Back in 2005, three years before their paper on the WDC Supersaurus known as Jimbo was published, Lovelace at al. presented their work as a poster at the annual SVP meeting. The abstract for that poster appeared, as usual, in the abstracts book that came as a supplement to JVP 25 issue 3. But the poster itself was never published — which is a shame, as it contains some useful images that didn’t make it into the descriptive paper (Lovelace et al. 2008).

With Dave and Scott’s blessing, here it is! Click through for full resolution, of course.

And here’s the abstract as it appeared in print (Lovelace et al. 2005):

REVISED OSTEOLOGY OF SUPERSAURUS VIVIANAE

LOVELACE, David, HARTMAN, Scott, WAHL, William, Wyoming Dinosaur Center, Thermopolis, WY

A second, and more complete, associated specimen of Supersaurus vivianae (WDC-DMJ021) was discovered in the Morrison Formation of east-central Wyoming in a single sauropod locality. The skeleton provides a more complete picture of the osteology of S. vivianae, including a surprising number of apatosaurine characteristics. The caudals have heart shaped centra that lack a ventral longitudinal hollow, and the rectangular distal neural spines of the anterior caudals are mediolaterally expanded similar to Apatosaurus excelsus. The centra of the anterior caudals are procoelous as in other diplodocids, but the posterior ball is very weakly pronounced. The robusticity of the tibiae and fibulae are intermediate between Apatosaurus and diplodocines. The cervical vertebrae demonstrate classic diplodocine elongation with an elongation index ranging from 4 to 7.5. All 7 of the new cervicals have a centrum length that exceeds 1 meter. Mid-posterior cervicals are semicamellate at mid-centra near the pneumatic foramina. The dorsal vertebrae exhibit a high degree of elaboration on laminae, and extremely rugose pre and postspinal laminae. Costal elements are robust, with complex pneumatic innervations in the rib head. Although unknown in other diplodocids, early reports described pneumatic ribs in an A. excelsus; unfortunately the described specimen is unavailable.

Inclusion of lesser-known North American diplodocids such as Supersaurus, Seismosaurus and Suuwassea in phyolgenetic studies, may provide a framework for better understanding North American diplodocid evolution.

Many thanks to Dave and Scott for permission to share this important poster more widely. (Publish your posters, people! That option didn’t exist in 2005, but it does now!)

References

  • Lovelace, David M., Scott A. Hartman and William R. Wahl. 2005. Revised Osteology of Supersaurus vivanae (SVP poster). Journal of Vertebrate Paleontology 25(3):84A–85A.
  • 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.
Advertisements

I keep wishing there was a single place out there where I could look up Jensen’s old BYU specimen numbers for Supersaurus, Ultrasaurus and Dystylosaurus elements, and find the modern equivalents, or vice versa. Then I realised there’s no reason not to just make one. So here goes! The first column shows the specimen numbers as used in Jensen (1985), and last column contains Jensen’s own assignments except where noted.


Jensen Element New Notes
5000 posterior dorsal vertebra 9044 holotype of Ultrasauros
5001 scapulocoracoid 9462 referred to Ultrasauros
5002 anterior caudal vertebra 9045 referred initially to Ultrasauros, then Supersaurus [1]
5003 mid-cervical vertebra 9024 referred initially to Ultrasauros, then Supersaurus [2]
5500 left scapulocoracoid [3] 9025 holotype of Supersaurus
5501 right scapulocoracoid [3] 12962 referred to Supersaurus, although found first
5502 sequence of 12 caudals [4] 9084 referred to Supersaurus
5503 right ischium [4] 12946 referred to Supersaurus
5504 two mid-caudal vertebrae [4] ?9077[5] referred to Supersaurus
5750 anterior dorsal vertebra 4503 holotype of Dystylosaurus

By the way, does anyone know why the numbers were changed?

 

Notes

[1] This diplodocid caudal, which is obviously diplodocid based on Jensen’s own illustrations (Jensen 1985:figures 2D,E, 3E), was reassigned to Supersaurus by Curtice (1995).

[2] Jensen (1987:602-603) recognised his own error in referring this cervical to the brachiosaurid taxon Ultrasaurus, based on its bifurcated neural spine. He “provisionally refer[red] it to the Diplodocidae” in the text, but without specifying a genus or species. However in caption to illustrations in the same paper (Jensen 1987:figures 7A, B, 8C) he names the element as Supersaurus vivianae without comment.

[3] Jensen’s (1985) original description describes BYU 5500 (=BYU 9025) as a right scapulocoracoid, implying that BYU 5501 is the left; but this is incorrect.

[4] Jensen’s original Supersaurus/Ultrasaurus/Dystylosaurus description is confusing and contradictory in his assignment of specimen numbers. In his systematic palaeontology section, Jensen (1985:701) says that BYU 5502 is the ischium, BYU 5503 is the pair of mid-caudals and BYU 5504 is the sequence of 12 caudals. But the description on the same page contradicts this, giving the assignments shown here. The casting vote goes to the caption of Jensen (1985:figure 7), in which part A illustrates BYU 5503, the ischium; and parts C, D and D1 illustrate caudals that do not appear to be part of sequence of twelve.

[5] Curtice et al. (2001:36) say “An additional caudal vertebra (BYU 9077) is referred to (and figured as) Supersaurus in the text of Jensen (1985)”. This probably refers to Jensen 1985:figure 7:C, D, D1, which are captioned as follows: “C, BYU 5033, Supersaurus vivianae, referred specimen, ischium [sic]. D, D1, BYU 5504, Supersaurus vivianae, referred specimen, caudal vertebra.” Since part C of the figure is clearly a caudal vertebra, and since BYU 5503 is also illustrated as an ischium in part A of the same figure(!), it seems most likely that the caudals in part C and parts D and D1 of this figure are the pair described as BYU 5044 on pages 701-704.

 

Commentary (i.e. pointless whining)

For all his innovations in skeletal mounting and his amazing discoveries in the field, Jensen was evidently a markedly careless palaeontologist in many respects, and his contempt for specimen numbers in particular has created enormous problems. Even within a single page — even within a single figure caption — he was capable of contradicting himself on the numbers assigned to specimens. Most illustrations don’t give specimen numbers at all. And while in many respects the later work of Curtice et al. (1996) and Curtice and Stadtman (2001) is much better, they did the world no favours by simply switching to the new specimen numbers without providing a definitive key like the one I am trying to build here. It’s pretty silly that, 23 years on, we are reduced to guesswork like note 5.

 

References

  • Curtice, Brian D. 1995. A description of the anterior caudal vertebrae of Supersaurus vivianae. Journal of Vertebrate Paleontology 15(3):25A.
  • 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.
  • 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.

I got a wonderful surprise a couple of nights ago!

Supersaurus referred scapulocoracoid BYU 12962 back when it was still in the ground. Rough composite assembled from screenshots of the video below, from about 23m17s.

I found myself wondering where the widely quoted (and ludicrous) mass estimate of 180 tons for Ultrasauros came from, and went googling for it. That took me to a blog-post by Brian Switek, which linked to a Google Books scan of what turned out to be my own chapter on the history of sauropod research (Taylor 2010) in the Geological Society’s volume Dinosaurs and Other Extinct Saurians: a Historical Perspective. So it turns out that I once knew the answer to that question. My chapter references McGowan (1991:118), which says:

Jim Jensen’s (1985) Ultrasaurus (“beyond lizard”), found in Colorado in 1979, had an estimated length of more than ninety-eight feet (30 m), compared with seventy-four feet (22.5 m) for the Berlin specimen of Brachiosaurus. This is a length increase of 1.32, so the weight increase would be (1.32)^3 = 2.3, giving an estimated weight of almost 180 tons.

[As I noted in my 2010 chapter, that’s based on Colbert’s (1962) equally silly estimate of 78 tonnes for MB.R.2181 (formerly HMN S II), the Girafatitan brancai paralectotype.]

So that’s a funny story and a mystery solved, but where it gets really good is that as I was grubbing around in the search results that led me to that conclusion, I stumbled on Episode 21 of the I Know Dino podcast, which contains a glorious embedded video: The Great Dinosaur Discovery, a 1976 film by BYU about Jensen’s work at quarries including Dry Mesa, and heavily featuring bones of what would become Supersaurus!

It’s very well worth 25 minutes of your time, despite the horrible 1970s documentary music, and brings actual new information to the table.

Some of the highlights include:

— Right from the start, seeing Jensen himself: someone I’ve been sort of familiar with from the literature, but never really imagined as being an actual human being.

— From about two minutes in, Jensen seems be uncovering bones in dry sand, rather like kids in a palaeo pits at some museums. It takes about one minute to uncover a nice tibia. Is it ever really that easy? Is the Dry Mesa quarry that easy to work?

— Putting faces to the important names of Vivian and Eddie Jones, the uranium prospectors who first led Jensen to several of his important sites, and after whom the species Supersaurus vivianae and Dystylosaurus edwini were named.

Vivian “Supersaurus” Jones and Eddie “Dystylosaurus” Jones in the field [from about 4m41s in the video]

— From about 13m30s onwards, we see what I think must be the Supersaurus pelvis that’s now on display at the North American Museum of Ancient Life. (It doesn’t actually look all that big, in the scheme of things.)

— From 16m50s onwards, things start to get real, with the uncovering (real or re-enacted) of the first Supersaurus scapulocoracoid: that is, the one that Jensen referred to in his 1985 paper as “first specimen”, but which in the end he did not designate as the holtotype. This bone, once accessioned, became BYU 12962 (but Jensen refers to it in his papers as BYU 5501).

The first appearance in the film of the Supersaurus scap BYU 12962 fully unconvered [18m11s]. You can easily recognise it as the bone that Jensen posed with from the lobe-shaped acromion process.

— Within seconds of our seeing the scap, Jensen decides the best thing to do is illustrate how it’s “like a sidewalk” by walking up and down on it. Seriously.

Oh, Jim.

— At about 19m30s, we see what is probably the big Barosaurus vertebra BYU 9024 whose identity Jensen changed his mind about a couple of times. Unfortunately, the film quality is very poor here, and you can’t make much out.

— From 20 minutes in, the video shows comparative skeletal reconstructions of Brontosaurus (clearly from Marsh 1891), “Brachiosaurus” [i.e. Giraffatitan] (clearly from Janensch 1950) and Supersaurus. The fascinating thing is that the latter is restored as a brachiosaurid — in fact, as a scaled-up Janensch-1950 Giraffatitan with some tweaks only to the head and anterior neck. So it seems Jensen thought at this time that he’d found a giant brachiosaur, not a diplodocid. (Note that this film was made three years before the Ultrasaurus scapulocoracoid was discovered in 1979, so the presumed brachiosaurid identity cannot have rested in that.)

Brontosaurus (yellow), Brachiosaurus (blue), and Supersaurus (white) — which is restored as a brachiosaurid.

— During this section, a fascinating section of narration says “The animal found here is so much larger than anything ever dreamed of, the press, for lack of scientific name, called it a Supersaurus.” If this is legit, then it seems Jensen is not guilty of coining this dumb name. It’s the first I’ve heard of it: I wonder if anyone can corroborate?

— As 22m06s we are told: “It was an AP newsman who broke the story to the world. Time and Life followed. Reader’s Digest ran the story. And National Geographic, one of the quarry sponsors, began an article.” I would love to get hold of the AP, Time, Life and National Geographic articles. Can anyone help? It seems that all these organisations have archives online, but they all suffer from problems:

Here’s that scap again, in the process of being excavated. [22:05]

— As 22m40s, Jack McIntosh turns up to give an expert opinion. I don’t know how much film of him there is out there, but it’s nice that we have something here.

Everyone’s favourite avocational sauropod specialist, Jack McIntosh.

— At 23:17, we get our best look at the scap, with a long, slow pan that shows the whole thing. (That’s the sequence that I made the composite from, that we started this whole post with.)

All in all, it’s a facinating insight into a time when the Dry Mesa quarry was new and exciting, when it was thought to contain only a single giant sauropod, when that animal was known only informally as “Supersaurus” having been so nicknamed by the media, and when it was (it seems) thought to be brachiosaurid. Take 25 minutes, treat yourself, and watch it.

Update (the next day)

The Wikipedia entry on Jim Jensen says that “In 1973, Brigham Young University cooperated with producer Steve Linton and director John Linton in order to produce The Great Dinosaur Discovery, a 1-hour-long color documentary showing Jensen’s on-site finds in Dry Mesa. […] the full-length documentary was reduced to a 24-minute-long mini-film which started airing on American television channels throughout the USA as of 1976.”

Can anyone confirm that the original date was 1973, and not 1976 as given on the short version that’s linked above?

And, more important, does anyone have access to the full-hour version?

 

References

 

My friend and frequent collaborator Jessie Atterholt has her office in the next building over from mine. When you walk in, you see something that looks approximately like this. Not exactly like this, because I took these photos in February and she’s changed a few things (and I’m rubbish about getting stuff posted in a timely fashion).

The last time I showed an office full of amazing stuff like this, it was Peter Dodson’s. It will come as no surprise that Jessie was Peter’s student at UPenn before she went to Berkeley for her PhD.

The far case holds mostly books and skulls. Dr. A has her own plastination setup for making preserved organs and organisms, and the snake on the second shelf here is one that she prepped herself. One side of the snake still has the skin on, the other half has been skinned to show the muscles. This is crunch week for me so I don’t have time to ID all of the stuff, but alert readers should have no problem spotting some digitally-resurrected Haplocanthosaurus bits.

Mostly skulls on the middle rack. The sirenian skull on the second shelf and the cave bear on the fourth are both casts, but almost everything else is real bone. The bighorn sheep on the middle shelf is a natural mummy.

Here’s a close-up of the top shelf. Other than some 3D-printed human skull bones sitting in front of the brain slice on the left, everything here is real bone, including the lion, baboon, and human skulls, and the giraffe cervicals winding across the top. Jessie’s been collecting since she was a kid and the African megafauna are gifts from a globe-trotting family friend.

The upper shelves here have quite a few of Jessie’s plastinated specimens, both whole organisms and things like hearts and kidneys from various critters.

A close-up of some of Jessie’s coolest anatomical preparations. In back is an internal cast of the lungs and bronchial tree of a cat. The baby rattlesnake died after eating a proportionally gigantic lizard — I was dumb and forgot to flip the snake over to show the lizard inside, plastinated along with its predator. The ground squirrel on the right is another half-fleshed, half-skinned plastinate, and the mouse up front is a classic dissection presentation, preserved forever through plastination.

I’ve heard it said that the difference between a collector and a hoarder is curation. As someone who definitely lurks more on the hoarder end of that spectrum (to paraphrase Dave Barry, if you could see my office you’d be blinded or driven insane), I’m pretty darned jealous of both the breadth of Jessie’s collection, and the skill and taste with which it is displayed. She’s featured some of these specimens on her Instagram, which I strongly recommend.

One of the strange things about Jensen’s 1985 paper is that the abstract implies that he informally considered the Ultrasauros scapulocoracoid to be the type specimen.

Cast of BYU 9462, scapulocoracoid referred to Ultrasaurus macintoshi (possibly intended to the be the holotype), at Brigham Young Museum. This photo is one of a series in which I turned the cast in place to obtain photos for a photogrammetric model.

Here’s what Jensen (1985:697) says:

From 1972 to 1982 three exceptionally large sauropod scapulocoracoids […] were collected from the base of the Brushy Basin Member of the Upper Jurassic, Morrison Formation, in western Colorado. Two of the scapulae are conspecific, but the third represents a second genus and possibly a new family. The two conspecific specimens are described here as Supersaurus vivianae; the second genus is described as Ultrasaurus mcintoshi.

But on page 704, he formally and unambiguously nominated the dorsal vertebra as the holotype:

Family Brachiosauridae
Ultrasaurus macintoshi, n. gen., n. sp.
[…]
Holotype.—BYU 5000, posterior dorsal vertebra.
Referred material.—BYU 5001, scapulocoracoid.

Stranger still, two years after this, Jensen (1987:603) straight up claimed – quite incorectly — that the scap was the Ultrasaurus holotype:

In 1979 a scapulocoracoid, 2.70 m (8’10”) long (Figs. 6A-B, 9I) was collected in the Dry Mesa Quarry. This scapula, BYU 5000 [sic; he meant BYU 5001], is readily referrable to the Brachiosauridae (Fig. 9H) and is the holotype of Ultrasaurus macintoshi Jensen, 1985.

But it sayin’ it’s so don’t make it so. The joint evidence of the 1985 abstract and the 1987 extract suggest that Jensen probably intended the scap to be the holotype and somehow accidentally designated the wrong element — or was persuaded to do so against his own judgement. But however it came about, the scap is not the holotype.

BYU 9462, the scapulocoracoid referred by Jensen to Ultrasauros. Mike Taylor for scale, doing a Jensen. Note that the actual specimen is very much a mosaic of bone fragments, rather than the solid, complete bone that the cast might suggest.

Instead, the holotype remains the large posterior dorsal vertebra BYU 9044 (BYU 5000 of Jensen’s usage) which Curtice et al. (1996) convincingly showed to be diplodocid, and referred to Supersaurus, making Ultrasaurus (and its subsequent replacement Ultrasauros) a junior synonym of that name.

Ultrasauros macintoshi holotype dorsal vertebra BYU 9044, in left lateral view, photographed at the North American Museum of Natural Life. Sorry about all the reflections off the glass case.

But wait, wait. We’ve shown that there are probably two big diplodocids in the Dry Mesa quarry: Barosaurus (represented by the big cervical BYU 9024) and something different (represented by the “Dystylosaurus” dorsal, BYU 4503). The Ultrasauros holotype vertebra probably belongs to one of these (unless there are three big diplodocids in there but we’ll ignore that possibility). But we can’t tell whether the Ultrasauros dorsal belongs with the Barosaurus cervical or the Dystylosaurus dorsal.

All of this means that Ultrasauros is a synonym, but we don’t know of what. It might be Barosaurus; it might be Supersaurus, whatever that is, if it’s not a nomen dubium; and it might be Dystylosaurus, if Supersaurus is a nomen dubium. Yikes.

Well, then. Is it Barosaurus? Here are the dorsal vertebrae of the fairly complete AMNH specimen, in a composite that I put together a few years ago from McIntosh’s (2005) illustrations:

Barosaurus lentus AMNH 6341 dorsal vertebrae 1 to 9 in anterior, left lateral and posterior views. Modified from McIntosh (2005:figure 2.5)

We can compare these with the photo above of the Ultrasauros dorsal in left lateral view, and with this one in posterior view:

Ultrasauros macintoshi holotype dorsal vertebra BYU 9044, in posterior view, photographed at the North American Museum of Natural Life. Sorry about all the reflections off the glass case.

I wouldn’t want to hang too much on those poor quality, postage-stamp-sized monochrome photos of the Barosaurus dorsals. And I’m also more than aware of the imperfections in my photos of the “Ultrasauros” dorsal. But to the naked eye, there’s nothing here that immediately screams they couldn’t be the same thing.

Lull’s (1919) monograph on the original Barosaurus specimen YPM 429 also illustrated a posterior dorsal, which he designated D9. Lull helpfully provided both drawings and photographs:

Lull (1919: plate IV: parts 4-6). Barosaurus lentus holoype YPM 429, 9th dorsal vertebra in anterior, right lateral and posterior views (line drawing).

Lull (1919: plate IV: parts 4-6). Barosaurus lentus holoype YPM 429, 9th dorsal vertebra in anterior, right lateral and posterior views (photographs).

With something a bit more substantial to go on, the case for the Ultrasaurus vertebra being Barosarus doesn’t look so good.

Most obviously, its centrum is much longer than that of the Barosaurus dorsal — and indeed, than any posterior dorsal vertebra of any diplodocid. This character is the reason — the only reason — that Jensen (1985:704) initially thought it was brachiosaurid: “Ultrasaurus shares the family characteristic of a long dorsal centrum with Brachiosaurus, but in other features it has no parallel with that genus”. Curtice et al. (1996:90) argued that “extensive transverse and oblique crushing artificially elongate the centrum […]. Without the crushing […] the centrum shrinks considerably in length”. Based on my photos, I can’t really see any justification for this claim, but Curtice spent waaay more time with this specimen than I have done, so I’m going to hold that observation lightly.

But there are other features of BYU 9044 that are not a good match for Lull’s illustrations. These include a less robust looking and more prominently laminated subzygapophyseal neural arch, and a neural spine that is anteroposteriorly broader but transversely narrower than in Lull’s specimen. Also, the apex of the neural spine in anterior or posterior view is convex in BYU 9044 but concave in YPM 429.

None of these characters can be considered to definitely separate BYU 9044 from Barosaurus, especially in light of that element’s crushing, the imperfect preservation of Lull’s specimen, the possibility of serial variation, and the fact that I am working only from photographs and drawings of both. But when you put all the differences together, they combine to at least suggest that Ultrasaurus is not Barosaurus — and that it is therefore most likely Supersaurus/Dystylosaurus.

So what about the scapulocoracoid?

It looks brachiosaurid, as Jensen observed. Curtice et al. (1996) concurred, and referred it to Brachiosaurus sp. In fact, when compared with the best-preserved scapula of a known brachiosaurid Giraffatitan HMN Sa 9), it’s not all that similar:

Brachiosaurid scapulocoracoids. Left: cast of BYU 9462, right scapulocoracoid referred to Ultrasauros macintoshi, at Brigham Young Museum, with Mike Taylor for scale. Right: HMN Sa 9, left scapula only (coracoid is not co-ossified) of Giraffatitan brancai, scaled to same blade length as BYU 9462, photo by FunkMonk (Michael B. H.), CC By-SA.

It’s apparent, when looking at the two scaps together, that there are significant differences: BYU 9462 is in every respect less robust, having a less expanded distal blade, a more constricted midshaft, a less promiment and narrower acromial ridge and a much less robust ventral ridge. In addition, the acromion process is hooked in Sa 9, so that its tip projects laterally, whereas it is rounded in BYU 9462. Finally, the shapes of the distal blades differ, having a gently rounded profile in BYU 9462 but a distinct kink in Sa 9 where the dorsal part of the margin inclines anterodorsally.

What does all this mean? We don’t know. I’m certainly not arguing that BYU 9462 is not brachiosaurid, as it does seem to differ less from Giraffatitan scapulae than from those of other sauropods. All I’m saying is that it’s not all that Giraffatitan-like. But then every bone that we know from both Giraffatitan and Brachiosaurus is significantly different between them (Taylor 2009:798), so if a subsequently discovered associated skeleton one day shows us that this is just what the scapulocoracoid of Brachiosaurus altithorax looks like, it would not be a huge shock.

Still, as things stand, I’m not really convinced that the referral to Brachiosaurus sp. — based on a not-particularly-close resemblance to a completely different brachiosaurid — is rock solid. Had the scap been the type specimen, as Jensen probably intended, I would consider that the sound move would be to continue to consider Ultrasauros as a distinct taxon from Brachiosaurus, unless and until an associated specimen demonstrates that synonymy is warranted.

But that’s all in Shoulda-Coulda-Woulda territory. In fact the scapulocoracoid is not the type specimen, and so the name Ultrasauros remains sunk, even though we can’t tell whether it’s a synonym of Barosaurus, Supersaurus or Dystylosaurus. That will remain the case unless someone takes the initiative to raise a new name for the scapulocoracoid — which we can, at least, be confident does not belong the diplodocid Ultrasauros. I think that would be a reasonable move for someone to make, but it’s not one that I feel moved to make myself.

… and with that, I think we have finally reached the end of this series. We may revisit it in the future to say more about Jimbo, or maybe Dinheirosaurus, but this series has been the substance of what we have to say. Hope you’ve enjoyed it!

References

 

 

Poor Dystylosaurus. Always the bridesmaid. No-one seems to care much about it, yet the one and only vertebra that bears that name is the single most diagnostic elements out of all the individual bones that have been assigned to Supersaurus over the years.

A nice drawing of the “Dystylosaurus” dorsal vertebra in anterior and right lateral views. It’s probably Tracey Ford’s work (awaiting confirmation), from the PaleoFile page on Supersaurus.

Unfortunately, we weren’t able to learn a whole ton about this vertebra on the Sauropocalypse visit. We did see it, but it was flat on its back on a shelf not much taller than the anteroposterior length of the bone itself, so we weren’t able to get a good look at it in anything but dorsal and ventral views. If we’d had more time to get things arranged, I’m sure the BYU people would have been happy to get it down from the shelf for us, but we simply had so much to do in their collections that time was never made for it.

BYU 4503, the holotype and only element of Dystylosaurus edwini, an anterior dorsal vertebra. here seen in approximately dorsal view with anterior to the top. Matt Wedel for scale.

Matt actually got some rather better photos a few years ago, though (based on his comment on that post), there are probably no more than the couple in that old blog-post. (By the way, notice how very different the colour of the bone appears in Matt’s old photos from how it appears in my more recent one above.)

Why do I say so confidently that the Dystylosaurus vertebra is diagnosable? Because it has a whole suite of characters that tell us it’s an anterior dorsal vertebra from a diplodocid (dual centroprezygapophyseal laminae, anteroposteriorly compressed spine composed primarily of spinozygapophyseal rather than spinodiapophyseal laminae, drooping transverse processes), yet two features of the spine are never seen in such vertebrae: the spine is wholly unsplit without even a hint of bifurcation, even featuring macronarian-like lateral apices; and it’s hollow inside rather than being constructed from intersecting plates of bone. (You can see the internal hollow in the photo above.)

So what happens to its genus name given the doubts about Supersaurus‘s diagnosability? The general trend of comments on these posts has been that Supersaurus should stand or fall on its holotype, and I am inclined to agree that parachuting in the Dystylosaurus vertebra or Jimbo as a neotype to save the name would be a mistake. For one thing, despite its numerous appearances in kids’ books, the name Supersaurus is not that important in the technical literature: for example, no-one has named a clade Supersaurinae or similar. For another, the holotypic scapulocoracoid BYU 9025 is only questionably undiagnosable. There would always be the possibility that if someone nominated a neotype and wrestled it through the ICZN petition process, someone else would find a good solid way to diagnose the original holotype. That would be embarrassing.

The rare ventral-ish view of the Dystylosaurus dorsal vertebra BYU 4503. Sorry it’s not better. I do have 93 photos of it in this shelf, all of them individually pretty terrible, which I took in the forlorn hope that one day we’ll get photogrammetry software simple enough and clever enough to make some kind of model out of them.

So I think we need to simply accept that the name Dystylosaurus, while perfectly diagnosable based on its holotype and only specimen, is destined to remain a junior synonym for as long as Supersaurus is considered taxonomically valid.

But it does leave Dystylosaurus in a bit of a quantum superposition. When Supersaurus is considered diagnosable, it ceases to exist, like a cat in a box. When Supersaurus is considered undiagnosable, it pops back into existence, like … well, a cat in a box. It’s an unsatisfactory kind of existence, but I think that’s the way it has to be.

So Dystylosaurus has its day — and it ends up being disappointing. Despite being perfectly diagnosable, it’s dependent for its validity on our assessment of other taxa. Some fossils just can’t catch a break.

This is a Galeamopus, roughly two feet long, sculpted by James Herrmann (who also made the life-size Aquilops sculpture and bust) for the Cincinnati Museum Center.

Here’s what it looks like on the other side.

From behind.

And from the front.

I dig this. I’m sure someone else must have done this half-skeletal reconstruction, half-fleshed life restoration style of sculpture before, but I can’t think of any museum-quality examples. The bronze is a nice touch.

Here’s a convincingly chunky Allosaurus.

About the sculpting process, James wrote (in an email with permission to cite):

I worked on all of the museum pieces with Glenn Storrs, Ph.D., vertebrate paleontologist with the Cincinnati Museum Center. He would tell me what he envisioned and provide me with reference material, I would sculpt it, take the clay to Glenn for his critique, take it back and make revisions. We went through several cycles of this for each piece and when I received the final approval I took each piece to the foundry.

Tyrannosaurs are to museums what roller-coasters are to amusement parks. Here’s Daspletosaurus.

My favorite thing about these sculptures is why they’re done in bronze. It’s not just for posterity. James again:

The idea was to provide a small sculpture of each skeletal reconstruction on display for people to touch and feel. It was felt that this element of touch would be particularly important to accommodate the needs of the visually impaired museum visitor. I will feel like I have achieved success when the patina is rubbed off parts of the bronze.

One more, a life-size bust of Galeamopus.

In addition to having these on display at the Cincinnati Museum Center, James will be producing these sculptures as limited editions. If you’re interested, please visit http://www.herrmannstudio.com/.