It’s a miracle!

June 30, 2019

I’ll see your face-of-the-blessed-virgin-in-a-waffle and raise you the fourth dorsal vertebra of the Giraffatitan brancai paralectotype BM.R.2181 (formerly HMN S II) in a dandelion leaf:

I saw this lying on the ground as my friend Nataley was playing a short set at a festival, and it immediately made me think of this:

Janensch (1950:Abb. 54). 17ter Präsakralwirbel (SII), Hinteransicht.

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Last time, I noted that photographs of the exact same object, even under the same lighting conditions, can come out different colours. That is one of the two reasons why I am not persuaded that the very different colours of my photos of the two Supersaurus scapulae is strong evidence that they are from different individuals.

The other reason is that, as BJ Nicholls pointed out in a comment on that post, “Color in fossils can be misleading even in real life. As bones erode out, surface float pieces can be bleached on exposed surfaces. Bones within a bed can vary a lot in color too.”

Here’s an example:

What we have here are some of bones from the skeleton of Charlie the monitor lizard. After I extracted these bones from Charlie’s decomposing carcass ten years ago (can it really have been that long?!) I have left them sitting on a tray, awaiting articulation.

At the top of this photo is a scapulocoracoid; at the bottom, some dorsal vertebrae. As you can see, the former has bleached white, while the latter have remained ivory coloured. Remember, these are bones from the same individual that were extracted at the same time (give or take maybe a day or two), and that have been in exactly the same situation (on a tray, on a window sill, in my office) ever since.

The moral: bone colour doesn’t really tell you much at all.

In part 5 of the Supersaurus series, I made the point that my photos of Scap A and Scap B seem to show them as being very different colours, suggesting different preservation. However …

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.

The first of these points has just been brought home to me by an unrelated experience. The rendering on an outside wall of our house had come loose, and needed to be removed and replaced. I am soliciting a quote for doing the re-rendering, and took some photos to send to the builder who might be doing the work. First, the whole of the relevant wall:

And now a close-up of the leftmost part, around shoulder level:

Now these photos were taken with the same pretty good camera (Google Pixel 4a), in the same place, under the same lighting conditions, eleven seconds apart. Yet in the first photo, the underlying brickwork is brown, and in the second it’s grey — presumably because the camera made a judgement about white balance based on what was in its viewfinder at the moment each photo was taken.

Here is the same part of the wall, juxtaposed, from both photos:

Let this be a cautionary tale: don’t over-interpret colour from photos. When comparing the colour of two fossils, the best thing to do is put them physically next to each other so you can see both at once under identical conditions. (Sadly, that wasn’t an option with the two Supersaurus scapulocoracoids.)

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.

More compellingly, Andrea Cau re-ran Tschopp et al.’s (2015) analysis with Supersaurus and Barosaurus constrained to be sister groups (thanks, Andrea!) and found that the best resulting trees were 18 steps longer than the unenforced trees (1994 steps vs 1976). This is convincing evidence that the totality of the Supersaurus material is not Barosaurus.

Is BYU Supersaurus a chimaera?

All of this strongly suggests — it comes close to conclusively proving — 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 (2001) 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 (2001) 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. 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.
  • 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

 

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. We’re not sure where Scap A is, but there is a good cast 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:

Cast of 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 cast 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 images 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 2001, 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 2001

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 2001) 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 (2001:39) 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 (2001) 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 (2001) 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 (2001:39) 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 (2001) 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. 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.
  • George, Jean. 1973c. 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.

 

You may recall that sculptor James Herrmann did a life-size bronze of Aquilops (shown above) back in 2017. I love it, and I’d get one in a heartbeat if I had the disposable income or the space in which to display it. Since I have neither, I got in touch with James and asked if he’d be interested in doing a casting of just the bust. Happily for me, he was game, and today this sturdy wooden crate arrived in the mail:

Inside, insanely well-packed in lots of cushy foam:

That’s a t-shirt James threw in with my order. But you’re probably more interested in this, which was also in the crate:

Unpacked and plunked on the crate lid on the lawn since it was the best I could come up with on short notice:

Some nicer photos by James of the same sculpture in prettier surroundings:

The bust is mounted on a gorgeous piece of polished green marble, with thick felt on the bottom so it won’t scratch up the furniture. The max length of the base is 9.5 inches and when standing on a desk or table, the whole piece is almost exactly 12 inches tall. I haven’t weighed it but it’s heavy enough that you could knock someone out with it, no problem.

I’d say it looks nice, but that’s both redundant, in this photo-heavy post, and a gross understatement. It looks absurdly nice, like it wandered into my space from some other, classier joint. I have some serious desk-cleaning to do so it won’t look like I stole this.

Instead of doing a big run of these, James is having them cast one at a time, on demand. The cost is $500 plus shipping; mine came to $573.33 shipped. If you want one, or want to browse James’s catalogue, or commission something yourself, you can find him at http://www.herrmannstudio.com/.

Thanks, James, for your interest in ‘my’ critter, for your skill in bringing it to life, and for making this bust available. I love it.

Here’s a bit of light relief, in the middle of all those looong posts about Supersaurus and its buddies. When Matt and I were at NAMAL on the last day of the 2016 Sauropocalypse, we took a bunch of tourist shots. Two of them were of a skull and first three cervical vertebrae from what I take to be Diplodocus or something close, and happened to be from sufficiently close angles that they make a pretty good anaglyph. Here it is!

(If you don’t have the 3D glasses that you need to see this, get some. Seriously, how many times do I have to tell you?)

If anyone out there is familiar with NAMAL (on indeed with diplodocid skulls) and can confirm or contradict my identification, I’d appreciate it. Best of all would be a photo of the signage associated with this specimen, such as I should have taken.

By the way, if you’re not used to the ways of sauropods, you might be thinking “Mike, you dummy, there are only two vertebrae there”. But in saropods, the atlas (1st cervical) is a tiny, inconsequential element that frequently fuses to the axis (2nd cervical). So what looks like the first cervical here is really 1+2. If you look closely, you can see the blades of the atlas projecting backwards and upwards, across the surface of the axis.