July 19, 2012
In a comment on the previous post, Steve P. asked whether “Apatosaurus” minimus 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 “Apatosaurus” minimus 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 “Apatosaurus” minimus 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 “Apatosaurus” minimus.
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?
- 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 “Apatosaurus” minimus, 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:
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.
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.
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.
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.
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!
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.
- 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.
June 24, 2012
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].)
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.
December 23, 2011
August 15, 2011
It’s been a little quiet around here lately. Mike has been slammed with day-job work, Darren is terminally busy as always, and I’m in my fall teaching block so I’ve been too busy to think. But life rolls on and there are announcements that need making. To wit:
Throughout the blogosphere, people produce fantastic writing for free. That’s great, but I believe that good writers should get paid for good work. To set an example, I choose ten pieces every month that were written for free and I donate £3 to the author. There are no formal criteria other than I found them unusually interesting, enjoyable and/or important.
It was an honor to be chosen; Ed’s a damn fine writer and has a knack for finding good stuff and pointing people to it. So why am I just blogging about this now, in August? I didn’t cover it at the time because the Science Writer Tip Jar runs on reader donations and I thought it would be a little gross to solicit money for myself. And I didn’t cover it right after because Ed’s been busy, too, and it sorta slipped off the radar for both of us. But at the end of last month he sent me a nice donation by PayPal, and I’m finally making good with the blogging about it.
What will I do with the dough? Inevitably, it will be spent on an epic meal of sushi for Mike and I. We don’t get to see each other very often, so when we do we have a sushipocalypse, and it’s pretty common for us to have ideas worth pursuing and publishing at these events. So ultimately the money will be plowed back into science, albeit indirectly. Thanks, Ed, and keep up the stellar work at NERS.
- Speaking of money, if you’d like to win a pile of it–4500 Euros, in fact–for the paleo paper you published in 2010, and get a nice trip to Spain in the bargain, I suggest you submit to Paleonturology 11, sponsored by Fundacion Dinopolis in Teruel, Spain. I know about this awesomeness because one of my papers won back in 2006, and I got a free trip to Spain in December, 2007 (story here). Winners have included papers by grad students and emeritus professors, on everything from trilobite eyes and bivalve shells to Pliocene hominids and dinosaur gastralia. The entrance form is super-simple and the whole process takes about as much time as it does to read this post. So if you published a paleo paper in the calendar year 2010 and you don’t enter, you’re just being silly. The deadline isn’t until November 15, but there’s no reason not to just sit down and do it right now. The form is somewhere on the Dinopolis website, but if your Spanish is as nonexistent as mine, you may find this PDF handy: Paleonturology 11 entrance form
- This Friday, August 19, I’ll be on Jurassic CSI, talking about big sauropods. Details, showtimes, and some photos are here. The photo up top, of me with an Apatosaurus pelvis at BYU, is borrowed from there.
That’s all for now; further bulletins as events warrant.
March 1, 2011
Let’s look a bit more closely at the holotype element of Brontomerus mcintoshi, which as we all remember is the juvenile left ilium OMNH 66430. Much of what we’ve said about Brontomerus is based on the shape of that ilium, so it’s important to get right. Several commentators have expressed skepticism about how we reconstructed, so I thought it would be worth taking the time to explain why we put it together we way we did.
First, let’s orient ourselves. Here is the torso from the skeletal inventory that was Figure 1 of the paper (Taylor et al. 2011, natch). In this version, I’ve highlighted the ilium in red. We’re looking at the left side of the animal, so the main part of the bone is further forward than the hip socket, towards the animal’s head.
As you’ll see from the area that we left shaded grey, a chunk is missing from the middle of the ilium, where it was damaged in the field. As the figure of the ilium in the paper shows clearly, what we actually saw in the OMNH collection was three chunks of bone: a big one consisting of the acetacular margin, pubic and ischiadic peduncles and most of the preacetabular blade; and two smaller fragments, each contributing part of the dorsal or posterior margin.
We spent a while in the OMNH collection playing with the three chunks to see how they best fit together. In doing this with the actual bones, we were able to take account of their curvature in the third dimension, which our figure don’t show — although a dorsal-view photo gives some idea.
Anyway, we this is what we came up with:
(Sorry if that image is getting a bit overfamiliar, but it’s worth seeing again in the context of this post.)
You’ll remember from the Clearing the Air post that Jim Kirkland, who excavated the ilium, felt that we’d got the two smaller fragments in the wrong places relative to the main chunk, and also that a fourth fragment which we’d missed also belongs to the ilium. He kindly sent a photo of how he’d reconstructed the ilium, and I used the arrangement of pieces in the photo as the basis for a “what if” alternative reconstruction.
So far, this is old news. But what was maybe not quite clear in the post is how very similar the two reconstructions really are. Let’s fix that: here they are side by side, with ours on the left and Jim’s on the right:
It seems pretty clear that even if Jim’s arrangement is correct (which Rich Cifelli disputes), that doesn’t affect the reconstruction in any significant way.
But the real question is why we put in that dotted line — and why we put it where we did. How do we know there wasn’t a normal-sized postacetabular lobe sticking out behind? This is what Jamie Headden wanted to know in an email to me shortly after the paper come out. With his kind permission, I reproduce the illustration that he prepared, showing (A) the reconstruction from the paper, and (B) how it might have been different:
The reason we rejected a reconstruction like the one in Jaime’s part B is explained (too) briefly in the paper (pp. 80-81):
The postacetabular lobe is reduced almost to the point of absence [...] The ischiadic peduncle is reduced to a very low ventral projection from almost the most posterior point of the ilium. The near absence of the ischiadic peduncle cannot be attributed to damage as the iliac articular surface is preserved. Immediately posterodorsal to this surface is a subtle notch between the peduncle and the very reduced postacetabular lobe. This notch and the areas either side of it are composed of finished bone, demonstrating that the great reduction of the postacetabular lobe, too, is a genuine osteological feature and not due to damage.
To my lasting annoyance, I didn’t take any posterior-view photos of the ilium back in 2007, so I can’t show you this finished bone as well as I’d like — this was back before I’d learned all my lessons on how to photograph bones. But here is a close-up of the posterovental extremity of the ilium, again from Fig. 2, showing the notch: I have left the postacetacular lobe in colour, and desaturated the ischiadic peduncle — the notch is between them.
This next photograph of the ilium, again in lateral view, is lit rather differently from the one we used in the figure, so that you can see a distinct shadow lying along the valley between the ischiadic peduncle and what there is of the postacetabular blade.
Here’s one that shows the main chunk of the ilium in anteromedial view: from here, you can more easily see the the distinction between the ischial peduncle (which projects towards the camera) and the preserved, ventralmost, part of postacetacular blade, which is further back.
And one in posteroventral view: this is similar to our Fig. 2b, but from a slightly more posterior (and medial) perspective, so that you can more easily see the mediolaterally compressed posterior lobe sticking out behind the broader ischial peduncle at top right:
What all these photos unfortunately do not show is the finished nature of the bone on the posterior margin of the postacetacular blade — on that, you just have to take our word.
But the point is this: we have the whole of the ischiadic peduncle and the ventralmost part of the postacetacular blade — we know that the posteriormost preserved part of the main chunk of ilium is not part of the peduncle (so that the postacetabular blade is missing), but that this really is the blade itself. And because the bone is not broken, we know that the trajectory of the posterior margin of the postacetabular blade was directed dorsally from the posterior point of the peduncle.
I hope that’s clear. What I really should have done, of course, was take my own good advice and get photos from every angle — and, ideally, pairs that would have allowed me to show the relevant features as anaglyphs.
Anyway, all this shows that the shape of the ilium really was pretty much as we reconstructed it — and, most, importantly, that the bizarre proportions we reported in Table 4 are correct: preacetabular blade, measured parallel to the longest axis of the ilium equal to 55% of total length; postacetabular blade equal to 0%.
Exactly how strange is this almost non-existent postacetabular blade? In the paper we described it as “remarkable”, but it’s not completely unprecedented. Lehman and Coulson (2002:fig. 8) showed the left ilia of six somphospondylians:
As you can see, the Euhelopus zdanskyi and Saltasaurus loricatus ilia both lack postacetabular blades (although Powell 1992:fig. 18 suggests that the posterior portion of the Saltasaurus ilium may be broken). Where Brontomerus is unique is in the combination of this postacetabular reduction with the enormous preacetabular blade.
All clear? Good.
“But wait!”, I hear you cry. “That ilium is juvenile! How do you know that its strange shape is not a juvenile feature?”
Stay tuned! All will be revealed.
- Lehman, Thomas M. and Alan B. Coulson. 2002. A juvenile specimen of the sauropod dinosaur Alamosaurus sanjuanensis from the Upper Cretaceous of Big Bend National Park, Texas. Journal of Paleontology 76(1):156-172.
- Powell, Jaime E. 1992. Osteología de Saltasaurus loricatus (Sauropoda-Titanosauridae) del Cretácico Superior del Noroeste Argentino. pp. 165-230 in: J. L. Sanz and A. D. Buscalioni (eds), Los Dinosaurios y su Entorno Biotico. Actas del Segundo Curso de Paleontologia en Cuenca. Instituto Juan de Valdés, Ayuntamiento de Cuenca. 397 pages.
- Taylor, Michael P., Mathew J. Wedel and Richard L. Cifelli. 2011. A new sauropod dinosaur from the Lower Cretaceous Cedar Mountain Formation, Utah, USA. Acta Palaeontologica Polonica 56(1):75-98. doi: 10.4202/app.2010.0073
February 26, 2011
Sorry for the very short post. We have some longer stuff planned, but we’ve been too busy to kick it out this week, and I wanted to leave you with something cool to ponder over the weekend. Here’s the ilium of Giraffatitan overlaid on that of Brontomerus, scaled to the same acetabulum diameter (Giraffatitan is HMN J1, left ilium, modified from Janensch 1961: pl. E, fig. 2; Brontomerus is of course OMNH 66430 from Taylor et al. 2011:fig. 2).
And here’s the same thing comparing Rapetosaurus and Brontomerus (Rapetosaurus is holotype FMNH PR 2209, left ilium, modified from Curry Rogers 2009: fig. 39B). This one was tricky to scale because the ilial margin of the acetabulum is so different in the two taxa.
Here is the same trick performed with the ilium of the canonical pretty basal neosauropod Camarasaurus — specifically, Camarasaurus supremus AMNH 5761 Il. 1, left ilium, modified from Osborn and Mook (1921: fig. 87). In this case, the proportions are so very different that it’s hard to make a meaningful superimposition: we tried to scale to equal acetabulum size, but probably that of the Camarasaurus was proportionally larger than in the other taxa illustrated in this post. Still, here it is:
Finally, in response to Paul Barrett’s comment on a subsequent article, here is a superimposition of the ilium of Alamosaurus on that of Brontomerus:
(Sorry about the poor quality of this one, but the only figure I could find of a complete Alamosaurus ilium was the line-drawing in Lehman and Coulson (2002:fig. 8) — none of the standard descriptive works seem to illustrate a complete or near-complete ilium.)
We had a figure like these in an early draft of the paper, but we ditched it because we felt that doing a broader comparative figure would be more valuable. But I like the kick in the brainpan that these overlays provide.
- Curry Rogers, Kristina. 2009. The postcranial osteology of Rapetosaurus krausei (Sauropoda: Titanosauria) from the Late Cretaceous of Madagascar. Journal of Vertebrate Paleontology 29:1046-1086.
- Janensch, Werner. 1961. Die Gliedmaszen und Gliedmaszengurtel der Sauropoden der Tendaguru-Schichten. Palaeontographica, suppl. 7 (1), teil 3, lief. 4: 177-235.
- Lehman, Thomas M. and Alan B. Coulson. 2002. A juvenile specimen of the sauropod dinosaur Alamosaurus sanjuanensis from the Upper Cretaceous of Big Bend National Park, Texas. Journal of Paleontology 76(1):156-172.
- Osborn, Henry Fairfield, and Charles C. Mook. 1921. Camarasaurus, Amphicoelias and other sauropods of Cope. Memoirs of the American Museum of Natural History, n.s. 3:247-387, and plates LX-LXXXV.
- Taylor, Michael P., Mathew J. Wedel and Richard L. Cifelli. 2011. A new sauropod dinosaur from the Lower Cretaceous Cedar Mountain Formation, Utah, USA. Acta Palaeontologica Polonica 56(1):75-98. doi: 10.4202/app.2010.0073
February 25, 2011
Many people in the paleontological community have probably seen the comments about our work on Brontomerus by Jim Kirkland. Most of these comments have been posted on Facebook or sent around by email. We have held off until now in responding to them because we wanted to have everything–both the criticisms and our responses–publicly available to everyone, not in the walled garden of Facebook. Jim has now stated on Facebook that we have permission to post his messages and respond to them, and his longest critique has been posted as a comment on the initial Brontomerus post.
All three of us–Mike, Matt, and Rich, the authors of the new paper describing Brontomerus–have known Jim for some time. He and Rich collaborated in the Cedar Mountain Formation for most of the 1990s, and basically split the catch, with Jim getting most of the dinosaurs and Rich getting the mammals. Matt has known Jim since the late 1990s, and has had many productive conversations with him about sauropods and faunal change in the Early Cretaceous of North America. Mike’s interactions with Jim have been more limited, mainly because they live on different continents, but he has spoken to Jim at meetings and they have exchanged occasional correspondence–always friendly–for years.
Not only has Jim been a friend of ours for some time, he also assisted with the Brontomerus project. Jim first alerted Rich to the existence of the quarry in 1994. Following Rich’s visit to the quarry in September of that year, Jim went out with Scott Madsen and Randy Nydam to collect the fossils of what would become Brontomerus in 1995, and the fossils were prepared under his guidance at Dinamation before being transported to the Oklahoma Museum of Natural History for curation. Jim was also helpful in providing information about the quarry and allowing us to cite personal communications from him in the paper.
We’ve all had long and productive working relationships with Jim for years, and we’d like to see those relationships continue. However, some of his comments are not only factually incorrect but also call our veracity and scientific judgment into question. We feel that the record should publicly be set straight.
In the rest of the post, we have the full text of Jim’s long SV-POW! comment and some of his comments from Facebook, followed by a breakdown of his specific claims and our responses to them.
Jim’s self-described rant
On February 23, Jim sent around an email with the subject “Brontomerus pdf and rant”. ReBecca recently posted a slightly longer version here on Jim’s behalf.
While, it is possible, that Brontomerus is a new species based solely on the juvenile ilium, there is no way based on the minimal contextual information known of this site, that one can say that all the sauropod material we collected at Hotel Mesa pertains to the same species.
When, I was first taken to this site in 1994, it had been opened by guys hoping to develop a commercial Morrison dinosaur quarry. The Bureau of Land Management (BLM) clearly did not OK this! Another party, who told me he had only advised them to get a permit, subsequently took me out to the site.
Examining this site, it was obviously in the Cedar Mt. Fm. [LINK] and of great interest to me, but politics being what they were, I could not get a BLM permit in Utah and as I had recognized a fair number of teeth and claws (theropods and crocs) in the site, I thought perhaps it might be a potential microvertebrate site, so I asked Rich Cifelli at the OMNH if he might be interested in the site. Rich put me on his Utah BLM permit and sent out Randy Nydam and I corralled Scott Madsen (then at Dinosaur National Monument (DNM) and we went out to evaluate the site for microvertebrates and salvage the exposed bones. This took us about 1.5 days (camped for two nights). Unfortunately, the matrix would not break down and thus the site could not be screenwashed for microvertebrates, so Rich lost interest in the site. We prepared all the bones in our (Dinamation Intl. Soc.) lab in Fruita, Colorado before sending them on to the OMNH with his crew when they returned to Oklahoma from working their Utah sites at the end of the following summer.
After, I became Utah’s State Paleontologist in 1999, I expressed interest in reopening the Hotel Mesa Quarry, as this was the only Albian age site in all of eastern Utah, but BLM policy was that all specimens from a given site needed to be reposited at the same repository. Therefore, since Utah paid my salary, it was impossible to justify excavating and preparing a collection of vertebrate materials and sending them to Oklahoma.
A few years ago, Mike Taylor informed me that he and Matt Wedel felt that there was a new sauropod taxon in the collections from Hotel Mesa. I was excited to learn this, as I figured they would seek to open the site and collect more specimens and data concerning this important locality.
I was deeply saddened to learn they had described the new sauropod taxa with no regard to establishing a base of contextual data to support its hypodym.
First there is no evidence to suggest that all the sauropod bones in the site pertain to the same taxon. The Holotype ilium (cute as a bugs ear, I must say, particularly before the shim went through the middle of it, when we flipped the scapula jacket), comes from a much smaller animal that the rest of the reported “hypodym”.
The nearly equivalent and geographically much closer Price River 2 Quarry preserves more than one sauropod taxon among the many hundreds of sauropod bones collected there. Staff at CEUs Prehistoric Museum pointed out that they had long cervicals similar to Sauropossiden and short stouter cervicals. Their new director Ken Carpenter sent me this picture [LINK] showing two morphs of ilia (at top of figure), one with a short prepubic portion and a stout pubic peduncle and on with a long prepubis and slender pubic peduncle. Thus, the Upper Albian part of Cedar Mt preserves a wealth of sauropods and this taxon promises to add to the general confusion regarding North America’s Early Cretaceous sauropods.
Also in terms of stratigraphy (and these guys are not completely at fault here, but if asked I would have told them), the Ruby Ranch Member is Albian in age from all our dating. Abydosaurus mcintoshi from DNM is not from the younger Mussentichit Mbr. but the upper Albian (Chure et al.’s 2010, date of ~104 Ma says that) and as stated in … our abstract coming out at GSA this spring and to be submitted as a manuscript long before that, An unconformity (sequence boundary) separates the basal Cenomanian (98-96 Ma) Mussentuchit from the Albian strata below it. Two date, there are no over lapping parts between Brontomerus mcintoshi and Abydosaurus mcintoshi and these two sites may nearly be equivalent.
The much older upper Barremian to basal Aptian Dalton Wells Quarry low in the Cedar Mt has at least 3 sauropod taxa among the numerous individuals in Brigham Young University’s collection. Remember the Cedar Mountain represents about as much time as the entire Upper Cretaceous.
Basically, the statement that the juvenile holotype belongs to the same taxon as the handful of adult material in the site is a stretch without some supporting taphonomic documentation (more excavation, as the site keeps going. However, the statement is a falsifiable hypothesis so is a scientific statement that needs testing.
Now that we are beginning to excavate our own sauropods, which thank god are at the base of the Cedar Mt. Fm., I’m actually beginning to care about the general taxonomic mess that Albian sauropods are in with the number of taxa described without overlapping parts.
Another observation that I accidentally made was that the reconstruction of the ilium in the paper, differs from that we made in preparing the specimen fresh from the field. These two reconstructions are shown in at the bottom of the picture. We figure this reconstruction from 1995 in Kirkland and Madsen, 2007, Fig. 13E, p. 15). On line at: [LINK]
I’m certainly curious what happened between Rich’s OMNH crew’s picking the specimens up and Mike and Matt’s beginning their research on it. Regardless of whatever happened, it is clear the proportions on the Holotype ilium need to be reappraised.
PLEASE, someone open up this quarry and generate some real information (it is an 8hr drive from Salt Lake City, so I do not have the funds to undertake this). The site is in the Dolores Triangle so the Hotel Mesa Site can only be approached from Colorado, so the Museum of Western Colorado is by far the closest institution to it.
AND; finally, the site is actually in the Burro Canyon Formation not the Cedar Mountain Formation as the name changes as you cross the Colorado River going east. So the stratigraphic level would be, for the sake of accuracy by best referred to as high in the Ruby Ranch Member of the Burro Canyon Formation. This is how it is show on the recently published 1X100,000 geological map of the area. Geological jargon that is useless to argue with unless you are going to publish the justification of changing the convention.
Oh and there are many dozens of sauropods waiting to be excavated in the Ceadar Mountain Formation during the “Age of Ankylosaurs.”
Done spouting off for the minute.
Jim’s Facebook comments
Besides the email/SV-POW! comment, Jim has posted some serious criticisms of the paper on Facebook. These started back in January, when the accepted manuscript of the as-yet-unpublished paper was inadvertently posted on the Acta site. Jim kindly took them down following our request that he do so. However, the deleted criticisms had already been seen by hundreds of people (Jim has 898 Facebook friends) and received many comments, so we feel that it is appropriate to publicly respond to them.
[January 28] Since Abydosaurus mcintoshi and Brontomerus mcintoshi are essentially from the same stratigraphic horizon ~ 150 kilometers apart and have no overlapping parts yet. It is an interesting synonymy since the species name would not change. We have all these sauropod skeletons in the Cedar Mountain, lets not describe scrap.
[January 28] I have wanted to see the Hotel Mesa site (turned over to OMNH) excavated for more than a decade. To describe a dinosaur from scrap salvaged from site and to leave rest rotting in the ground is irresponsible!
[January 28] Jim Kirkland: WTF I oversaw the collection of it all, as salvage over a couple of daysl None of these guys have been to site (more there). No way, you can say anything, but the type illium goes to this species.
Darren Naish: Are you sure that none of the guys have been to the site? Err…Rich Cifelli?
Jim Kirkland: I guarantee it, they would never find it.
[February 23] I just realized that they reconstructed the ilium of Brontomeris wrong! See my Hotel Mesa album. It is not thunder thighs, but at most quivering thighs! I would say it throws a big hook into the entire thing.
[February 23] There is no evidence that anything was stolen from the site or smashed for that matter. They simply uncovered it and inquired about a commercial permit.[speaking here of the alleged vandalism of the site by commercial collectors]
Specific claims, and our responses
We’re rather baffled by some of Jim’s statements. Rather than go through the email and Facebook comments line by line or in chronological order, we’ve distilled his criticisms into a number of specific claims, which appear here with our responses.
Claim 1: None of the authors ever visited the quarry.
Source: Facebook, “None of these guys have been to site…I guarantee it, they would never find it.”
Response: This not just incorrect, but insulting. From the paper (Taylor et al. 2011: 76):
One of us (RLC), who had already been working in Lower Cretaceous rocks of the region, was notified about the site through the courtesy of James I. Kirkland, and was guided to it by Bill Hawes of Grand Junction, Colorado, in September 1994. Additional collecting at the site for OMNH was conducted by Randall L. Nydam and James I. Kirkland in March 1995.
In an email to Matt and Mike with permission to cite, Rich wrote:
I took the information directly from my field notes and I remember the place pretty well. Of course I was there!
Claim 2: We erred in describing the site as being part of the Cedar Mountain Formation rather than the Burro Canyon Formation.
Source: SV-POW! comment, “the site is actually in the Burro Canyon Formation not the Cedar Mountain Formation as the name changes as you cross the Colorado River going east. So basically the proper description of the site would say, it is in the upper part of the Ruby Ranch Mbr. of the Burro Canyon Formation.”
Response: We acknowledge this in the paper, and clearly state that our discussion of the site as part of the CMF is one of convenience (Taylor et al. 2011: 76):
Stratigraphically, OMNH V857 lies in a sequence of Lower Cretaceous rocks interposed between the Morrison Formation (Kimmeridgian) below and the Dakota Formation (Cenomanian) above. Westward, these rocks are recognized as the Cedar Mountain Formation; eastward, the Burro Canyon Formation. The arbitrary dividing line between these entities is generally placed at the Colorado River (Stokes 1952; Tschudy et al. 1984) which technically places OMNH V857 within the Burro Canyon Formation. However, we will refer to the locality as belonging to the more widely recognized Cedar Mountain Formation, as it is in this formation that comparable specimens are known, and the stratigraphy and sedimentology do not change across the arbitrary border.
It is also worth noting that in his long comment, Jim himself discusses the quarry as part of the Cedar Mountain Formation, presumably out of convenience: “Examining this site, it was obviously in the Cedar Mt. Fm.” (from the third paragraph of his SV-POW! comment).
Claim 3: The quarry probably has more than one sauropod taxon, because other CMF quarries sometimes have more than one sauropod taxon. (conflicts with Claim 8)
Source: SV-POW! comment, “First there is no evidence to suggest that all the sauropod bones in the site pertain to the same taxon. The Holotype ilium (cute as a bugs ear, I must say, particularly before the shim went through the middle of it, when we flipped the scapula jacket), comes from a much smaller animal that the rest of the reported “hypodym”.
“The nearly equivalent and geographically much closer Price River 2 Quarry preserves more than one sauropod taxon among the many hundreds of sauropod bones collected there.”
Response: This is a possibility we discuss extensively in the paper (Taylor et al 2011: 79), but so far there is no evidence to support it. All of the material is consistent with a single taxon, most likely a basal somphospondyl, but conservatively a camarasauromorph. (We plan to talk much more in a subsequent article about this tentative assignment of all the material to a single taxon.)
There is a more general point to be made here. Any time someone erects a new taxon, the idea that the taxon is actually distinct from other, previously named, taxa is a hypothesis subject to further testing. Anytime someone refers material to a taxon, that is likewise a hypothesis. If we pretended to be any more certain about the referral than we actually are, we’d be lying. But we’d be equally in error if we didn’t point out that the null hypothesis is that all of the material belongs to one taxon. If contrary evidence comes to light, we’ll take it into account and move on–that’s how science works.
If someone find a complete titanosaur skeleton with an ilium like the holotype of Brontomerus, and someone else turns up a complete rebbachisaur with a scapula like the one currently referred to Brontomerus, great! Name the rebbachisaur (a North American rebbachisaur would rock!), remove the scapula from the Brontomerus Referred Material list, and move on. As we made clear in the paper, Brontomerus is based on, and diagnosed by, the holotype ilium alone.
Claim 4: There is no evidence that anything was stolen or destroyed from the site.
Source: Facebook, “There is no evidence that anything was stolen from the site or smashed for that matter. They simply uncovered it and inquired about a commercial permit.” Also repeated second-hand as a comment on Dinosaur Tracking, here.
Response: In an email with permission to cite, Rich wrote:
Yes, of course it had been excavated: we have proof in my notes and in Randy Nydam’s field notes. The comments about bone strewn around and being used to hold pieces of blue tarp are, unfortunately, accurate.
What’s more puzzling is that all three of us have received emails from Jim going back to 2007 that clearly state that the quarry was vandalized. For example (and note the explicit permission to cite):
Date: Mon, 17 Mar 2008 10:22:12 -0600
From: James Kirkland
To: Mike Taylor
Subject: Re: Another Hotel Mesa pers. comm.
[...]. The small ilium was under the scapula (completely hidden and the shim went through the middle of it, but we were able to prepare it with it’s entire margin reconstructed. (collected by Jim Kirkland, Scott Madsen, & Randy Nydam from site that had been uncovered previously by vandals). [...]
Claim 5: The quarry is full of more and better sauropod material.
Source: Facebook, “To describe a dinosaur from scrap salvaged from site and to leave rest rotting in the ground is irresponsible!”
Response: Any material exposed near the surface at Hotel Mesa in 1994 and 1995 is long gone by now, crumbled by 16 years of freeze/thaw cycles and erosion by wind and water. There may be more material deeper down, a possibility that we have always acknowledged, but since no one has ever seen that material, it is impossible to say if it’s better than what we have, or if it even exists at all. This is actually not unusual for dinosaurs; many taxa are known from quarries that are not worked to exhaustion and later produce more material. One of our express aims in writing this paper was to to provide the impetus for further excavation in the quarry, and there was no prospect of that happening before we started working on it.
Claim 6: It was irresponsible of us to name a new dinosaur based on such incomplete material.
Source: Facebook, “We have all these sauropod skeletons in the Cedar Mountain, lets not describe scrap.”
Response: Although incomplete, the material still bears numerous autapomorphies that clearly indicate that it is a new taxon based on currently available data (see point 3, above, on hypotheses).
Since the material in the quarry was not articulated, we would have had to choose an isolated element as the holotype even if we had more material (and the ilium would still have been the obvious choice because it is so unusual). This is absolutely critical: in a bonebed of disarticulated elements, it wouldn’t matter if we had just the ilium or 5000 bones, we’d still have to pick one element as the holotype and refer everything else to it. Anyone describing a new taxon from disarticulated elements in a bonebed faces the same decision: for example, Kirkland et al. (2005), in their description of the basal therizinosaur Falcarius, nominated a partial braincase as the holotype and referred all the other material.
Claim 7: We erred in attributing Abydosaurus to the Mussentuchit member of the Cedar Mountain Formation.
Source: SV-POW! comment, “Abydosaurus mcintoshi from DNM is not from the younger Mussentichit Mbr. but the upper Albian (Chure et al.’s 2010, date of ~104 Ma says that) and as stated in … our abstract coming out at GSA this spring and to be submitted as a manuscript long before that,”
Facebook, “Abydosaurus mcintoshi and Brontomerus mcintoshi are essentially from the same stratigraphic horizon” [Brontomerus is from the Ruby Ranch member]
Response: The only published peer-reviewed work on the Abydosaurus quarry (Chure et al. 2010) places it in the Mussentuchit member. Jim’s abstract was not available to us when we were writing the paper, and if we had the option to choose between the conclusions of a peer-reviewed paper and those of an unpublished abstract, we’d still have followed the paper. Abydosaurus could actually be from the Ruby Ranch member, but we will wait for the published evidence, and to see what Chure et al. have to say in response.
Claim 8: Because Abydosaurus is from the Ruby Ranch member, Brontomerus might simply be Abydosaurus. (conflicts with Claim 3)
Source: Facebook, “Abydosaurus mcintoshi and Brontomerus mcintoshi are essentially from the same stratigraphic horizon ~ 150 kilometers apart and have no overlapping parts yet. It is an interesting synonymy”
Response: The hypothesis that Abydosaurus is from the Ruby Ranch member is far from convincingly demonstrated (see above). The Ruby Ranch member has at least two sauropods other than Brontomerus, and the Yellow Cat member has between three and five, so the idea that there is only one sauropod genus in each member of the CMF, and that therefore Brontomerus must be synonymous with Abydosaurus, is insupportable. Potential synonymies among Early Cretaceous North American sauropods are acknowledged and discussed extensively in the paper (Taylor et al. 2011: 87-88, 91-92).
Also, we note that back in January, Jim was concerned that Brontomerus was synonymous with Abydosaurus (not enough new sauropods in the quarry), and now in his comment he is concerned that there might be more than one taxon in the quarry (too many new sauropods). Which is it, and what aspects of our discussion of these problems in the paper does he find incomplete?
Claim 9: Jim’s photo of the reconstructed ilium shows that our reconstruction is wrong and that our conclusions are therefore suspect.
Source: Facebook, “I just realized that they reconstructed the ilium of Brontomeris [sic] wrong! See my Hotel Mesa album. It is not thunder thighs, but at most quivering thighs! I would say it throws a big hook into the entire thing.”
Response: Yesterday (February 23) we received an email from Jim, with this photo:
The body of the email:
I just realized that the ilium is reconstructed wrong in the paper. Here is how we reconstructed it straight in from the field..
Jim’s reconstruction is different from ours, but that does not automatically make it correct. This just in by email (with permission to cite) from Brontomerus co-author Rich Cifelli, who is curator at the Oklahoma Museum of Natural History where the fossils are curated:
From: Rich Cifelli
To: Mathew Wedel, Mike Taylor
Date: 25 February 2011 00:45
Subject: restorations of Kirkland vs. Taylor et al.
I have re-examined the various pieces of the holotype ilium (OMNH 66430). Our restoration stands as the only one that is really plausible, and is the best match considering the thickness, curvature, preservation, and surface texture of the three main pieces (large section including acetabulum, peduncles, and pre-acetabular blade; followed by thin strip of margin; followed posteroinferiorly by “Oklahoma-shaped” piece with margin). The other piece shown by Kirkland (roughly rhomboidal in outline) was omitted by us because it does not include any of the bone margins (contra Jim’s restoration) or contacts with other pieces: it fit somewhere in the large space posterior to the pre-acetabular blade and dorsal to the acetabulum.
Kirkland’s restoration cannot be “straight from the field” because it is obviously incorrect in placement, orientation, and side shown for the rhomboidal piece. As said, this fragment does not contain any of the bone margin: all of the edges, including that which he depicts as lying along the posterior-posterodorsal margin of the ilium, are jagged and broken. Color, surface texture, and an important morphological feature also show that he depicts this piece upside down. That feature is a ridge which separated attachment places for two sacral ribs, shown by Kirkland to be lateral (facing outward) but which of course should be medial.
But, all right, suppose Jim had been right about how the pieces should fit together: here’s a new recon by Mike that follows the photo Jim sent. Note that all the pieces fit comfortably within the very same dotted reconstruction line as in Fig. 2 of the paper.
It is also important to realize that the ilium is oriented differently in the two photos. The photo on the left in the comparison image, from Taylor et al. (2011: fig. 2), is a straight lateral view, looking straight down the laterally-oriented axis of the acetabulum. The preacetabular blade of the ilium angles out anterolaterally, as shown in our Figure 2B. In Jim’s photo, on the right of the comparison image, the preacetabular blade is lying flat on a table, which puts the acetabulum at an angle to the camera; the photo is effectively in posterolateral view rather than orthogonal, and this is the source of all the significant differences between the two photos. Take Jim’s reconstruction, mentally rotate it laterally through 20-30 degrees to look straight down the acetabulum, and his post-acetabular expansion would fit comfortably into the dotted line we drew, as Mike’s new recon shows.
The diagnostic features (autapomorphies) of the ilium are (Taylor et al. 2011: 78):
- Preacetabular lobe 55% of total ilium length, longer than in any other sauropod;
- Preacetabular lobe directed anterolaterally at 30 degrees relative to the sagittal plane, but straight in dorsal view and vertically oriented;
- Postacetabular lobe reduced to near absence;
- Ischiadic peduncle reduced to very low bulge;
- Ilium proportionally taller than in any other sauropod—height is 52% of total length, compared with a maximum of 45% in other sauropods.
If Jim’s reconstruction were right, it would only change the margin of the iliac crest, so it couldn’t affect characters 1, 2, or 4. His reconstruction still shows the postacetabular lobe reduced to near-absence (3), which still leaves the ilium proportionally taller than in any other sauropod (5). In short, the version he favors doesn’t affect the proportions or autapomorphies one whit.
The alternative reconstruction is valuable because it points out the existence of a missing piece of the wing of the ilium. However, not only is it wrong in the position of that piece, even if it was right it wouldn’t affect our morphological, taxonomic, or functional interpretations of Brontomerus at all.
Thanks for slogging through this long, probably not-terribly-interesting post. We’ll soon return to normal service, with more information on Brontomerus — and that awesome life restoration.
- Chure, D., Britt, B.B., Whitlock, J.A., and Wilson, J.A. 2010. First complete sauropod dinosaur skull from the Cretaceous of the Americas and the evolution of sauropod dentition. Naturwissenschaften (online preprint). doi:10.1007/s00114-010-0650-6
- Kirkland, J. I., Zanno, L. E., Sampson, S. D., Clark, J. M. and DeBlieux, D. D. 2005. A primitive therizinosauroid dinosaur from the Early Cretaceous of Utah. Nature 435: 84-87.
- Taylor, M. P., Wedel, M.J., and Cifelli, R.L. 2011. A new sauropod dinosaur from the Lower Cretaceous Cedar Mountain Formation, Utah, USA. Acta Palaeontologica Polonica 56(1):75-98. doi: 10.4202/app.2010.0073
February 23, 2011
Today is the culmination of a project that I and Matt, and our co-author Rich Cifelli, are very proud of: the publication of the new sauropod, Brontomerus mcintoshi. Go and read the the paper — it’s open access, thanks to the good folks at Acta Palaeontologica Polonica.
This project started for Matt many years ago — he first mentioned it to me on 15 May 2004, and we first discussed it in detail in July that year. It’s amazing to realise that very nearly seven years have slipped by since then. But it’s done at last, and Brontomerus mcintoshi is born today!
So, what is Brontomerus, and why should you care? It’s a kick-ass new sauropod — literally — which extends the range of known sauropod morphology and contributes to the growing record of Early Cretaceous sauropod diversity in North America, plus its name means “thunder-thighs” and sounds kind of like Brontosaurus. What’s not to like?
We know Brontomerus from elements representing about 10% of a skeleton — not much, admittedly, but about 9% more than for Xenoposeidon. Oddly enough, for this blog, the two most informative elements are appendicular: a nearly complete and very weird left ilium, and most of a very nice and rather weird left scapula. We also have a single badly mangled presacral centrum (though even that is interesting), a single gorgeous and (you guessed it) weird caudal vertebra, a pair of partial sternal plates, and a bunch of dorsal ribs in various states of repair, of which one, probably the first from the right-hand side, is complete and — you guessed it — weird. (No cervical ribs, though.) There are a few more fragments, but they’re uninformative.
We know that not all this material is from a singe animal, because it’s of wildly different sizes: based on the relative sizes of scapula and ilium in Rapetosaurus, we estimated that the animal that contributed the scapula is about three times as long in linear dimension (and so about 3^3 = 27 times as massive) as the much smaller beast that kindly donated its ilium. “But wait!”, you cry: “If the bones are not all from the same individual, what makes you say they’re all from the same taxon?” Patience, young padawan; we will discuss this at length later this week (hereafter PYP;WWDTALLTW).
Because the ilium is the most distinctive of the bones, we nominated it as the holotype. “But wait!”, you cry: “If the ilium is from a juvenile individual, surely it’s not suitable to be the holotype?” PYP;WWDTALLTW.
We diagnosed Brontomerus by five autapomorphies of the holotype ilium: preacetabular lobe 55% of total ilium length, longer than in any other sauropod; preacetabular lobe directed anterolaterally at 30° to the sagittal, but straight in dorsal view and vertically oriented; postacetabular lobe reduced to near absence; ischiadic peduncle reduced to very low bulge; ilium proportionally taller than in any other sauropod, 52% as high as long. What does all that mean? PYP;WWDTALLTW. (Wow, that acronym is turning out to be more useful than I expected.) In briefest summary, it’s nothing like any other sauropod ilium I’ve ever seen; and that’s not because it’s from a juvenile.
Brontomerus has had a slightly odd publication history: it was inadvertently published as an “accepted manuscript” on the Acta web-site on 3rd January, whence it was quickly picked up by the Dinosaur Mailing List. In a matter of hours, a Wikipedia article appeared, along with mentions on a surprising number of web-sites: as I write this, four days before publication, Google has 60 hits for “brontomerus” including pages from Germany, Holland, the Czech Republic, Poland and Argentina. But the Acta people were very fast to take down the accepted manuscript once I’d pointed out that the name was being accidentally leaked, and I was able to have the Wikipedia article deleted pretty quickly too. It seems that, against all expectation, the genie was pretty much put back in the bottle.
As if that weren’t enough failage to be going on with, I (Mike) accidentally posted this very article a couple of days before publication. D’oh! (WordPress’s Publish button is terribly easy to hit.) Again, we scrambled to try to limit the damage. I was able to un-publish the article itself, but by then it had already gone out by RSS, so some of you might have seen this post before in that earlier form. (This is of course the reason for the I’m Stupid post.)
All the rushing around to shut down premature announcements was, of course, indended to keep the powder dry for today; and we heartily encourage all of you who’ve been wanting to to talk about Brontomerus to do so now!
There is a lot more that we could say — and will say — about Brontomerus. We have a bunch more posts planned for later in the week, as noted above. Those of you who can’t wait will of course read the paper, but may also find yummies on the press-pack page or the unofficial online supplementary information.