On Monday we visited the Prehistoric Museum in Price, Utah, the Cleveland-Lloyed dinosaur quarry, and sites in the Mussentuchit member of the Cedar Mountain Formation. Many thanks to Marc Jones for the photos.

1 - CEU Prehistoric Museum

In 2010, the College of Eastern Utah became Utah State University – Eastern, and the CEU Prehistoric Museum in Price is now officially the USU Eastern Prehistoric Museum. The dinosaurs in the center of exhibit hall are being remounted. These include Allosaurus, Stegosaurus, Camptosaurus (mounted, toward top of photo), and Camarasaurus (dismounted, on floor). Most of the mounts are either real material or casts of real material from the nearby Cleveland-Lloyd quarry.

The museum has many other exhibits besides the one shown above. The paleo wing alone covers two floors, and upstairs there are great displays on Cretaceous dinosaurs from the area, including Jurassic and Cretaceous ankylosaurs, a ceratopsian, and numerous tracks.

2 - Cleveland-Lloyd orientation

After leaving Price we went to the Cleveland-Lloyd dinosaur quarry, which has produced over 20,000 separate elements, including the remains of something like 50-60 allosaurs. The smallest ones are hatchlings–several elements from literally cat-sized baby allosaurs are known from the quarry.

3 - Mark Loewen teaching

Mark Loewen (right) talked to us about how the quarry might have formed, and what it’s like to work there. On the left in the above photo you can see a bunch of disarticulated Allosaurus bones suspended above the floor on wires. These are placed to give an idea of the three-dimensional jumbling of the bones in the matrix. It is almost impossible to jacket one bone or even several without hitting others. I remember how that goes from working at the OMNH sauropod bonebed in the Cloverly–it’s almost impossible to avoid blowing through some bones just to get others out of the ground.

4 - Camarasaurus pelvis with bite marks

Here’s one of a handful of bones from the quarry with bite marks. This is the pelvis of a Camarasaurus, lying upside down, anterior toward the wall. The back end of the right ilium is heavily tooth-marked.

After Cleveland-Lloyd we stopped at a couple of sites in the Mussentuchit. I’m not going to blog about those because they are active sites that are still producing fossils. Unfortunately it is not uncommon for fossil localities on public land to be looted and vandalized by unscrupulous private collectors. I don’t want to give those a-holes any help, so I’ve deliberately not shown any photos of about half a dozen of the most interesting sites that we visited during the conference. It sucks to know cool things and not be able to tell people about them, but if I blab then I put those cool things at risk. Happily there is a lot of active research going on, including one or two projects that got hatched at this conference, so hopefully I will be able to tell some of these stories soon.

5 - MMFC14 conveners Jim Rebecca and John

Instead, I will close this series (for now) with a shout-out to the people who convened and ran the field conference: Jim Kirkland (left) and ReBecca Hunt-Foster (middle). John Foster (right) also contributed a lot of time, energy, effort, and expertise.

Jim Kirkland is amazing. If you know him, you know that his heart is as big and outgoing as his booming voice. His knowledge of and enthusiasm for the mid-Mesozoic sites in western Colorado and eastern Utah have driven a lot of science over the past quarter century, and he shared that knowledge and enthusiasm compulsively on this trip. My head is so full of new stuff, it’s honestly hard to think. I wish I had a solid week to just digest everything I learned at the conference.

My highest praise and thanks go to ReBecca. Thanks to her hard work and organization, the whole field conference ran about as much like clockwork as something this complicated can–and when it didn’t run smoothly, like that flat tire on Saturday, she took charge and got us back on track. She was basically den mom to about 60 folks, from teenagers to retirees, from at least ten countries and four continents, and somehow she did it all with unflagging grace and good humor. The fact that she had her appendix out just two or three days before the start of the conference only cements my admiration for what she pulled off here.

I had a fantastic time. I hope they do another one.

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Illustration talk slide 39

Illustration talk slide 40

Illustration talk slide 41

Illustration talk slide 42

Illustration talk slide 43

The Sauroposeidon stuff is cribbed from this post. For the pros and cons of scale bars in figures, see the comment thread after this post. MYDD is, of course, a thing now.

Previous posts in this series.

Reference:

Wedel, M.J., and Taylor, M.P. 2013. Neural spine bifurcation in sauropod dinosaurs of the Morrison Formation: ontogenetic and phylogenetic implications. Palarch’s Journal of Vertebrate Palaeontology 10(1): 1-34. ISSN 1567-2158.

In a comment on the previous post, Steve P. asked whether “Apatosaurusminimus might not be a Apatosaurus specimen after all — particularly, an Apatosaurus ajax individual resembling NSMT-PV 20375, the one in the National Science Museum, Tokyo, that Upchurch et al. (2005) so lavishly monographed.

Initially, I dismissed this idea out of hand, because the “Apatosaurusminimus sacrum-pelvis complex is so very different to that of the “Brontosaurus” illustrated by Hatcher (1903: fig. 4), as seen in an earlier post. But on going back to the Upchurch et al. monograph I realised that their sacrum-ilium complex is very different from Hatcher’s. Here it is, cleaned up from scans and re-composed in the same format as the Camarasaurus and “Apatosaurusminimus from last time, for easy comparison.

Sacrum and fused ilia of Apatosaurus ajax NSMT-PV 20375. Top row: dorsal view with anterior to left. Middle row, left to right: anterior, right lateral (reversed), posterior. Bottom row: ventral view with anterior to left. Modified from Upchurch et al. (2005: plate 4 and text-figure 9).

Here’s Hatcher’s “Brontosaurus” illustration (from his plate 4) again:

I’m not sure what to make of this. The Tokyo Apatosaurus seems to be intermediate in some respects between Hatcher’s specimen and “Apatosaurusminimus.

One important difference is that the neural spines are much taller in Hatcher’s illustration than in the Tokyo Apatosaurus. Could that be ontogenetic? (IIRC the Tokyo individual is subadult). Or are they in fact different species? Or is it just individual variation?

I don’t know. Anyone?

References

  • Hatcher, J.B. 1903. Osteology of Haplocanthosaurus with description of a new species, and remarks on the probable habits of the Sauropoda and the age and origin of the Atlantosaurus beds; additional remarks on Diplodocus. Memoirs of the Carnegie Museum 2:1-75.
  • Upchurch, Paul, Yukimitsu Tomida, and Paul M. Barrett. 2005. A new specimen of Apatosaurus ajax (Sauropoda: Diplodocidae) from the Morrison Formation (Upper Jurassic) of Wyoming, USA. National Science Museum Monographs No.26. Tokyo.

 

Upchurch et al. (2005)

I mentioned a few posts ago that Matt and I are working on a redescription of AMNH 675, a sauropod specimen referred by Mook (1917) to “Apatosaurusminimus, but which everyone knows is not Apatosaurus. We plan to share the illustrations from this in-progress paper as we prepare them, so here is perhaps the key one:

Sacrum and fused ilia of AMNH 675, “Apatosaurus” minimus. Top row: left lateral and right lateral; middle row: dorsal, with anterior to top; bottom row, anterior and posterior. Scale bar = 1 m. Click through for very high resolution (6283 x 6479).

The other material comprising this specimen consists of a partial pubis and two ischia, one of which is complete. We’ll show you these once we’ve prepared the illustrations.

What actually is it? Well, we don’t know yet. it has a strange mix of advanced diplodocoid and advanced macronarian features. A preliminary phylogenetic analysis is inconclusive. We have some more approaches to follow up before we’re ready to nail a conclusion to the door.

Reference

Mook, Charles C. 1917. Criteria for the determination of species in the Sauropoda, with description of a new species of Apatosaurus. Bulletin of the American Museum of Natural History 38:355-360.

Caudal pneumaticity in saltasaurines. Cerda et al. (2012: fig. 1).

Earlier this month I was amazed to see the new paper by Cerda et al. (2012), “Extreme postcranial pneumaticity in sauropod dinosaurs from South America.” The title is dramatic, but the paper delivers the promised extremeness in spades. Almost every figure in the paper is a gobsmacker, starting with Figure 1, which shows pneumatic foramina and cavities in the middle and even distal caudals of Rocasaurus, Neuquensaurus, and Saltasaurus. This is most welcome. Since the 1990s there have been reports of saltasaurs with “spongy bone” in their tail vertebrae, but it hasn’t been clear until now whether that “spongy bone” meant pneumatic air cells or just normal marrow-filled trabecular bone. The answer is air cells, loads of ’em, way farther down the tail than I expected.

Caudal pneumaticity in diplodocines. Top, transverse cross-section through an anterior caudal of Tornieria, from Janensch (1947: fig. 9). Bottom, caudals of Diplodocus, from Osborn (1899: fig. 13).

Here’s why this is awesome. Lateral fossae occur in the proximal caudals of lots of neosauropods, maybe most, but only a few taxa go in for really invasive caudal pneumaticity with big internal chambers. In fact, the only other sauropod clade with such extensive pneumaticity so far down the tail are the diplodocines, including Diplodocus, Barosaurus, and Tornieria. But they do things differently, with BIG, “pleurocoel”-type foramina on the lateral surfaces of the centra, leading to BIG–but simple–camerae inside, and vertebral cross-sections that look like I-beams. In contrast, the saltasaurines have numerous small foramina on the centrum and neural arch that lead to complexes of small pneumatic camellae, giving their vertebrae honeycomb cross-sections. So caudal pneumaticity in diplodocines and saltsaurines is convergent in its presence and extent but clade-specific in its development. Pneumaticity doesn’t get much cooler than that.

Pneumatic ilia in saltasaurines. Cerda et al. (2012: fig. 3).

But it does get a little cooler. Because the stuff in the rest of the paper is even more mind-blowing. Cerda et al. (2012) go on to describe and illustrate–compellingly, with photos–pneumatic cavities in the ilia, scapulae, and coracoids of saltasaurines. And, crucially, these cavities are connected to the outside by pneumatic foramina. This is important. Chambers have been reported in the ilia of several sauropods, mostly somphospondyls but also in the diplodocoid Amazonsaurus. But it hasn’t been clear until now whether those chambers connected to the outside. No patent foramen, no pneumaticity. It seemed unlikely that these sauropods had big marrow-filled vacuities in their ilia–as far as I know, all of the non-pneumatic ilia out there in Tetrapoda are filled with trabecular bone, and big open marrow spaces only occur in the long bones of the limbs. And, as I noted in my 2009 paper, the phylogenetic distribution of iliac chambers is consistent with pneumaticity, in that the chambers are only found in those sauropods that already have sacral pneumaticity (showing that pneumatic diverticula were already loose in their rear ends). But it’s nice to have confirmation.

So, the pneumatic ilia in Rocasaurus, Neuquensaurus, and Saltasaurus are cool because they suggest that all the other big chambers in sauropod ilia were pneumatic as well. And for those of you keeping score at home, that’s another parallel acquisition in Diplodocoidea and Somphospondyli (given the apparent absence of iliac chambers in Camarasaurus and the brachiosaurids, although maybe we should bust open a few brachiosaur ilia just to be sure*).

* I kid, I kid.**

** Seriously, though, if you “drop” one and find some chambers, call me!

Pectoral pneumaticity in saltasaurines. Cerda et al. (2012: fig. 2).

But that’s not all. The possibility of pneumatic ilia has been floating around for a while now, and most of us who were aware of the iliac chambers in sauropods probably assumed that eventually someone would find the specimens that would show that they were pneumatic. At least, that was my assumption, and as far as I know no-one ever floated an alternative hypothesis to explain the chambers. But I certainly did not expect pneumaticity in the shoulder girdle. And yet there they are: chambers with associated foramina in the scap and coracoid of Saltasaurus and in the coracoid of Neuquensaurus. Wacky. And extremely important, because this is the first evidence that sauropods had clavicular air sacs like those of theropods and pterosaurs. So either all three clades evolved a shedload of air sacs independently, or the basic layout of the avian respiratory system was already present in the ancestral ornithodiran. I know where I’d put my money.

There’s loads more interesting stuff to talk about, like the fact that the ultra-pneumatic saltasaurines are among the smallest sauropods, or the way that fossae and camerae are evolutionary antecedent to camellae in the vertebrae of sauropods, so maybe we should start looking for fossae and camerae in the girdle bones of other sauropods, or further macroevolutionary parallels in the evolution of pneumaticity in pterosaurs, sauropods, and theropods. Each one of those things could be a blog post or maybe a whole dissertation. But my mind is already thoroughly blown. I’m going to go lie down for a while. Congratulations to Cerda et al. on what is probably the most important paper ever written on sauropod pneumaticity.

References

  • Cerda, I.A., Salgado, L., and Powell, J.E. 2012. Extreme postcranial pneumaticity in sauropod dinosaurs from South America. Palaeontologische Zeitschrift. DOI 10.1007/s12542-012-0140-6
  • Janensch, W. 1947. Pneumatizitat bei Wirbeln von Sauropoden und anderen Saurischien. Palaeontographica, Supplement 7, 3:1–25.
  • Osborn, H. F. 1899. A skeleton of Diplodocus. Memoirs of the American Museum of Natural History 1:191–214.

Sometimes you just can’t make this stuff up.

You may recall a story from the Onion Our Dumb Century book, allegedly from 1904, about the skeleton of Satan being discovered in Wyoming. Mike used his occult powers to put together this scan from freely available online sources:

If you scrutinize the above image carefully, you’ll see that ‘Satan’ is an Allosaurus (I’m no theropod booster, but I always thought that was a little harsh on T. rex).

Why am I telling you this? Because last week Mike and I were toiling in the big bone room in the basement of the AMNH when we came across AMNH 666.

It’s an ilium. (Of course it would have to be an appendicular element. Vertebrae are from on high [or dorsal, if you prefer].)

Of Allosaurus!

The stomach-churning color here could be a manifestation of diabolical power, or just what happens when you try to photograph a pink specimen label on a yellow-orange forklift.

After this harrowing encounter, we cleansed our bodies, minds, and souls with street-vendor hot dogs and The Avengers.* That particular mode of exorcism may not be the most effective–I felt distinctly dodgy that evening. But the next day we received illumination at the Altar of Sauropod Awesomeness and were soon back to what we jokingly refer to as normal.

* The best way to see The Avengers is by going up to the observation deck of the Empire State Building shortly beforehand, so big swathes of the Manhattan skyline will still be in your mental RAM during the big final battle. I understand it’s not an option for everyone.

The Magi present gifts to the Christ child