When I started this series, it wasn’t going to be a series at all. I thought it was going to be a single post, hence the title that refers to all three of Jensen’s 1985 sauropods even though most of the posts so far have been only about Supersaurus. The tale seems to have grown in the telling. But we really are getting towards the end now. This should be the last post that is only about Supersaurus, and then we should be able to finish with one more that covers all three animals.

Supersaurus skeletal reconstruction at NAMAL, based in part on preserved fossil material. Mike Taylor for scale, lying in front of the referred scapulocoracoid BYU 12962.

So: what actually is Supersaurus?

Is Supersaurus the same thing as Barosaurus?

As we established previously, a lot of material has been referred not only to Supersaurus in general, but to the type individual in particular: a cervical, two dorsals, four sacrals, 20 caudals, two scapulocoracoids, an ulna, a carpal, right ilium and pubis, both ischia, and a phalanx. (After Jensen’s original papers, Curtice and his collaborators did much of the work to assemble this list.) And remember, too, that Lovelace et al. (2008) described a completely separate Supersaurus specimen from Wyoming.

So: a problem arises: Matt and I are about as certain as we can be that the big cervical verebra BYU 9024 is Barosaurus. That means there are two possibilities: either the cervical been wrongly referred to the Supersaurus type individual, and our conception of Supersaurus needs to change accordingly; or it was correctly referred, which means that Supersaurus is merely a very big Barosaurus, and the name should be sunk.

I would be a lot more confident about which of these is the right thing to do if Matt and I had had time to look at all the sacral, caudal and appendicular material of Supersaurus during the Sauropocalypse. But our time was very limited (seven museums in nine days) and we had to focus on the presacrals.

What we really want is a solid assessment of all the putative Supersaurus material and a judgement of whether the differences between it and regular Barosaurus might be size- or age-related. We can’t have that (at least, not unless someone with more time on their hands than Matt or me takes it on).

But we are not left without hope. We have the published literature.

Pylogenetic analyses

Lovelace et al. (2008:figure 14). Strict consensus tree resulting from the addition of Supersaurus and “Seismosaurus” into a modified matrix from Harris & Dodson (2004).

First, Lovelace et. al’s (2008) description of Jimbo, the WDC’s referred Supersaurus specimen, included a phylogenetic analysis. This recovered Supersaurus as the sister taxon to Apatosaurus, with Suuwassea as its outgroup, and the BarosaurusDiplodocus clade sister to that broader grouping. That finding would argue against Supersaurus being Barosaurus. (They commented that “It is possible that some similarities between Supersaurus and other apatosaurines result from a size-coupled increase in robustness, but it is worth noting that apatosaurine robustness does not correlate with size, and large diplodocines like Seismosaurus do not exhibit markedly more robust pelvic or costal elements.)

Whitlock (2011:figure 7). Phylogenetic hypothesis presented in this analysis. Cladogram represents a strict consensus of three equally parsimonious trees (273 steps), labelled with relevant clade names. Decay indices reported below each node.

Whitlock’s (2011) more detailed phylogenetic analysis recovered Supersaurus is a somewhat more traditional position, closer to Barosaurus than to Apatosaurus. But still not very close. Supersaurus is here the most basal diplodocine, the outgroup to Dinheirosaurus, Torneria and the Barosaurus+Diplodocus pair. It’s not a result that would immediately make you want to synonymise Supersaurus with Barosaurus.

One problem with both Lovelace et al.’s and Whitlock’s analyses is that they took as read that the WDC specimen really is Supersaurus — the same thing as the BYU specimen. What if it isn’t? Maybe the WDC animal is something different that’s more closely related to Apatosaurus, while the BYU specimen is a big Barosaurus? Is that possible?

Enter Tschopp et al. (2015), whose monumental specimen-level analysis separated Jimbo out from BYU Supersaurus — and so they tested the hypothesis that these two specimens are the same thing, instead of assuming it. Here’s what they found:

Tschopp et al. (2015:figure 118). Reduced consensus tree obtained by implied weighting. Eight OTUs were deleted a posteriori. Numbers at the nodes indicate the number of changes between the two branches departing from the node (for the apomorphy count), where they differ from the trees under equal weights.

As you can see, BYU Supersaurus and the WDC specimen came out as sister taxa in every most parsimonious tree. And Tschopp et al.’s (2015) figure 115 shows that this is true under equal-weights parsimony as well as under implied weighting. So this gives us confidence that the WDC team’s referral of Jimbo to Supersaurus probably is correct after all.

But that Supersaurus duo comes out some way away from Barosaurus, being well outside the DiplodocusBarosaurus node.

These are the only three phylogenetic analyses I am aware of to have included Supersaurus — though if there are others, please shout in the comments. In none of them do Supersaurus and Barosaurus come out as sister taxa, and in fact they are separated by multiple nodes in all three analyses.

Is BYU Supersaurus a chimaera?

All of this strongly suggests — though it doesn’t conclusively prove — that Supersaurus (as defined by all the BYU and WDC material) is not Barosaurus. But if Matt and I are right that BYU 9024 is a vertebra of Barosaurus, then it follows that this cervical doesn’t belong to Supersaurus.

And that, I think, throws the whole material list of BYU Supersaurus into question. Because if the big cervical belongs to something different, then it follows that there are (at least) two big diplodocids mixed up in the Dry Mesa quarry, contra Curtice et al.’s (2002) assertion that all the big bones there can be referred to two individuals, one diplodocid and one brachiosaur.

In which case, how can we know which of the elements belongs to which of the animals?

Are the scapulocoracoids from the same individual?

Can we even trust the assumption that the two scapulocoracoids were from the same animal? Maybe not. In favour of that possibility, the two elements are similar sizes, and were found close together. But there are reasons to be sceptical.

Based on our photos in the earlier post, I was coming to the conclusion that Scap B is much less sculpted than Scap A. But I started to change my mind once I was able to make a weak anaglyph of Scap B. Now, thanks to Heinrich Mallison and the magic of photogrammetry, my set of bad photos have become a 3D model, which is far more informative again.

Here, then, is a comparative anaglyph of the two scapulocoracoids.

Red-cyan anaglyps of both scapulocoracoids of Supersaurus from BYU’s Dry Mesa Quarry, Utah. Top: the holotype BYU 9025, left scapulocoracoid (“Scap A”); Bottom: referred specimen BYU 12962, right scapulocoracoid (“Scap B”), reversed for easier comparison. Scap B rendered from a 3D model created by Heinrich Mallison. Scaled to the same length. (We could not scale them in correct proportion, since the true current lengths of both are unknown.)

These are not obviously from the same individual, or from the same species, or even necessarily the same “subfamily”. A few of the more obvious morphological differences:

  • In Scap A, the acromion process projects posterodorsosally, whereas in Scap B it projects dorsally (i.e. at right angles to the long axis of the scap.)
  • In Scap A, the acromion process is positioned close to mid-length of the whole element, whereas in Scap B it is closer to the proximal end.
  • In Scap A, the acromion process comes to a point, whereas in Scap B is it lobe-shaped.
  • In Scap A, the ridge running running up to the acromion process is broad and becomes rugose dorsally, whereas in Scap B it is narrow and remains smooth along its whole length.
  • Scap B has a distinct ventral bump around midlength, which Scap A lacks (or at most has in a much reduced form).
  • In Scap B, the ventral border below the acromion process distinctly curves down to the glenoid, but in Scap B this ventral margin is almost straight.
  • In Scap A, the glenoid margin is gently curved, nearly straight, whereas in Scap B it has a well defined “corner”, with distinct scapular and coracoid contributions that are at right angles to each other.
  • In Scap A, the dorsal margin of the coracoid is well defined and has a low laterally protruding ridge. This is absent in Scap B, where the coracoid’s dorsal margin is poorly defined.

Now, much of this is quite possibly due to damage — as (I assume) is the excavation in the dorsal margin of the distal part of the scapular blade in Scap A. But when you put it all together, I think they really are rather different, even allowing for variation in limb-girdle bones. Certainly if you found them both in different quarries, you would not leap to the conclusion that they belong to the same species. Jensen’s (1985:701) description of Scap B (BYU 5001 of his usage) as “same as Holotype, BYU 5500” is difficult to justify.

The possibility that the two scaps are from different individuals is also weakly supported by the fact that the preservation looks very different between the two elements — dark and rough for Scap A but light and smooth for Scap B. But I don’t trust that line of evidence as much as I might for two reasons. First, different photography conditions can give strikingly different coloured casts to photos, making similar bones appear different. And second, I know from experience that bones from a single specimen can vary in colour and preservation much more than you’d expect.

At any rate, I certainly don’t think it’s a given that the two scapulae belonged to to the same individual as Curtice and Stadtman (2002) stated. And of course if they do not, then the issue of which is the holotype takes on greater importance — which is why we spent so long on figuring that out.

So what are we left with?

We know — or at least we are confident — that one of the referred BYU Supersaurus elements is Barosaurus. We don’t think the whole animal is Barosaurus, due to the evidence of three phylogenetic analyses. So we think there are at least two big diplodocoids in the BYU quarry, and we can’t know which of the elements belongs to which animal. We can’t even be confident that the two scapulocoracoids belong to the same animal.

As a result, the only bone that we can confidently state belongs to Supersaurus is the holotype — BYU 9025, which we called “Scap A”. All bets are off regarding all the other Dry Mesa diplodocoid elements. They might belong the Scap A taxon, or to Barosaurus. (Or indeed to something else, but we’ll ignore that possibility as multiplying entities without necessity.)

So to the next question: is the holotype element even diagnostic, beyond the level of “big diplodocoid”? I’m not sure it is, but this is where I’d welcome input from people who are more familiar with sauropod appendicular material than I am. At any rate, Jensen’s (1985:701) original diagnosis based on the holotype scap is useless: “Scapula long but not robust; distal end expanding moderately; shaft not severely constricted in midsection”.

The emended diagnosis of Lovelace et al. (2008:530) says of the scapulocoracoid only “scapular blade expanded dorsally; deltoid ridge perpendicular to the acromian[sic] ridge”. but they also include a more comprehensive assessment of the BYU scapulae (p. 534) as follows:

The only known pectoral elements for Supersaurus are the scapulocoracoids from Dry Mesa (Fig.10). Scapulocoracoid BYU 9025 demonstrates a deltoid ridge that is perpendicular to the acromian ridge and the scapular blade is one-half the entire length of the scapulocoracoid. Both of these features are seen in Apatosaurus but not in Diplodocus or Barosaurus, which have relatively short scapular blades, and an acute angle between the deltoid ridge and the acromian ridge. This angle is much stronger in Barosaurus than it is in Diplodocus. The apatosaurine nature of the scapulocoracoids further reinforces the referral of BYU elements to the type scapula, as well as our referral of WDC DMJ-021 to Supersaurus.

This is a helpful discussion (although note that Lovelace et al. are not consistent about which of the scaps they think is BYU 9025). But, notably, nothing here suggests any unique characters of the scapulocoracoid that could serve to diagnose Supersaurus by its holotype.

Putting it all together, it seems that BYU 9025 is the only bone in the world that unambiguously belongs to Supersaurus (because it is the the holotype, and all referrals are uncertain); and that bone is non-diagnostic. I think it must follow, then, that Supersaurus is currently a nomen dubium.

I say “currently”, because there are at least three possible ways for the name to survive. (Four, if you count everyone just ignoring this sequence of blog-posts.) Next time, we’ll talk about those options.

 

References

  • Curtice, Brian D. and Kenneth L. Stadtman. 2002. The demise of Dystylosaurus edwini and a revision of Supersaurus vivianae. Western Association of Vertebrate Paleontologists and Mesa Southwest Museum and Southwest Paleontologists Symposium, Bulletin 8:33-40.
  • Harris, Jerald D., and Peter Dodson. 2004. A new diplodocoid sauropod dinosaur from the Upper Jurassic Morrison Formation of Montana, USA. Acta Palaeontologica Polonica 49:197–210.
  • Jensen, James A. 1985. Three new sauropod dinosaurs from the Upper Jurassic of Colorado. Great Basin Naturalist 45(4):697–709.
  • Lovelace, David M., Scott A. Hartman and William R. Wahl. 2008. Morphology of a specimen of Supersaurus (Dinosauria, Sauropoda) from the Morrison Formation of Wyoming, and a re-evaluation of diplodocid phylogeny. Arquivos do Museu Nacional, Rio de Janeiro 65(4):527–544.
  • Tschopp, Emanuel, Octávio Mateus and Roger B. J. Benson. 2015. A specimen-level phylogenetic analysis and taxonomic revision of Diplodocidae (Dinosauria, Sauropoda). PeerJ 2:e857. doi:10.7717/peerj.857
  • Whitlock, John A. 2011. A phylogenetic analysis of Diplodocoidea (Saurischia: Sauropoda). Zoological Journal of the Linnean Society 161(4):872-915. doi:10.1111/j.1096-3642.2010.00665.x

 

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Before we get on to the home stretch of this series — which is turning out waaay longer than I expected it to be, and which I guess should really have been a paper instead — we need to resolve an important detail. We all know there are two scapulocoracoids in the BYU Supersaurus material, and that one of them is the holotype: but which one?

The two elements

Since we don’t know the actual specimen numbers yet, we’ll refer to the two specimens as Scap A and Scap B for now.

Both specimens are on loan from BYU to other museums. Scap A is at the Dinosaur Journey Paleontological Museum in Fruita, Colorado; and Scap B is at the North American Museum of Ancient Life (NAMAL) in Lehi, Utah. Happily, we saw both on the Sauropopcalypse. Unhappily, we were in a rush both times, and didn’t pay them anything like the attention they deserve.

Scap A

We don’t have many photos of this, because we only had a single day at Dinosaur Journey museum and we had a lot of specimens we wanted to hit in collections. But it’s still shameful that we have as little as we do. Here’s one from Matt’s earlier visit in 2014:

One of the scapulocoracoids of Supersaurus, which we here refer to as Scap A, at the Dinosaur Journey musuem in Fruita, Colorado. Matt Wedel for scale.

And here is an anaglyph made from the only two photos I took on our 2016 Sauropocalypse visit:

Sort-of-OK anaglyph of the Supersaurus scapulocoracoid A. It’s not great because we don’t have a good pair of source photos, but it’s still way more informative than a 2d photograph.

If you think our photos are disappointing, check out Jensen’s own illustrations of this specimen. It crops up in line-drawing form as part B of figure 8 in his 1985 paper:

Jensen 1985:figure 8B and G. For comparison only, not to scale. Profiles of various sauropod scapulae and scapulocoracoidae. B, Supersaurus vivianae, first specimen. G, Supersaurus vivianae, second specimen. (Other, non-Supersaurus, parts removed.)

And that seems to be all we have of this specimen.

Well … almost all. There is just one other photo …

I really really wish I’d spent less time making out with this specimen and more time studying it. There’s a lesson there for all of us, kids!

This scap has really nice, clear ridges running along the ventral border of the proximal end, and up from there to the acromion process. That makes it very clear that we’re looking at the lateral side of the scap, which means it’s a left scapulocoracoid.

By the way, I am a little short of six feet tall. Using myself as a very crude scalebar, it looks like this scap is a hair over eight feet long. (Why am I using Imperial measurements? Because, as will become clear below, that’s what Jensen used, and so what we want to compare with.)

Scap B

This occurs in Jensen’s (1985:figure 8G) line drawing, as shown above. But there are a few more photos out there. For a start, this is the scap which Jensen is measuring and then lying next to in the photos in his descriptive paper:

Jensen 1985:figure 6. A, Measuring Supersaurus vivinae scapulocoracoid. D. E., Vivian Jones; J. A. Jensen. B, The author, 6’3″ tall beside Supersaurus vivianae scapulocoracoid.

This is evidently the scap that we photographed at NAMAL, although it’s been flipped since the photos were taken of it in the ground:

Supersaurus vivianae scapulocoracoid, photographed at the North American Museum of Natural Life. The exhibit text reads: “Supersaurus scapula and coracoid. This is the actual Supersaurus bone that the world saw when the announcement was made of the new animal’s discovery in 1972. The scapula lay in the ground for five more years, waiting for the collection of other fossils that lay in the path of excavation. The flatness of the bone presented a challenge to “Dinosaur Jim” Jensen, who had to figure out a way to get the bone safely out of the ground. He finally accomplished this by cutting the scapula into three pieces. In 1988, Cliff Miles, Brian Versey and Clark Miles prepared the bone for study. It is still one of the largest dinosaur bones known in the world. Specimen on load from Brigham Young University’s Earth Science Museum. Late Jurassic/Early Cretaceous (about 144 million years ago)

A similar photo turns up in Lovelace et al.’s (2008) description of the WDC Supersarus specimen, where a specimen number is given. This is welcome, as neither museum display includes a specimen number, and none of the Jensen’s illustrations do, either. It’s the first specimen number we’ve seen in this post.

Lovelace et al. 2008:figure 10. Lateral view of Supersaurus right scapulacoracoid (BYU 9025).

Also, Lovelace et al. (2008) provided a scalebar. If it’s reliable — which is always open to question with scalebars — the scapulocoracoid is 2.34 m long (based on 687 pixels for the scap, 147 for the scalebar), which is about 7’8″.

I don’t know where Lovelace et al. got the specimen number for this element: it’s certainly not on display in the NAMAL public gallery. Elsewhere, Lovelace et al. (2008:527) say that “The name Supersaurus was erected for a single scapulocoracoid, BYU 12962″, contradicting Jensen’s designation of BYU 5500 (i.e. BYU 9025) as the holotype.

Is this in fact a right scapulocoracoid, as claimed? I did wonder, because based on my own photos and the Lovelace et al. illustration the surface we’re looking at is pretty flat and featureless, which would suggest it’s the medial side of the bone. If that were so, it would be a left scap viewed from inside, not a right scap viewed from outside. But I was able to recover a very rough-and-ready anagylph from my NAMAL photos, and that was enough to persuade me that there is some surface structure on this bone, and that we are indeed therefore looking at the lateral face of a right scap.

(If you can’t make out the 3d structure here, it’s because you don’t have any red-cyan anaglyph glasses. Get some red-cyan anaglyph glasses. You’ll thank me.)

Anyway: I am satisfied that Scap A is a left scapulocoracoid and Scap B is right scapulocoracoid. So that’s something.

Which is the holotype?

This should be a simple question to resolve. But it’s not, for several reasons. First, although the earliest literature on Supersaurus refers to the scapulocoracoids, it doesn’t give specimen numbers. Second, Jensen’s (1985) description is vague about specimen numbers, sometimes using them and sometimes just referring to “first specimen” and “second specimen”. Third, the specimen numbers that Jensen used have since been changed. Fourth, the subsequent literature contains contradictions and perhaps straight-up mistakes. And finally, as though all that were not enough — and as we’ve already noted — the two museums that have the actual bones on display have omitted specimen numbers from their signage.

Yeah. It’s pretty crazy stuff. Let’s see if we can sort it out.

That Reader’s Digest article

The earliest reference to the name “Supersaurus” we’ve been able to find in the literature is George 1973b. (This predates George 1973c, cited by Curtice and Stadtman 2002, which I have been unable to obtain a copy of, if indeed it is actually a real article, as it does not seem to be. I also have not been able to obtain George 1973a, which the 1973b article is a condensation of. If anyone can help me with either of these, I would appreciate it!)

Aaanyway, here’s what George (1973b) says about “Supersaurus” scapulae. It doesn’t amount to much.

A shoulder blade, still partially encased in clay, spanned eight feet. Breaks and cracks were sealed with a mixture of sand and plaster, the bones were wrapped in burlap soaked with plaster of paris, braced, then swung aboard a special trailer for the journey to B.Y.U. in Provo, Utah. There, “Supersaurus,” as we shall call him, awaits an official name and taxonomic classification.

This certainly sounds like the eight-foot-long scap was destined to be the type specmen, but it doesn’t come out and say it.

Jensen 1985

As far as I know, the next published reference to this material is eight full years later, in Jensen’s (1985) formal description. It needs careful reading. But what seems clear (from page 701) is:

HOLOTYPE.—BYU 5500, scapulocoracoid 2.44m (8′) long.

REFERRED MATERIAL.—BYU 5501, scapulocoracoid 2.70 m (8′ 10″) long. [And other material not of interest for our purposes.]

[… and a little later …]

DESCRIPTION.—(Holotype BYU 5500; right scapulocoracoid) Scapula long but not robust; distal end expanding moderately; shaft not severely constricted in midsection. [There is more, but it’s not relevant here]

REFERRED MATERIAL.—BYU 5501, scapulocoracoid 2.70 m (8′ 10″) long. Description same as Holotype, BYU 5500.

So based on this, the “description” of the two scaps is the same, and the only recognised difference is in length: the holotype, at eight feet in length, is ten inches shorter than the referred element.

On that basis, Scap B might seem the more likely contender to be the holotype, as the scalebar in Lovelace et al. 2008:figure 10 suggests a length of 2.33 m which is closer to the 2.44 m given for the type than to the 2.7 m given for the referred specimen.

(On the other hand, the photo of me in love with Scap A at Dinosaur Journal suggests it’s about eight feet long, which would mean that it might be the type. *sigh*)

As we have seen, the captions in Jensen 1985 do not give specimen numbers, so we can’t tell whether the scap in his figure 6 is the holotype. And in the comparative figure 8 which shows both scaps, he maddeningly calls them “first specimen” and “second specimen” instead of giving numbers. We might guess that “first specimen” is the type; but it might instead refer to the order in which they were found or excavated. And we might guess that the specimen appearing in Jensen’s photos is the type, but it really would only be a guess — and one contradicted by the guess based on “first specimen”, since the photographed bone is the “second specimen”.

Jensen 1987

Jensen’s 1987 paper is primarily about brachiosaur material, but it does contain information relevant to to the present problem. Its figure 9 replicates Jensen 1985:figure 8 (the comparaive scapula line-drawings) but with an even less informative caption that doesn’t even say “first specimen” or “second specimen” for the two Supersaurus scaps. But then the text on page 602 may contain a key bit of information, given away in passing as though by accident:

I here remove the vertebra, BYU 5003, from Brachiosauridae and provisionally refer it to the Diplodocidae. This referral is based on two factors: principally, a bifurcate neural spine, and, secondly, the fact that two unusually large scapulocoracoids (Figs. 9B, 9G), found in the same (Dry Mesa) quarry, were referable to the Diplodocidae. One of these (BYU 5500, Fig. 9B) is the holotype of Supersaurus vivianae Jensen (1985).

Astonishingly, this is the first time in any of Jensen’s papers that he associates a specimen number with an illustration of either of the Supersaurus scaps. Jensen was notoriously careless with specimen numbers, but BYU 5500 does match his designation of the holotype in his 1985 paper, so we can perhaps be somewhat confident in this case.

The old specimen number BYU 5500 corresponds with the new number BYU 9025, which suggests that BYU 9025 is the the scap illustrated in Jensen 1987:figure 9B — which is scap A.

Curtice and Stadtman 2002

Curtice et al.’s (1996) paper referring the Ultrasauros holotype dorsal vertebra to Supersaurus does not say anything about the two Supersaurus scapulae. But the followup paper on Dystylosaurus (Curtice and Stadtman 2002) does. As noted in part 3 of this series, the “Supersaurus vivianae roll call” section remarks:

When [Supersaurus was] formally described (Jensen, 1985) a number of elements were referred to the holotype including the left scapulocoracoid discovered in 1972 (BYU 9025), a right scapulocoracoid (BYU 12962) …

This is not as helpful as it could be, as it lists both scapulae as “referred” without stating explicitly which was the holotype. But based on the evidence so far, we can be fairly confident that it it really was BYU 9025 (BYU 5500 of Jensen’s usage). The really useful information here is the designation that 9025 is a left scap and 12962 is the right. Since scap A is clearly left sided, this offers corroboration that is is the holotype, BYU 9025.

As we discussed before, Curtice and Stadtman (2002:39) went on to say:

Jensen never referred the two Supersaurus scapulocoracoids to the same individual due to a 260 mm discrepancy in length. Stripping away the paint and resin on BYU 9025 revealed the proximal end had been inadvertently lengthened during preservation. Close examination of the actual bone surface nets a total scapulocoracoid length less than 50 mm longer than BYU 12962, an amount easily accounted for by scapular variation and thus here both are referred to the same individual.

But this doesn’t make sense for two reasons. Most importantly, BYU 9025 is BYU 5500 of Jensen’s usage, and his 1985 paper makes it clear that this was the shorter of the two scaps at 8 feet, compared with 8 feet 10 inches for his BYU 5501 (i.e. BYU 12962). Shortening BYU 9025 would increase the discrepancy in length between the two scaps, not decrease it. Perhaps Curtice and Stadtman got the two scapulocoracoids’ specimen numbers reversed?

It’s also surprising because of the claim that the it was the proximal end that was inadvertently lengthened. The proximal end of a scapulocoracoid is the coracoid bone, which is thick and sturdy, and has a well defined proximal margin that would be difficult to inadvertently lengthen. Whereas the distal end — the farthest part of the scapula blade — is thinner and easily broken, and potentially shades into cartilage where the cartilaginous suprascapula attached. We could easily imagine the latter being subject to interpretation, but not really the proximal end. Perhaps Curtice and Stadtman (2002) were using the terms “proximal” and “distal” in the opposite sense to how they are generall applied to scapulae?

Dale McInnes’s involvement in preparation

In a comment on the first post in this series, Dale McInnes took issue with aspects of Curtice and Stadtman’s account of the repreparation of the scaps. According to McInnes, Jensen sent “the second specimen” (i.e. what we’re calling Scap B, if the caption to Jensen 1985:figure 9 is to be trusted) to RAM, and Phil Currie had McInnes prepare it in the late 1970s (i.e. after the initial popular publications on “Supersaurus” but well before Jensen’s formal publication in 1985). In an 11-foot-long field jacket, they found 9’2 of bone, which they reduced to 8’10 by closing four inches of open cracks.

So far, this account is consistent with that of Jensen (1985), who quotes only the final prepared length of 8’10”. But it doesn’t help us to make sense of Curtice and Stadtman’s account of re-preparing BYU 9025 to reduce its length, thereby creating a larger gap between its length and that of BYU 12962.

If Curtice and Stadtman were here reporting on the wrong scapula (i.e. they “stripped away the paint and resin” from BYU 12962) then it seems they may have undone some of the careful work done by McInnes and colleagues to preserve “an area that had an ultra thin section that at best could only be described as a sharply defined delineation of the distal termination (literally powdered bone) [which might have been] an imprint of the cartilage”. If so, that is unfortunate indeed.

So which is which?

Jensen 1985 designated BYU 5500 (= BYU 9025) as the holotype and said it was 2.44 m (8′) long. He referred BYU 5501 (= BYU 12962) and said it was 8’10” long — but neither scap in its present form seems to be longer than 8′, so the differences in length reported by Jensen don’t help much.

Scap A (at the Dinosaur Journey Paleontological Museum in Fruita, Colorado) is a left scapulocoracoid. Curtice and Stadtman (2002) noted that BYU 9025 is a left scap (and BYU 12962 is a right scap), so that suggests that Scap A is BYU 9025.

Scap B (at the North American Museum of Ancient Life in Lehi, Utah) is a right scapulocoracoid, maybe 2.34 m long (7 feet 8 inches), based on the scale bar from Lovelace et al. (2008:figure 10). Their caption for that figure says it’s BYU 9025, but elsewhere they claim (incorrectly as far as I can tell) that BYU 12962 is the holotype, so something is wrong there.

The single most helpful thing in the literature is Jensen’s (1987:602) almost parenthetical comment that “(BYU 5500, Fig. 9B) is the holotype of Supersaurus vivianae“, as it’s the only published work that ties any specimen number to any illustration. Figure 9b shows Scap A — which indeed seems to be about eight feet long, according to the very fallible Mike-as-scalebar method.

But Curtice and Stadtman’s (2002:39) comments on re-prepping BYU 9025 suggest that it is the longer of the two elements, and  therefore (according to Jensen’s 1985 description) the referred element and not the holotype. We know that one of the scaps at least at one time measured 8’10, becausde of McInnes’s account of reducing the length of “the second specimen” to 8’10. But neither of them presently seems to be that long. (I hope Dale comments again, on this post, and is able to tell us whether the bone her worked on was Scap A or Scap B — and whether its present state is different from how he left it.)

Putting it all together, I think the weight of evidence says that Scap A is the holotype (BYU 9025, previously known as BYU 5500), with Jensen’s (1987:603) comment being our smoking gun. Other evidence includes Curtice and Stadtman’s (2002) observation that BYU 9025 is a left scap; its being about the right length (I trust my own scalebar, however informal, ahead of Lovelace et al.’s); and the fact that it is the better preserved of the two elements, making it a stronger candidate for having been selected as the holotype.

If that’s correct, then it is not without problems. It would follow that Lovelace et al. (2008:figure 10) is miscaptioned, being BYU 12962 and not 9025 as stated. It would also follow that Curtice and Stadtman were in error in describing the re-preparation of what was in fact the referred specimen BYU 12962 and not 9025 as stated.

Addendum: a cautionary tale

When I started this series of articles, I assumed that the NAMAL scap was the holotype (as you can see in the caption for the illustration of it in the first article). Why did I think that? Well, the Wikipedia article [archived link] says so: it has a photo of it captioned “The holotype of Supersaurus, scapulocoracoid BYU 9025″.

But as I got deeper into writing this series, I checked out the provenance of that photo on Wikipedia, only to find that it’s my own photo, as edited by Stephen O’Connor. Then I checked my emails to see whether I’d ever corresponded with Stephen, and I found that he’d emailed me three years ago including a link to this old SV-POW! photo of Scap A, and asking “I’m a little confused if the scapular in the image is a cast of holotype BYU 9025 or is it the opposing side, BYU 12962?” And I replied as follows:

Hi, Steve. I am attaching Jensen 1985, which is the canonical reference for this. Very poorly illustrated, though […]. Based on Figure 8 (page 708), the photo is a cast of “second specimen”. I’m attaching my photo of the holotype (“first specimen”) at NAMAL in Utah, in case it’s helpful.

So what happened here is that I over-interpreted a vague bit of hand-waving in Jensen 1985, fed it via Steve into Wikipedia, then trusted my own forgotten authority to reinforce the apparent legitimacy of my incorrect guess. I trusted Wikipedia on the identity of the NAMAL scap only to find it was my own assumption fed back to me.

A couple of days ago I read “Ninety percent of online journalism these days is nothing more than wannabe reporters summarizing other people’s assumptions from web sites that know how to game a search engine”.  I am pleased to find that I am efficient enough to cut out the wannae-reporter middle man from this process, and just summarise my own assumptions.

 

References

  • Curtice, Brian D. and Kenneth L. Stadtman. 2002. The demise of Dystylosaurus edwini and a revision of Supersaurus vivianae. Western Association of Vertebrate Paleontologists and Mesa Southwest Museum and Southwest Paleontologists Symposium, Bulletin 8:33-40.
  • Curtice, Brian D., Kenneth L. Stadtman and Linda J. Curtice. 1996. A reassessment of Ultrasauros macintoshi (Jensen, 1985). M. Morales (ed.), “The continental Jurassic”. Museum of Northern Arizona Bulletin 60:87–95.
  • George, Jean. 1973a. Supersaurus, the biggest brute ever. Denver Post, Empire Magazine. May 13, 1973.
  • George, Jean. 1973b. Supersaurus, the biggest brute ever. Reader’s Digest (June 1973):51–56.
  • George, Jean. 1973b. Supersaurus, the greatest of them all. Readers Digest (August 1973), page-range unknown.
  • Jensen, James A. 1985. Three new sauropod dinosaurs from the Upper Jurassic of Colorado. Great Basin Naturalist 45(4):697–709.
  • Jensen, James A. 1987. New brachiosaur material from the Late Jurassic of Utah and Colorado. Great Basin Naturalist 47(4):592–608.
  • Lovelace, David M., Scott A. Hartman and William R. Wahl. 2008. Morphology of a specimen of Supersaurus (Dinosauria, Sauropoda) from the Morrison Formation of Wyoming, and a re-evaluation of diplodocid phylogeny. Arquivos do Museu Nacional, Rio de Janeiro 65(4):527–544.

 

It’s time to revisit everyone’s favourite trio of apocryphal super-sized sauropods! (Yes, we’ve talked about this before, but only very briefly, and that was nearly eleven years ago. Things have moved on since then.)

John Sibbick’s classic artwork showing three giant sauropods, including two of Jensen’s three. On the left is Seismosaurus Gillette 1991, which is not directly relevant to today’s post. In the middle is the brachiosaur Ultrasaurus, and on the right the diplodocid Supersaurus. Poor, unloved Dystylosaurus doesn’t get a look-in — perhaps because this was drawn before that name had been announced?

Here’s the story so far …

1. Jensen’s discoveries

In a series of expeditions beginning in April 1972, following a tip from uranium prospectors Eddie and Vivian Jones, Jim Jensen found numerous massive sauropod fossils in the Dry Mesa quarry, southwest Colorado. The Supersaurus pelvis at least was still in the ground as late as August 1972 (George 1973b:51–52) and the excavations continued into 1982 (Jensen 1985:697).

Eschewing such pedestrian venues as Science, Nature or indeed the Journal of Vertebrate Paleontology, Jensen first told the world about these finds in the popular press. The oldest published work I have that mentions them is Jean George’s (1973b) piece in Reader’s Digest, condensed from the same author’s piece in the Denver Post’s Empire Magazine earlier that year (George 1973a), which I have not been able to obtain.

“‘Supersaurus,’ as we shall call him, now awaits an official name and taxonomic classification”, wrote George (1973b:53) — but the piece does not mention the names “Ultrasaurus” or “Dystylosaurus” and I’ve not been able to determine when those informal names became known to the world. (Can anyone help?) We do know that Jensen was informally using the name “Ultrasaurus” as early as 1979 (Curtice et al. 1996:87).

Anyway, for reasons that have never been very clear, Jensen concluded that the remains represented not one, not two, but three gigantic new genera: a diplodocid, which he named “Supersaurus”; a brachiosaurid, which he named “Ultrasaurus”; and an unidentifiable which he named “Dystylosaurus”. All these names were informal at this point, like “Angloposeidon” and “The Archbishop”.

2. Kim’s accidental Ultrasaurus

After Jensen had been using these names informally for some years, Kim (1983) named an indeterminate Korean sauropod as Ultrasaurus tabriensis. Based on the abstract (the only part of the paper in English, apart from the figure captions), Kim was aware of Jensen’s dinosaurs: “Judging by the large size of the ulna the animal may belong to the sauropod dinosaur, which is much bigger than Supersaurus. A new name Ultrasaurus tabriensis is proposed for the convenience of the further study.” While this does not quite go so far as to say that Kim considered the ulna to belong to the same genus as Jensen’s brachiosaur, it seems unlikely that he was aware of Supersaurus but not of Ultrasaurus, and landed independently on the latter name by coincidence.

Either way, in naming his species, Kim inadvertently preoccupied Jensen’s chosen genus name, with conseqences that we shall see below. By all accounts, the material the Kim described is in any case indeterminate, and the genus is generally considered a nomen nudum (e.g. Olshevsky 1991:139, Glut 1997:1001).

Kim 1983, plate 1, parts 1-3, illustrating the proximal portion of the huge “ulna” that the name Ultrasaurus tabriensis was founded on. As is apparent, this is actually the proximal end of a humerus, meaning that the animal is rather less large than Kim supposed — although the 42 cm width across the proximal end is still nothing to be sniffed at. It is about 71% the width of the 59 cm-wide humerus of the Giraffatitan brancai paralectotype MB.R.2181 (previously HMN SII).

Two years after this, and presumably unaware of Kim’s paper or incorrectly assuming his informal use of the name “Ultrasaurus” gave him priority, Jensen published a formal account of his finds, naming them (Jensen 1985). Unfortunately, while the paper does contain formal nomenclatural acts that are valid according to the rules of the ICZN, Jensen did not explain his reasoning for the creation of the new genera, and his selection of type material was problematic, as we shall see below. Also, the specimen numbers that he used have been superseded — I do not know why, but my guess would be that he re-used numbers that were already in use for other specimens, so his own material had to be given new numbers.

3. Jensen’s three sauropods

The following three genera (with their type species) were named, in this order:

1. Supersaurus vivianae, based on the holotype BYU 9025 (BYU 5500 of his usage), a scapulocoracoid measuring 2.44 m in length. To this, he referred an even larger scapulocoracoid whose length he gives as 2.70 m (though Curtice and Stadtman 2002:39 found that this length to be due to optimistic reconstruction); an ischium; either one or two mid-caudal vertebrae (his paper contradicts itself on this); and a sequence of 12 articulated caudal vertebrae. Unfortunately, Jensen’s use of specimen numbers for most of these referred elements is inconsistent, but he is at least consistent in referring to the second scapulocoracoid as BYU 5501.

Supersaurus vivianae holotype scapulocoracoid BYU 9025, photographed at the North American Museum of Natural Life. The exhibit text reads: “Supersaurus scapula and coracoid. This is the actual Supersaurus bone that the world saw when the announcement was made of the new animal’s discovery in 1972. The scapula lay in the ground for five more years, waiting for the collection of other fossils that lay in the path of excavation. The flatness of the bone presented a challenge to “Dinosaur Jim” Jensen, who had to figure out a way to get the bone safely out of the ground. He finally accomplished this by cutting the scapula into three pieces. In 1988, Cliff Miles, Brian Versey and Clark Miles prepared the bone for study. It is still one of the largest dinosaur bones known in the world. Specimen on load from Brigham Young University’s Earth Science Museum. Late Jurassic/Early Cretaceous (about 144 million years ago)

2. Ultrasaurus macintoshi, based on the holotype BYU 9044 (BYU 5000 of his usage), a dorsal vertebra measuring 1.33 m in height. To this, he referred BYU 9462 (BYU 5001 of his usage), a scapulocoracoid measuring 2.7 m in length; BYU 9024 (BYU 5003 of his usage), a huge cervical vertebra; and an anterior caudal vertebra.

Ultrasaurus macintoshi holotype dorsal vertebra BYU 9044, photographed at the North American Museum of Natural Life. (It’s incredibly hard to photograph well because it’s behind reflective glass.)

3. Dystylosaurus edwini, based on the holotype BYU 4503 (BYU 5750 of his usage), a dorsal vertebra. He did not refer any other material to this taxon, and considered it “Family indeterminate” commenting that it “no doubt represents a new sauropod family”. Poor Dystylosaurus has always been the unloved member of this group, and pretty much ignored in the literature aside from the Curtice & Stadtman (2002) synonymisation paper discussed below.

Dystylosaurus edwini holotype BYU 4503, a diplodocoid anterior dorsal vertebra.

In a subsequent paper, Jensen (1987:600–602) removed the big cervical BYU 9024 (BYU 5003 of his usage) from Ultrasauros and reassigned it to Diplodocidae. The text of this paper never refers it to Supersaurus vivianae in particular, but it is illustrated and captioned as belonging to that taxon (Jensen 1987:figures 7A-B, 8C), and this assignment is generally assumed to have been meant.

When Jensen became aware of Kim’s (1983) preoccupation of the name Ultrasaurus, he recognised that his own genus needed a new name. At his suggestion, Olshevsky (1991) erected the replacement name Ultrasauros (with a single-letter spelling difference) for Jensen’s taxon based on the dorsal vertebra BYU 9044. We will use this revised spelling hereon, and the taxon Ultrasaurus Kim 1983 is of no further interest to this story.

The relevant extract from Olshevsky (1991:139).

4. Curtice’s synonymies

This was how things stood, with Jensen’s assignment of the material to his three new genera standing unchallenged, until Brian Curtice came on the scene in the mid 1990s. In a series of three publications (two papers, one abstract), he first synonymised Ultrasauros with Supersaurus, then Dystylosaurus also with Supersaurus, and finally (tentatively) Supersaurus itself with Barosarus. If Curtice’s suggestions were all correct, then there were no new sauropods from Jensen’s work in the the Dry Mesa quarry, just a lot of Barosaurus material.

Was he right? We’ll now consider each of the three publications in turn.

First, Ultrasauros. Jensen had always considered this genus to be a brachiosaurid due to the morphology of the scapulocoracoid BYU 9462 — and indeed this element does seem to be brachiosaurid. Unfortunately, he did not found the taxon on this element, but on the dorsal vertebra BYU 9044. Curtice et al. (1996) re-examined this element, and argued convincingly that it was not an anterior dorsal from a brachiosaurid, as Jensen had thought, but a posterior dorsal from a diplodocid. Since its neural spine morphology matches that of the first preserved sacral spine (S2) of the Supersaurus sacrum, and since it was found between the two Supersaurus scapulocoracoids, Curtice et al. (1996:94) considered BYU 9044 to be a vertebra of Supersaurus (belonging to the holotype individual), and therefore concluded that Ultrasauros was a junior subjective synonym of Supersaurus. They inferred that the referred Ultrasauros scapulocoracoid BYU 9462 therefore did not belong to the same species as the type, since it was brachiosaurid, and referred it to Brachiosaurus sp.

We consider all of Curtice et al.’s (1996) arguments well-founded and convincing, and agree with their conclusions. As a result, both spellings of Jensen’s brachiosaurid genus are now discarded: Ultrasaurus as a nomen dubium, and Ultrasauros as a junior synonym.

Curtice et al. (1996:figure 2). “Uncrushed” Supersaurus vivianae caudal dorsal, BYU 9044, right lateral view.

A few years later, Curtice and Stadtman (2002) took aim at Dystylosaurus. Jensen had argued that it was unique because of the paired centroprezygapophyseal laminae that supported each prezygapophysis from below — and it was from this feature than the genus took its name. But Curtice and Stadtman pointed out that this supposedly unique feature is in fact almost ubiquitous in diplodocids. Because it, too, was found between the two Supersaurus scapulae (close to the Ultrasaurus dorsal), Curtice and Stadtman referred it, too, to Supersaurus, thereby collapsing all three of Jensen’s taxa into one. This argument, too, is well supported and has been generally accepted.

Finally, in a sole-authored abstract, Curtice (2003) hedged about whether he considered Supersaurus to be Barosaurus. I will quote directly, as the line of reasoning is vague and difficult to summarise:

The question of is Supersaurus truly a distinct genus from Barosaurus is now testable. The former Dystylosaurus dorsal vertebra provides an autapomorphy for Supersaurus, that being a strongly reduced bifid neural spine on dorsal four. This loss of bifidity is important for in all other diplodocids the neural spine is still deeply bifurcated on dorsal four. Only Barosaurus has a reduction in cleft depth that far forward in the dorsal column. Supersaurus has all but lost the cleft, more closely resembling the sixth dorsal vertebra of Barosaurus than the fourth.

It is disappointing that this abstract never became a more rigorously argued paper, because the conclusion here is highly equivocal. Curtice appears to be saying that Supersaurus is distinct from Barosaurus — but only on the basis of bifidity reducing two vertebrae more anteriorly in Supersaurus. In other words, he seems to be suggesting that the two taxa are indisinguishable aside from this rather minor difference.

At any rate, this speculation in a conference abstract has generally been ignored, and Supersaurus considered a valid and distinct genus.

5. Jimbo the WDC Supersaurus

In 2008, Lovelace et al. (2008, duh) described WDC DMJ-021, a new specimen of Supersaurus vivianae at the Wyoming Dinosaur Center that is known informally as “Jimbo”. (Confusingly, they refer to the Supersaurus holotype scapulocoracoid by yet a third specimen number, BYU 12962; but we will continue to use BYU 9025 here. It is possible that BYU 12962 is the revised specimen number of the referred scapulocoracoid, not the holotype.)

Lovelace et al. (2008) did not justify in detail their referral of Jimbo to Supersaurus. The closest the come is this brief passage on page 529–530:

While a scapula is not known for WDC DMJ-021, other elements are identical to axial elements referred to the type individual of Supersaurus. Referral of all material is supported by relative position within their respective quarries (Curtice and Stadtman 2001; Lovelace 2006), size of the skeletal elements, and congruence of phylogenetically significant diplodocid characters between the scapula and referred material.

All of this is kind of weaselly. What it amounts to is this: vertebrae are “identical” to those referred to the BYU Supersaurus (but not really, as we’ll see), and the elements are really big, and the Supersaurus holoype scap comes out in about the same place as Jimbo in a phylogenetic analysis if you code them up separately. This is weak sauce, and I would really have liked to see a much more explicit “Jimbo shares synapomorphies X, Y and Z with BYU Supersaurus” section.

Among the ways in which the justification for this assignment disappoints is that the presacrals that are described as “identical” to the BYU elements are not at all well preserved (Lovelace et al. 2008:figures 3D–E, 4A, 5A): in particular C13, presumably the best preserved cervicals as it is the only one illustrated, is missing the condyle, prezygapophyses and neural spine. It’s not possible to be sure in light of the small monochrome illustrations in the paper, but it does not seem likely that these elements can be reliably assessed as identical to the BYU cervical.

Lovelace et al. (2008:figure 3). Lateral views of cervical vertebrae from A, Diplodocus carnegii (Hatcher 1901); B, Barosaurus lentus (Lull 1919); C, Apatosaurus louisae (Gilmore 1936); D and E, Supersaurus vivianae; demonstrating pneumatic modifications of centra. Supersaurus has the least amount of modification with minimal size for pneumatopores. Internal structure is similar to that seen in other diplodocids (Janensch, 1947). Left lateral view of Cv.13 (D, missing the condyle, prezygapophyses and neural spine; length of incomplete centra 94cm). E, cross section through Cv.11, 5cm posterior of the diapophysis.

The big surprise in the Jimbo paper is that in the phylogenetic analysis (Lovelace et al. 2008:figure 14), the compound BYU+WDC Supersaurus is recovered as an apatosaurine, the sister taxon to Apatosaurus, rather than as a diplodocine as had been assumed in previous studies due to its resemblance to the diplodocine Barosaurus.

The huge specimen-level phylogenetic analysis of diplodocoids by Tschopp et al. (2015) corroborated Lovelace et al’s (2008) referral of the WDC specimen to Supersaurus vivianae, as the two species were sister groups in all most parsimonious trees, with quite strong character support (Tschopp et al. 2015:187). But it placed the Supersaurus clade at the base of Diplodocinae, not within Apatosaurinae as Lovelace et al. (2008) had found.

This, then, was the state of play when Matt and I started to work on Supersaurus during the 2016 Sauropocalypse: Ultrasauros and Dystylosaurus had both been sunk into Supersaurus, and the WDC specimen had been referred to the same species.

Next time, we’ll look what Matt and I found in Utah, and what we think it means for Supersaurus and its friends.

 

References

  • Curtice, Brian D. 2003. Two genera down, one to go? The potential synonomy [sic] of Supersaurus with Barosaurus. Southwest Paleontological Symposium 2003, Guide to Presentations. Mesa Southwest Museum, January 25 2003. Unpaginated.
  • Curtice, Brian D. and Kenneth L. Stadtman. 2001. The demise of Dystylosaurus edwini and a revision of Supersaurus vivianae. Western Association of Vertebrate Paleontologists and Mesa Southwest Museum and Southwest Paleontologists Symposium, Bulletin 8:33-40.
  • Curtice, Brian D., Kenneth L. Stadtman and Linda J. Curtice. 1996. A reassessment of Ultrasauros macintoshi (Jensen, 1985). M. Morales (ed.), “The continental Jurassic”. Museum of Northern Arizona Bulletin 60:87–95.
  • George, Jean. 1973a. Supersaurus, the biggest brute ever. Denver Post, Empire Magazine. May 13, 1973.
  • George, Jean. 1973b. Supersaurus, the biggest brute ever. Reader’s Digest (June 1973):51–56.
  • Glut, Donald F. 1997. Dinosaurs: the Encyclopedia. McFarland & Company Inc., Jefferson. 1076 pp.
  • Jensen, James A. 1985. Three new sauropod dinosaurs from the Upper Jurassic of Colorado. Great Basin Naturalist 45(4):697–709.
  • Jensen, James A. 1987. New brachiosaur material from the Late Jurassic of Utah and Colorado. Great Basin Naturalist 47(4):592–608.
  • Kim, Hang-mook. 1983. Cretaceous dinosaurs from South Korea. Journal of the Geological Society of Korea 19(3):115–126.
  • Lovelace, David M., Scott A. Hartman and William R. Wahl. 2008. Morphology of a specimen of Supersaurus (Dinosauria, Sauropoda) from the Morrison Formation of Wyoming, and a re-evaluation of diplodocid phylogeny. Arquivos do Museu Nacional, Rio de Janeiro 65(4):527–544.
  • Olshevsky, George. A revision of the parainfraclass Archosauria Cope, 1869, excluding the advanced Crocodylia. Mesozoic Meanderings 2:1–196.
  • Tschopp, Emanuel, Octávio Mateus and Roger B. J. Benson. 2015. A specimen-level phylogenetic analysis and taxonomic revision of Diplodocidae (Dinosauria, Sauropoda). PeerJ 2:e857. doi:10.7717/peerj.857

 

In a word, amazingly. After 6 days (counting public galleries last Sunday), 4300 photos, 55 videos, dozens of pages of notes, and hundreds of measurements, we’re tired, happy, and buzzing with new observations and ideas.

We caught up with some old friends. Here Mike is showing an entirely normal and healthy level of excitement about meeting CM 584, a specimen of Camarasaurus from Sheep Creek, Wyoming. You may recognize this view of these dorsals from Figure 9 in our 2013 PeerJ paper.

We spent an inordinate amount of time in the public galleries, checking out the mounted skeletons of Apatosaurus and Diplodocus (and Gilmore’s baby Cam, and the two tyrannosaurs, and, and…).

I had planned a trip to the Carnegie primarily to have another look at the Haplocanthosaurus holotypes, CM 572 and CM 879. I was also happy for the chance to photograph and measure these vertebrae, CM 36034, which I think have never been formally described or referred to Haplocanthosaurus. As far as I know, other than a brief mention in McIntosh (1981) they have not been published on at all. I’m planning on changing that in the near future, as part of the larger Haplocanthosaurus project that now bestrides my career like a colossus.

The real colossus of the trip was CM 555, which we’ve already blogged about a couple of times. Just laying out all of the vertebrae and logging serial changes was hugely useful.

Incidentally, in previous posts and some upcoming videos, we’ve referred to this specimen as Brontosaurus excelsus, because McIntosh (1981) said that it might belong to Apatosaurus excelsus. I was so busy measuring and photographing stuff that it wasn’t until Friday that I realized that McIntosh made that call because CM 555 is from the same locality as CM 563, now UWGM 15556, which was long thought to be Apatosaurus excelsus but which is now (i.e., Tschopp et al. 2015) referred to Brontosaurus parvus. So CM 555 is almost certainly B. parvus, not B. excelsus, and in comparing the specimen to Gilmore’s (1936) plates of CM 563, Mike and I thought they were a very good match.

Finding the tray of CM 555 cervical ribs was a huge moment. It added a ton of work to our to-do lists. First we had to match the ribs to their vertebrae. Most of them had field numbers, but some didn’t. Quite a few were broken and needed to be repaired – that’s what I’m doing in the above photo. Then they all had to be measured and photographed.

It’s amazing how useful it was to be able to reassociate the vertebrae with their ribs. We only did the full reassembly for c6, in part because it was the most complete and perfect of all of the vertebrae, and in part because we simply ran out of time. As Mike observed in his recent post, it was stunning how the apatosaurine identity of the specimen snapped into focus as soon as we could see a whole cervical vertebra put back together with all of its bits.

We also measured and photographed the limb bones, including the bite marks on the radius (above, in two pieces) and ulna (below, one piece). Those will of course go into the description.

And there WILL BE a description. We measured and photographed every element, shot video of many of them, and took pages and pages of notes. Describing even an incomplete sauropod skeleton is a big job, so don’t expect that paper this year, but it will be along in due course. CM 555 may not be the most complete Brontosaurus skeleton in the world, but our ambition is to make it the best-documented.

In the meantime, we hopefully left things better documented than they had been. All of the separate bits of the CM 555 vertebrae – the centra, arches, and cervicals ribs – now have the cervical numbers written on in archival ink (with permission from collections manager Amy Henrici, of course), so the next person to look at them can match them up with less faffing about.

We have people to thank. We had lunch almost every day at Sushi Fuku at 120 Oakland Avenue, just a couple of blocks down Forbes Avenue from the museum. We got to know the manager, Jeremy Gest, and his staff, who were unfailingly friendly and helpful, and who kept us running on top-notch food. So we kept going back. If you find yourself in Pittsburgh, check ’em out. Make time for a sandwich at Primanti Bros., too.

We owe a huge thanks to Calder Dudgeon, who took us up to the skylight catwalk to get the dorsal-view photos of the mounted skeletons (see this post), and especially to Dan Pickering, who moved pallets in collections using the forklift, and moved the lift around the mounted skeletons on Tuesday. Despite about a million ad hoc requests, he never lost patience with us, and in fact he found lots of little ways to help us get our observations and data faster and with less hassle.

Our biggest thanks go to collections manager Amy Henrici, who made the whole week just run smoothly for us. Whatever we needed, she’d find. If we needed something moved, or if we needed to get someplace, she’d figure out how to do it. She was always interested, always cheerful, always helpful. I usually can’t sustain that level of positivity for a whole day, much less a week. So thank you, Amy, sincerely. You have a world-class collection. We’re glad it’s in such good hands.

What’s next? We’ll be posting about stuff we saw and learned in the Carnegie Museum for a long time, probably. And we have manuscripts to get cranking on, some of which were already gestating and just needed the Carnegie visit to push to completion. As always, watch this space.

References

Cool new paper out today by Yara Haridy and colleagues, describing the oldest known osteosarcoma in the vertebrate fossil record. The growth in question is on the proximal femur of the Triassic stem turtle Pappochelys.

Brian Engh did his usual amazing job illustrating this pervert turtle with no shell and a weird growth on its butt.

I don’t have a ton more to say about the paper, it’s short and sweet. I got to meet Yara in person at SVP last fall and learn about her research, and there is going to a LOT more weird stuff coming down the pike. She is after some really fundamental questions about where bone comes from, how it develops in the first place, and how it remodels and heals. Get ready to see some crazy jacked-up bones from other basal amniotes in the next few years, including some vertebrae that are so horked that Yara and I spent some time discussing which end was which.

On a probably inevitable and purely selfish personal note, I don’t blog nearly enough about turtles. I like turtles. Which, if you’re going to say, you gotta say like this kid:

In fact, I love turtles, and if there were no sauropods, I’d probably be working on turtles. Other people show you pictures of their cats, I’m going to show you pictures of my turtle, Easty. She’s a female three-toed box turtle, Terrapene carolina triunguis.

Here she is closing in on an unlucky roly-poly (or pill bug, if you prefer).

Having a close encounter with our cat Berkeley last summer. I think Easty kinda blew Berkeley’s mind. She’s been around our other cat, Moe, for years, so she’s completely unfazed by cats. But Berkeley is a SoCal kitty who showed up on our doorstep starving and yowling when he was about eight weeks old, so this was his first encounter with a turtle.

Berkeley batted at Easty’s shell a couple of times and then spent about half an hour having a visible existential crisis. Here was a small creature that he couldn’t frighten and couldn’t move, which was not the least bit afraid of him and either ignored him or treated him like an obstacle. Watching them interact — or rather, watching Easty act and Berkeley react — was solid entertainment for most of the afternoon.

Why have I hijacked this post to yap about my turtle? Primarily because up until now I’ve had a hard time visualizing a stem turtle. Turtles are so much their own thing, and I’ve been so interested in them for virtually my entire life, that imagining an animal that was only partly a turtle was very difficult for me. The thing I like most about Brian’s art of the tumorous Pappochelys is that it reads convincingly turtle-ish to me, especially the neck and head:

So congratulations to Yara and her coauthors for a nice writeup of a very cool find, and to Brian for another vibrant piece of paleoart. Triassic turtles sometimes had cancer on their butts. Tell the world!

Since I’ve already blown the weekly schedule here in the new year, maybe my SV-POW! resolution for 2019 will be to blog more about turtles. I’m gonna do it anyway, might as well make it a resolution so I can feel like I’m keeping up with something. Watch this space.

Reference

Here’s a frozen pig head being hemisected with a band saw.

The head in question, and the other bits we’ll get to later on in this post, both came from Jessie Atterholt’s Thanksgiving pig. As soon as Jessie knew she was cooking a pig for Thanksgiving, she had a plan for the head and the feet: cut ’em in half, skeletonize one half (like Mike did with his pig head), and plastinate the other. Jessie has her own plastination setup and you can see some of her work in her Instagram feed, here.

Here’s the freshly hemisected head. At one time or another, about four of us were involved in checking the alignment of the cut, with the intention of just missing the nasal septum (it can be easier to see some of the internal nasal anatomy if the septum’s all on one side). But we were all wrong–not only did the saw hit the nasal septum dead on, it hemisected the septum itself. Which I guess is the next-best possible outcome. The septum is the big expanse of white cartilage behind the nose and in front of the brain. You have one, too–it separates your left and right nasal cavities–but yours is a lot thinner.

Here’s the left half washed off and cleaned up a bit.

I was completely entranced by the little blood vessels inside the nasal septum, seen here as tiny traceries of red inside the blue-white cartilage. Also notice the frontal sinus above the septum and in front of the brain.

Here’s the right half in a postero-medial oblique view. Shown well here are the first two cervical vertebrae, plus part of the third, and the intervertebral joints. This was a young pig and the remains of growth plates are still visible between the different ossification centers of the vertebrae. If I get inspired (= if I get time) I might do a whole post on that.

It wasn’t my pig or my show, but Jessie made me a gift of two pig feet, and I got a little time on the saw. Here I’m using a plastic tool to push one of the pig’s hind feet through the saw.

We had been dithering over how best to prep the feet but the lure of the band saw proved irresistable: we hemisected all four. We’re planning to do half skeletonized/half plastinated preps for all of them, a forefoot and a hindfoot set for each of us.

Jessie and I were joined by two other WesternU anatomists, Thierra Nalley and Jeremiah Scott. Here Thierra is explaining to Jeremiah, who works on primate dentition and diet, that mammals have more parts than just teeth.

That’s a good segue to this video I shot, in which Thierra gives a quick tour of the hemisected pig head. All four of us have just come off of teaching human head and neck anatomy, so it was cool to see in another mammal the same structures we’ve just been dissecting in humans.

From 1:40 to 1:55 in the video Thierra and I are discussing the prenasal bone, something pigs have that we don’t. It’s the separate bone at the end of the snout in this mounted skeleton:

Darren discusses and illustrates the prenasal bone in this Tetrapod Zoology post.

Parting shots: many thanks to Ken Noriega and Tony Marino of WesternU’s College of Veterinary Medicine for their guidance, assistance, and expertise. Jessie covered this dissection as an Instagram story, here–I believe you have to be signed in to see it. Update: Jessie added a regular stream post, with lots of features labeled, here. I’ll probably have more to say about this pig and its bits in the future. Stay tuned!

For more hemisected heads and skulls, see:

I am still building up to a big post on vertebral orientation, but in the meantime, check out this caudal vertebra of a Komodo dragon, Varanus komodoensis. This is right lateral view–the vert is strongly procoelous, and the articular ends of the centrum are really tilted relative to the long axis. I find this encouraging, for two reasons. First, it helped me clarify my thinking on how we ought to orient vertebrae, which Mike wrote about here and here. And second, it gives me some hope, because if we can figure out why tilting your articular surfaces makes functional sense in extant critters like monitors, maybe we can apply those lessons to sauropods and other extinct animals.

This is LACM Herpetology specimen 121971. Many thanks again to Neftali Camacho for access and assistance, and to Jessie Atterholt for basically doing all the other jobs while I was faffing about with this Komodo dragon.