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

If you’re thinking that it’s about time to look at some sauropod vertebrae from the Salt Wash member of the Morrison Formation, well, you’re gol-durned right, pardner. Let’s ride.

Here’s a vertebra sticking out of the rock. For once it’s not in cross-section. We’re simply looking at the posterior surface of a dorsal vertebra and bits of its associated ribs. Let’s stand it up correctly:

And, well, heck, Alex, I’d like to go ahead and solve the puzzle:

Figure on the right from Wedel and Taylor (2013a), and composed in turn from plates in Hatcher (1901, Diplodocus), Hatcher (1903, Haplocanthosaurus), and Gilmore (1936, Apatosaurus).

UPDATE: I had the discovery sequence wrong–this is one of the bones that was first found by photographer Guy Tal, who then put ReBecca Hunt-Foster onto the area. ReBecca has since gone on to become Monument Paleontologist at Dinosaur National Monument, but at the time she was working as a BLM paleontologist out of the Moab office. ReBecca then brought out some more of us out to take a look, and that was the genesis of my work with her and John in the Salt Wash.

John Foster and Cary Woodruff were both there when I saw this vertebra for the first time. I think we set a new record for a consensus among paleontologists in concluding that this vertebra belongs to Haplocanthosaurus. The super-tall, cathedral-esque laminae arching over the neural canal and the up-tilted transverse processes are absolutely diagnostic, and not present in any other Morrison sauropods. Haplocanthosaurus is one of the rarer sauropods in the Morrison, so it’s nice to have one in our Salt Wash fauna. Not least because of all the other awesome sauropods out there, it’s this weird little duck that my destiny seems to have become intertwingled with (exhibits A, B, C, D, E, and counting).

Speaking of: did you remember that the Western Science Center exhibit on the Snowmass Haplocanthosaurus is still up for a couple more months? Have you seen it? Go see it!

Life restoration of Haplocanthosaurus by Brian Engh, for the Western Science Center exhibit.

So, hey, rock and roll, we have Haplocanthosaurus, and that is legitimately exciting. Between that and Camarasaurus (covered here) we have the primitive-and-unspecialized end of the Morrison sauropods sewn up. Anything bigger or more exotic? Why, yes, in fact. Stay tuned.

This is another “Road to Jurassic Reimagined, Part 2″ post. You know the drill: Part 1 is here, Part 2 will be going up here in the near future, Part 3 will be along sometime after that.

References

In the last post, we looked at some sauropod vertebrae exposed in cross-section at our field sites in the Salt Wash member of the Morrison Formation. This time, we’re going to do it again! Let’s look at another of my faves from the field, with Thuat Tran’s hand for scale. And, er, a scale bar for scale:

And let’s pull the interesting bits out of the background:

Now, confession time. When I first saw this specimen, I interpeted it as-is, right-side up. The round thing in the middle with the honeycomb of internal spaces is obviously the condyle of a vertebra, and the bits sticking out above and below on the sides frame a cervical rib loop. I figured the rounded bit at the upper right was the ramus of bone heading for the prezyg, curved over as I’ve seen it in some taxa, including the YPM Barosaurus. And the two bits below the centrum would then be the cervical ribs. And with such big cervical rib loops and massive, low-hanging cervical ribs, it had to an apatosaurine, either Apatosaurus or Brontosaurus.

Then I got my own personal Cope-getting-Elasmosaurus-backwards moment, courtesy of my friend and fellow field adventurer, Brian Engh, who proposed this:

Gotta say, this makes a lot more sense. For one, the cervical ribs would be lateral to the prezygs, just as in, oh, pretty much all sauropods. And the oddly flat inward-tilted surfaces on what are now the more dorsal bones makes sense: they’re either prezyg facets, or the flat parts of the rami right behind the prezyg facets. The missing thing on what is now the right even makes sense: it’s the other cervical rib, still buried in a projecting bit of sandstone. That made no sense with the vert the other way ’round, because prezygs always stick out farther in front than do the cervical ribs. And we know that we’re looking at the vert from the front, otherwise the backwards-projecting cervical rib would be sticking through that lump of sandstone, coming out of the plane of the photo toward us.

Here’s what I now think is going on:

I’m still convinced that the bits of bone on what is now the left side of the image are framing a cervical rib loop. And as we discussed in the last post, the only Morrison sauropods with such widely-set cervical ribs are Camarasaurus and the apatosaurines. So what makes this an apatosaurine rather than a camarasaur? I find several persuasive clues:

  • If we have this thing the right way up, those prezygs are waaay up above the condyle, at a proportional distance I’ve only seen in diplodocids. See, for example, this famous cervical from CM 3018, the holotype of A. louisae (link).
  • The complexity of the pneumatic honeycombing inside the condyle is a much better fit for an apatosaurine than for Camarasaurus–I’ve never seen that level of complexity in a camarasaur vert.
  • The bump on what we’re now interpreting as the cervical rib looks suspiciously like one of the ventrolateral processes that Kent Sanders and I identified in apatosaurine cervicals back in our 2002 paper. I’ve never seen them, or seen them reported, in Camarasaurus–and I’ve been looking.
  • Crucially, the zygs are not set very far forward of the cervical ribs. By some rare chance, this is pretty darned close to a pure transverse cut, and the prezygs, condyle (at its posterior extent, anyway), and the one visible cervical rib are all in roughly the same plane. In Camarasaurus, the zygs strongly overhang the front end of the centrum in the cervicals (see this and this).

But wait–aren’t the cervical ribs awfully high for this to be an apatosaurine? We-ell, not necessarily. This isn’t a very big vert; max centrum width here is 175mm, only about a third the diameter of a mid-cervical from something like CM 3018. So possibly this is from the front of the neck, around the C3 or C4 position, where the cervical ribs are wide but not yet very deep. You can see something similar in this C2-C5 series on display at BYU:

Or, maybe it’s just one of the weird apatosaurine verts that has cervical rib loops that are wide, but not very deep. Check out this lumpen atrocity at Dinosaur Journey–and more importantly, the apatosaur cervical he’s freaking out over:

UPDATE just a few minutes later: Mike reminded me in the comments about the Tokyo apatosaurine, NSMT-PV 20375, which has wide-but-not-deep cervical ribs. In fact, C7 (the vertebra on the right in this figure) is a pretty good match for the Salt Wash specimen:

UpchurchEtAl2005-apatosaurus-plate2-C3-6-7

NSMT-PV 20375, cervical vertebrae 3, 6 and 7 in anterior and posterior views. Modified from Upchurch et al. (2005: plate 2).

UPDATE the 2nd: After looking at it for a few minutes, I decided that C7 of the Tokyo apatosaurine was such a good match for the Salt Wash specimen that I wanted to know what it would look like if it was similarly sectioned by erosion. In the Salt Wash specimen, the prezygs are sticking out a little farther than the condyle and cervical rib sections. The red line in this figure is my best attempt at mimicking that erosional surface on the Tokyo C7, and the black outlines on the right are my best guess as to what would be exposed by such a cut (or pair of cuts). I’ve never seen NSMT-PV 20375 in person, so this is just an estimate, but I don’t think it can be too inaccurate, and it is a pretty good match for the Salt Wash specimen.

Another way to put it: if this is an apatosaurine, everything fits. Even the wide-but-not-low-hanging cervical ribs are reasonable in light of some other apatosaurines. If we think this is Camarasaurus just because the cervical ribs aren’t low-hanging, then the pneumatic complexity, the height of the prezygs, and the ventrolateral process on the cervical rib are all anomalous. The balance of the evidence says that this is an apatosaurine, either a small, anterior vert from a big one, or possibly something farther back from a small one. And that’s pretty satisfying.

One more thing: can we take a moment to stand in awe of this freaking thumb-sized cobble that presumably got inside the vertebra through one its pneumatic foramina and rattled around until it got up inside the condyle? Where, I’ll note, the internal structure looks pretty intact despite being filled with just, like, gravel. As someone who spends an inordinate amount of time thinking about how pneumatic vertebrae get buried and fossilized, I am blown away by this. Gaze upon its majesty, people!

This is another “Road to Jurassic Reimagined, Part 2″ post. As before, Part 1 is here, Part 2 will be going up here in the near future. As always, stay tuned.

References

Nature’s CT machine

January 28, 2020

Because I’ve worked a lot on the anatomy and evolution of air-filled bones in sauropod dinosaurs, I’ve spent most of my career looking at images like this:

CT sections through a cervical vertebra of an apatosaurine (Apatosaurus or Brontosaurus), OMNH 1094. Wedel (2003b: fig. 6). Scale bar is 10cm.

…and thinking about images like this:

Physical sections through pneumatic vertebrae of Giraffatitan. Janensch (1950: figs. 71-73).

Turns out, that’s pretty good practice for fossil prospecting in the Salt Wash member of the Morrison Formation, where we frequently find things like this:

That’s a bit hard to read, so let’s pull it out from the background:

This is almost certainly a pneumatic vertebra of a sauropod, sectioned more-or-less randomly by the forces of erosion to expose a complicated honeycomb of internal struts and chambers. The chambers are full of sandstone now, but in life they were full of air. I say “almost certainly” because there is small chance that it could belong to a very large theropod, but it looks more sauropod-y to me (for reasons I may expand upon in the comments if anyone is curious).

I’m not 100% certain what section this is. At first I was tempted to read it as a transversely-sectioned dorsal, something like the Allosaurus dorsal shown in this post (link) but from a small, possibly juvenile sauropod. But the semi-radial, spoke-like arrangement of the internal struts going to the round section at the bottom looks very much like the inside of the condyle of a sauropod cervical or cervico-dorsal–compare to fig. 71 from Janensch (1950), shown above. And of course there is no reason to suspect that the plane of this cut is neatly in any of the cardinal anatomical directions. It is most likely an oblique cut that isn’t purely transverse or sagittal or anything else, but some combination of the above. It’s also not alone–there are bits and bobs of bone to the side and above in the same chunk of sandstone, which might be parts of this vertebra or of neighboring bones. Assuming it is a sauropod, my guess is Diplodocus or Brachiosaurus, because it looks even more complex than the sectioned cervicals and dorsals I’ve seen of Haplocanthosaurus, Camarasaurus, or the apatosaurines.

Sometimes we can do a little better. This is one of my favorite finds from the Salt Wash. This boulder, now in two parts, fell down out of a big overhanging sandstone cliff. When the boulder hit, it broke into two halves, and the downhill half rolled over 180 degrees, bringing both cut faces into view in this photo. And there in the boulder is what looks like two vertebrae, but is in fact the neatly separated halves of a single vertebra. I know I refer to erosion and breakage as “Nature’s CT machine”, but this time that’s really on the nose. Let’s take a closer look:

Here’s what I see:

It’s a proportionally long vertebra with a round ball at one end and a hemispherical socket at the other end: a cervical vertebra of a sauropod. Part of the cervical rib is preserved on the upper side, which I suspect is the left side. The parapophysis on the opposite side is angled a bit out of the rock, toward the camera. Parapophyses of sauropod cervicals tend to be angled downward, and if we’re looking at the bottom of this vertebra, then the rib on the upper side is the left. The right cervical rib was cut off when the boulder broke. All we have on this side are the wide parapophysis and the slender strut of the diapophysis aiming out of the rock toward the missing rib, which must still be embedded in the other half of the boulder–and in fact you can see a bit of it peeking out in the counterpart in the wide shot, above.

Can we get a taxonomic ID? I think so, based on the following clues:

  • The cervical ribs are set waaay out to either side of the centrum, by about one centrum diameter. Such wide-set cervical ribs occur in Camarasaurus and the apatosaurines, Apatosaurus and Brontosaurus, but not typically in Diplodocus, Brachiosaurus, or other Morrison sauropods.
  • The cervical rib we can see the most of is pretty slender, like those of Camarasaurus, in contrast to the massive, blocky cervical ribs of the apatosaurines (for example).
  • We can see at least bits of both the left and right cervical ribs in the two slabs–along with a section right through the centrum. So the cervical ribs were set wide from the centrum but not displaced deeply below it, as in Camarasaurus, and again in contrast to the apatosaurines, in which the cervical ribs are typically displaced far below (ventral to) the centrum (see this).
  • This one is a little more loosey-goosey, but the exposed internal structure looks “about right” for Camarasaurus. There is a mix of large and small chambers, but not many small ones, and nothing approaching the coarse, regular honeycomb we’d expect in Apatosaurus, Brontosaurus, or Diplodocus, let alone the fine irregular honeycomb we’d expect in Barosaurus or Brachiosaurus (although I will show you a vert like that in an upcoming post). On the other hand, the internal structure is too complex for Haplocanthosaurus (compare to the top image here).
  • As long as Camarasaurus is on the table, I’ll note that the overall proportions are good for a mid-cervical of Cam as well. That’s not worth much, since vertebral proportions vary along the column and almost every Morrison sauropod has cervicals with this general proportion somewhere in the neck, but it doesn’t hurt.

So the balance of the evidence points toward Camarasaurus. In one character or another, every other known Morrison sauropod is disqualified.

When it’s too dark to hunt for sauropods, you can look at other things.

Now, Camarasaurus is not only the most common sauropod in the Morrison, it’s also the most common dinosaur of any kind in the formation. So this isn’t a mind-blowing discovery. Still, it’s nice to be able to get down to a genus-level ID based on a single vertebra fortuitously sectioned by Mother Nature. In upcoming posts, I’ll show some of the more exciting critters that we’ve been able to ID out of the Salt Wash, ‘we’ here including Brian Engh, John Foster, ReBecca Hunt-Foster, Jessie Atterholt, and Thuat Tran. Brian will also be showing many of these same fossils in the next installment of Jurassic Reimagined. Catch Part 1 here (link), and stay tuned to Brian’s paleoart channel (here) for more in the very near future.

References

Heinrich Mallison sent me this amazing photo, which he found unattributed on Facebook:

Infuriatingly, I’ve not been able to track down an original source for this: searching for the text just finds a bunch of reposts on meme sites, and Google’s reverse image search just reports a bunch of hits on Reddit:

The line-drawing shows some scientific understanding of bird skeletons, so I imagine someone put real thought into this and is unhappy that the image is propagating uncredited. If that person reads this, please leave a comment: I’d love to credit it properly.

Anyway … what’s going on here?

Birds (like all vertebrates) have two tubes running down the ventral aspect of the neck (i.e. below the vertebrae): the trachea, for breathing, and the oesophagus, for swallowing. But these both open into the back of the mouth and are not piped up past it. I’ve not dissected enough bird heads to show this clearly, but when I was taking Veronica apart the trachea was pretty visibly ending in the mouth cavity, not plumbed up past the mouth into the nasal space:

So yes, I think it’s true: shoebills can bulge their spines out of their mouths.

Why? My best guess that there’s just nowhere else for the spine to go when the neck is retracted. There’s a big empty space in the mouth, why let it go to waste?

Over the past few years I’ve dropped hints here and there about the work I’ve been doing in the Morrison Formation of Utah with Brian Engh, John Foster, ReBecca Hunt-Foster, Jessie Atterholt, and Thuat Tran. I’ve been quiet about that (with one notable exception), but we’re finally ready to show you all what we’ve been up to. Brian has put together a short series of documentaries to take you into the Morrison and show you what we’ve found and why we’re excited about it. Your journey begins here:

We’ll have a lot more to say about this, building up to a big reveal this coming Thursday, so stay tuned!

Amazing diagram of the path of the vagus nerve and its branches in the neck, thorax, and abdomen, from Wilson-Pauwels et al. (1988). The gonads aren’t drawn here, but they do receive vagal innervation.

This isn’t new to science, it’s just one of the cool little quirks of human and comparative anatomy that more people should be aware of.

Quick-quick background: autonomic (unconscious, involuntary) innervation of the body comes in two flavors, sympathetic and parasympathetic. Sympathetic nerves mostly handle the fight-or-flight response, parasympathetics are feed-breed-and-read. You could also think of them as the “oh crap emergency” and “hum-drum housekeeping” branches of the nervous system. Sympathetic nerves to the whole body are derived from the spinal cord between T1 and L2, and parasympathetics come from certain cranial nerves and from the sacral part of the spinal cord. If a refresher on all of this would be handy, please see this.

The most awesome nerve in the body is cranial nerve X, the vagus nerve. “Vagus” means “wandering” in Latin; it’s the same root from which we get ‘vagabond’ and ‘vagrant’. As the name implies, the nerve gets around–various branches innervate just about all your viscera from the soft palate at the back of your mouth to the first half of your large intestine. And, as stated in the title of the post, your gonads.

That’s actually pretty weird, even for a nerve from your skull that innervates most of your digestive tract. The reason why it’s weird is that your embryonic hindgut (descending colon, sigmoid colon, and rectum) and most of your pelvic viscera and reproductive system get their parasympathetic innervation from the pelvic splanchnic nerves. The gonads are buried in all of that, and they may get some pelvic splanchnic innervation as well, but they also get innervated by the vagus nerves. (Note for fellow arch-pedants: yes, I know there’s evidence that the pelvic splanchnics should technically be considered sympathetic, but I’m not going down that rabbit hole right now.)

Like most of the weird stuff that goes on in our bodies, the reason why the gonads get vagal innervation is developmental. The gonads actually start developing pretty high up in the abdomen, not far below the diaphragm, and their nerve and blood supply are established at that point. High in the abdomen is firmly in vagus nerve territory, so the gonads get vagal innervation. Then later the gonads descend, in both sexes, and they drag their nerves and blood vessels along with them, which is why the gonadal vessels in both sexes come off the aorta near or with what end up being the renal arteries. (Kidneys do the opposite thing, developing down low and then climbing the aorta, swapping arteries as they go, but that’s a story for another day.) In males the testes take the final leap through the abdominal wall to descend into the scrotum, but ovaries descend almost as far, from up by the diaphragm down to the bowl of the pelvis, or at least to its rim. (Most of the time: just as males can have undescended testes, females can have incompletely-descended ovaries; they turn up now and then in the anatomy lab.)

Incidentally, fellas, this is why you feel sick to your stomach when you get kicked in the groin–the nerves to your testicles come out of the same plexus that serves your stomach and most of your intestines, and the pain fibers go back the same way.

For some super-interesting work on determining gonadal innervation using viral tracing, see Gerendai et al. (2005, 2009). I may quote some choice passages down in the comments.

Another great figure from Wilson-Pauwels et al. (1988), this time showing the path of vagal sensory fibers from the periphery to the brain (and again omitting the reproductive tract). Note the nucleus solitarius in the medulla oblongata, where vagal sensory fibers travel first on their way to the brain.

As is often the case in biology, things get stranger still. In females it’s not just the ovaries that are innervated by the vagus nerve, but part of the cervix and vagina as well. This was hypothesized by Komisaruk et al. (1997), based on the fact that some women with complete spinal cord injuries (‘complete’ here meaning ‘spinal cord cut all the way through’) could still experience genital sensation. It was confirmed by Komisaruk et al. (2004), who found that women with complete transection of the spinal cord could achieve orgasm from vaginal stimulation. Their fMRI study showed that the posterior part of the nucleus solitarius in the brainstem–which receives sensory fibers from the vagus nerve–was active in the process. I assume that there is some esoteric bit of embryology that explains how vagus fibers end up in the vagina, probably something to do with the mesonephric ducts. But I don’t know what that is off the top of my head, so I’ll have to go hit the books (again).

If you dig the diagrams I’ve used here, definitely go track down a copy of Wilson-Pauwels et al. (1988). There are newer versions of the same book that have full-color illustrations, but I think the single-color-nerve-on-black-and-white figures from the 1988 version are cleaner and more readable. It’s not just a good book on the cranial nerves, it’s a master class on clear visual presentation of complicated material. Unfortunately it is not cheap; even used paperback copies start around $40 unless you get lucky. UPDATE: However, through the generosity of Dr. Wilson-Pauwels, the illustrations and captions from the 2013 3rd edition are freely available for teaching purposes at this link. Go avail yourself of this phenomenal resource!

Anyway, the moral of the story is that, male or female, you have nerve fibers that exit your skull through the jugular foramen, pass down your neck behind your carotid arteries, follow your esophagus and stomach to the networks of nerves that run your guts, and run as impossibly slender fibers on the surfaces of the blood vessels that go to your testes or ovaries and vagina. You run your ‘nads from your brain, not just by way of the spinal cord but also by nerves that come straight out of your friggin’ head. Have fun with that thought.

References

  • Gerendai, I., Banczerowski, P. and Halász, B. 2005. Functional significance of the innervation of the gonads. Endocrine 28(3): 309-318.
  • Gerendai, I., Tóth, I.E., Boldogkői, Z. and Halász, B. 2009. Recent findings on the organization of central nervous system structures involved in the innervation of endocrine glands and other organs; observations obtained by the transneuronal viral double-labeling technique. Endocrine 36(2): 179-188.
  • Komisaruk, B.R., Gerdes, C.A. and Whipple, B., 1997. Complete’spinal cord injury does not block perceptual responses to genital self-stimulation in women. Archives of Neurology, 54(12): 1513-1520.
  • Komisaruk, B.R., Whipple, B., Crawford, A., Grimes, S., Liu, W.C., Kalnin, A. and Mosier, K. 2004. Brain activation during vaginocervical self-stimulation and orgasm in women with complete spinal cord injury: fMRI evidence of mediation by the vagus nerves. Brain Research 1024(1-2): 77-88.
  • Wilson-Pauwels, L., Akesson, E.J. and Stewart, P.A. 1988. Cranial Nerves: Anatomy and Clinical Comments. Toronto: BC Decker.