium. Maybe lots of sauropod bone gets lost in a similar fashion; it might be crunchable by lots of animals (not just predators). Perhaps stegosaurs were calcium-hungry fiends (needed for all those big bony plates and spikes), and chewed up most of the bones the theropods missed. Maybe there were bone-munching specialized invertebrates which fed on sauropod bones (parallel to the antler specialist moths in the modern). But all the antler munching animals don’t completely prevent antler preservation; there were some places and times in the Pleistocene in which plenty of deer antler *were* preserved – example: Megaloceros antler found in Ireland.
February 5, 2020 at 4:10 pm
Congratulations! This is so awesome!
February 5, 2020 at 6:29 pm
Good thoughts, llewelly. (BTW I tidied your comment-hydra into a single bolt.) Sauropod teeth are made of enamel and dentin, like all other dino teeth; you can see some examples of worn and unworn Camarasaurus teeth in this post.
There are Morrison microsites, but not many, and some were deliberately passed over last century because they weren’t producing big impressive dinosaur skeletons–this is precisely what happened with Stovall’s Quarry 8 at Black Mesa in Oklahoma. Now, of course, Morrison microsites look like gold mines, which is why the OMNH has relocated that quarry, cleared it, and found the old quarry face. Further bulletins as events warrant!
February 6, 2020 at 11:45 am
Thank you, Matt, for tidying the comment hydra. My apologies for the nuisance.
February 6, 2020 at 11:54 pm
Ha, no worries. I’d rather have a good discussion even it takes some comment-thread-hacking to make that happen.
February 9, 2020 at 5:42 am
[…] 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 […]
February 9, 2020 at 7:47 pm
Could preservation be the bigger issue for juveniles than fossilization? That 2 meter humerus can’t have been exposed to the elements all that long before becoming damaged by the elements, and the bones of the baby Camerasaurus and Brontosaurus at my local CMNH are tiny by comparison – under similar conditions, they’d likely have been destroyed or so fragmented as to be unrecognizable.
And then, of course, there’s the problem of the delightful habit of Marsh and Cope of dynamiting their fossil beds when they left them, so who knows how badly that’s skewed findings.
February 9, 2020 at 11:14 pm
Dynamiting a quarry just to prevent someone else from using it is pretty vile, but I don’t think it has had much of an effect on our perception of Morrison diversity, because most of the really productive and influential quarries were discovered after the time of Marsh and Cope (Carnegie Quarry at Dinosaur National Monument, Cleveland Lloyd, Howe Quarry, Dry Mesa, etc.).
I think depositional context matters a lot for preservation. In the Salt Wash we find a lot of isolated bones in sandstone, but almost all of them are fist-sized up to log-sized. We don’t find tiny bones or isolated teeth, at all. But we’re also mostly looking in massive sandstones with lots of pebbles, and that’s probably enough flow to either grind up the little stuff or transport it farther downstream.
One reason I’m excited about the Brach site is those plant fossils in sandy clay indicate a more sedate depositional environment. It would be killer if we found some microverts in among the plant material.
Keep in mind that I am a comparative anatomist by training and application. I’ve had just about enough geology to get myself into trouble, but not enough yet to get myself back out. Also, thinking about how ancient ecosystems related to depositional environments related to taphonomic sorting is not easy or straighforward, at least for me, so I’m mostly relying on the findings of more experienced folks, and I may be unintentionally misrepresenting much of that!
February 16, 2020 at 10:27 pm
[…] not his new Brachiosaurus humerus — his photograph of the Chicago Brachiosaurus mount, which he cut out and cleaned up seven years […]
April 22, 2020 at 11:54 pm
I’m a retired professional film/still photographer and plastic model builder. I built a few dinosaurs a few years ago; (T-Rex, etc). I would like to sell them to some sort of museum.
If you are interested, please email me at the email listing and I can send you a few top quality digital images.
i live in nearby Irvine, California.
Cheers!
Rodney
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September 24, 2020 at 11:27 pm
Since this lists humeri of sauropods, anyone interested in a potential 1.88 meter titanosaur humerus from Kem Kem? It’s little known but it seems to be pretty big.
March 8, 2021 at 11:34 am
[…] I already had an Estwing hammer–one of blue-grip models–which is good, because the engraved one is going in my office, not to the field. (If you’re wondering why my field hammer looks so suspiciously unworn, it’s because my original was stolen a few years ago, and I’m still breaking this one in. By doing stuff like this.) […]
August 12, 2021 at 8:36 am
Its smaller than 188 cm probably, but i don’t know. Its huge though. My estimated size for UCRC PV 9 is 2.1 m for Humerus, rivalling Brachiosaur humeri
October 7, 2021 at 11:22 pm
[…] the complete right humerus of Brachiosaurus that we got out of the ground in 2019; that story is here. The humerus is in the prep lab at the Utah Field House of Natural History State Park Museum in […]
January 23, 2023 at 10:26 pm
[…] from Brachiosaur Gulch in Utah (the story of the discovery and excavation of that specimen is here). I used the image shown above, scaled to print at 7 feet by 3 feet. You can see that print lying […]
May 25, 2023 at 6:47 pm
[…] from England to visit those states for the first time in his life. We did some fieldwork out at Brachiosaur Gulch and visited quite a few museums and quarries around the Dinosaur Diamond, in a sort of […]