Last time, we reviewed what’s known about Jensen’s three giant sauropods based on published papers (and one abstract). This time, I want to talk a bit about what Matt and I have discovered, and intend to publish when we get around to it.

The Three Baro Jacket

It all followed on from our work on Barosaurus (which for now remains available only as a preprint, becalmed as it is in the peer-review doldrums — mostly my fault). Because of that, we were on the alert for Barosaurus material when we were travelling around Utah in Spring of 2016, and one of the first things we locked onto at the Brigham Young University’s Museum of Paleontology (BYU) was this:

We’ve been informally calling this “Three Baro Jacket”, or “3BJ” for short. But if we’re being formal, it’s specimen BYU 20815, being field jacket 3GR from BYU Locality 601 (The Jensen/Jensen quarry at Jensen, Utah), excavated in 1966. It also has an accession number, JJ/66 (which I didn’t realise was different from the specimen number).

Here it is being winched out of the ground at the Jensen/Jensen quarry, back in 1966 (photo courtesy of Brooks Britt):

This jacket contains — as our name for it suggests — three Barosaurus cervicals. The easiest way to see them is in 3D, using this red-cyan anaglyph, which shows the structure of the block much more informatively than the flat photo above:

(Do you have red-cyan anaglyph glasses? If not get some. They are dirt cheap, and will show you a whole world of morphology. For example, Amazon will send you ten pairs for $3.26, so you can keep two at home and two at work, and give half a dozen to your friends.)

For those stuck in the 2D world, these interpretive drawings should help to pick out the vertebrae from the matrix: they show individually the three vertebrae that we arbitrarily designated as A, B and C in that order.

Characters of Barosaurus cervicals

We spent some time looking pretty closely at these vertebra to figure out what they were — after all, the jacket wasn’t presented to us as “Here are some Barosaurus cervicals”. As we did so, we kept comparing the 3BJ vertebrae with photos we’d taken of the YPM and AMNH Barosaurus cervicals, and published illustrations. And as we did this, we discovered a whole set of distinctive characteristics of Barosaurus cervicals. We will properly describe and illustrate these characters another time, but to briefly summarise:

  • 1. Centra very long relative to vertebral height (measured at the posterior articular surface). This one will come as no surprise.
  • 2. Neural spine low and fairly smooth in profile.
  • 3. Postzygapophyses set forward slightly from posterior margin of centrum — as opposed to set well forward in brachiosaurs, or overhanging the posterior margin in apatosaurs.
  • 4. Parapophysis set much further forward than diapophysis, so that the cervical rib loop projects anteroventrally from the diapophysis.
  • 5. Cervical rib loop very thin anteroventrally (and lateromedially).
  • 6. Distinct hollow “thumb groove” between prezygapophyseal facet and pre-epipophysis.
  • 7. “U”-shaped notch in dorsal view where prezygapophyseal rami meet.
  • 8. Prezygapophyseal rami have two “faces” at right angles: one facing dorsomedially (bearing the prezgapophyseal facet), one facing dorsolaterally.
  • 9. Prezyagpophyseal rami very broad.
  • 10. Process projecting posteriorly from diapophysis.
  • 11. Prezyadiapophyseal lamina sweeps out smoothly to diaphophysis in dorsal view.

(These characters are all illustrated in our 2016 SVPCA talk: check the slides if you want to get a better handle on what we’re describing here. The reason I listed them in the slightly odd order above is so you can easily match them up with the slides.)

Now these vertebrae are well worthy of proper study and description in their own right, and we do plan to give them the attention they deserve. But for today’s story, they have done their part.

What is BYU 9024?

Now, here’s the thing. Literally a couple of yards away from the Three Baro Jacket in BYU collections sits the single longest vertebra of anything ever discovered: our old friend BYU 9024 (what Jensen called BYU 5003), which was originally assigned to Ultrasaurus (Jensen 1985), then reassigned to Supersaurus (Jensen 1987).

Mike compares Jensen’s sculpture of the big Supersaurus cervical BYU 9024 with the actual fossil.

And the more we looked at Barosaurus cervicals, then looked at BYU 9024, then looked back at Barosaurus, the more convinced we became that BYU 9024 is itself a Barosaurus cervical.

You would not immediately think this to look at the bone, as it’s pretty smashed up, and very difficult to interpret from photos, but this anaglyph will help:

As we discussed before, the posterior end looks much taller dorsoventrally than it should, because the postzygapophysis is folded upwards and the ventrolateral processes folded down.

Here’s what we see in BYU 9024 in terms of the characters we picked out from the 3BJ vertebrae. First, in left lateral view, with the characters highlighted in green:

  • 1. Centra very long relative to vertebral height (measured at the posterior articular surface).
  • 2. Neural spine low and fairly smooth in profile.
  • 3. Postzygapophyses set forward slightly from posterior margin of centrum.
  • 4. Parapophysis set much further forward than diapophysis, so that the cervical rib loop projects anteroventrally from the diapophysis.
  • 10. Process projecting posteriorly from diapophysis.

Now in anterodorsal view, with dorsal to the left:

  • 7. “U”-shaped notch in dorsal view where prezygapophyseal rami meet.
  • 8. Prezygapophyseal rami have two “faces” at right angles: one facing dorsomedially (bearing the prezgapophyseal facet), one facing dorsolaterally.
  • 9. Prezyagpophyseal rami very broad.

(It’s not easy to tell from this photo, but the broken-off area of flattish bone highlighted in the circle is part of the dorsolaterally-facing aspect of the prezygapophyseal ramus, where is it merging into the prezygadiapophyseal lamina.)

Three of the characters we saw in 3BJ we couldn’t determine in BYU 9024, due to breakage:

  • 5. Cervical rib loop very thin anteroventrally (and lateromedially).
  • 6. Distinct hollow “thumb groove” between prezygapophyseal facet and pre-epipophysis.
  • 11. Prezyadiapophyseal lamina sweeps out smoothly to diaphophysis in dorsal view.

But the morphology that’s preserved is certainly compatible with all of these. There are also a couple more characters in this vertebra that indicate that it’s Barosaurus, which we were not able to isolate in any of the 3BJ vertebrae:

  • A pair of posteroventrally directed accessory laminae radiating from the part of the centrum surface medial to the diapophysis. (These may be homologous with PCDLs but they seem to come out from under the PODL.)
  • It lacks paired foramina on the ventral surface separated by a midline ridge, as seen in Apatosaurus and WDC Supersaurus. (Thanks to David Lovelace from drawing our attention to that one in a comment on the last post!)

No one or two of these characters is a slam-dunk in isolation. But when you put them all together, they leave us pretty much 100% satisfied that BYU 9024 is a Barosaurus cervical.

How big was the BYU 9024 animal?

Before we say anything at all about this, please first hear our standard disclaimer: any size estimate based on a single bone is necessarily going to be wildly speculative, and could easily be a long way out in either direction.

That said, here’s the thinking behind our best guess.

First, what is the serial position of BYU 9024? We’d like to determine this by comparing with the cervical series of AMNH 6341, which is pretty well preserved — but unfortunately it has never been adequately illustrated and is now impossible to photograph as it is entombed below a walkway in the AMNH public gallery. Here’s the best published illustration, from McIntosh (2005:figure 2.1):

We judge it most similar to C9 or maybe C10, based largely on neural spine bifurcation and general proportions when corrected for distortion.

In AMNH, C9 is 685 mm long and C10 is 737 mm long (McIntosh 2005:table 2.1). Since BYU 9024 is 1370 mm in length, it is exactly twice as long as the C9 and 1.86 times as long as the C10.

I think I speak for all right-thinking people when I say holy crap.

If our identification of BYU 9024 as a C9 of Barosaurus is correct, then we are talking about an animal twice as large in linear dimension as the AMNH specimen whose cast looms over the rotunda (and the one at the Natural History Museum of Utah, which by eye is about the same size). Since the neck of the AMNH specimen is 8.5 m long (Wedel 2007:206–207), that would mean that the neck alone of BYU 9024 would have been 17 m long: longer than most complete sauropods and substantially taller than the mounted Giraffatitan skeleton in Berlin. The length of the whole animal is harder to predict, even if we assume isometry, but if Paul’s (2010:189) length estimate of 27 m for regular Barosaurus is correct, we’re probably looking at a total length exceeding 50 m.

This animal would, other things being equal, be eight times as massive (2 × 2 × 2) as the AMNH Barosaurus. There aren’t a lot of Barosaurus mass estimates out there, but Wedel (2005:217–221) did a lot of careful work to arrive at about 12 tonnes for the Diplodocus carnegii holotype CM 84, which is about the same size as the AMNH Barosaurus. If that’s right, then the BYU 9024 animal might have massed about 8 × 12 = 96 tonnes, which puts it right up there among the heaviest known sauropods: probably the heaviest represented by extant fossils, as the other strong contenders for that title are Maraapunisaurus and Bruhathkayosaurus, both known only from illustrations of now-destroyed specimens.

[UPDATE, the next day: see the next post for more on the serial position of the vertebra and the size of the animal.]

We presented most of this reasoning in our 2016 SVPCA talk, whose abstract and slides are online. (Sadly, there is no recording of the actual talk.)

Tune in for the post after that as we (finally!) reach the part promised by the title of this series, and consider where Jensen’s Big Three genera stand today.

 

References

  • 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.
  • McIntosh, John S. 2005. The genus Barosaurus Marsh (Sauropoda, Diplodocidae). pp. 38-77 in: Virginia Tidwell and Ken Carpenter (eds.), Thunder Lizards: the Sauropodomorph Dinosaurs. Indiana University Press, Bloomington, Indiana. 495 pp.
  • Paul, Gregory S. 2010. Dinosaurs: a Field Guide. A. & C. Black Publishers ltd. London, UK. 320 pp.
  • Wedel, Mathew J. 2005. Postcranial skeletal pneumaticity in sauropods and its implications for mass estimates. pp. 201-228 in Wilson, J. A., and Curry-Rogers, K. (eds.), The Sauropods: Evolution and Paleobiology. University of California Press, Berkeley
  • Wedel, Mathew J. 2007. Postcranial pneumaticity in dinosaurs and the origin of the avian lung. Ph.D dissertation, Integrative Biology, University of California, Berkeley, CA. Advisors: Kevin Padian and Bill Clemens. 290 pages.

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 widely circulated work 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).

“‘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. In fact, the “ulna” is a humerus, as shown by Lee et al. (1997).

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 2001:39 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 referred scapulocoracoid BYU 12962, 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 loan 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 (2001) 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 (2001) 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 this 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 they 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, giant of the giants. Denver Post,
    Empire Magazine. May 13, 1973, pp 14ff.
  • 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, Haang Mook. 1983. Cretaceous dinosaurs from South Korea. Journal of the Geological Society of Korea 19(3):115–126.
  • Lee, Yuong-Nam., S. Y. Yang and E. J. Park. 1997. Sauropod dinosaur remains from the Gyeongsang Supergroup, Korea; pp. 103–114 in S. Y. Yang, M. Huh, Y.-N. Lee and M. G. Lockley (eds.), International Dinosaur Symposium for Uhangri Dinosaur Center and Theme Park in Korea. Journal of Paleontological Society of Korea, Special Publication 2.
  • 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. 1991. 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

 

As regular readers will know, Matt and I have recently spent ten glorious days travelling the dinosaur museums of Utah, in a once-in-a-lifetime event that we have been calling the Sauropocalypse. In that time, we visited seven different museums and — this is the truth — had an absolutely fantastic time in all of them. One of the big reasons is of course the quality of their collections and galleries. But equally important is the welcome we got from our hosts at each of these places, and the help they all generously and cheerfully gave us.

Here’s where we visited, in chronological order, with a word of thanks to each host.

1. BYU Museum of Paleontology, Provo

IMG_3392

Mike compares Jensen’s sculpture of the big Supersaurus cervical BYU 9024 with the actual fossil.

At the amazing BYU — where we spent three full days, as it has almost certainly the largest collection of sauropod fossils anywhere in the world — our host was Brooks Britt. (Matt’s mentioned Brooks previously on this blog, as one of the most formative influences on his career: the person who put him onto pneumaticity.)

Brooks set us free in his collections and gallery with no restrictions. He had specimens fork-lifted down from high shelves for us, gave us a pallet lifter so we could move them around at will, and generally did everything he could to make our stay productive. He also took us out to lunch, twice: once at a cheap but delicious taco place, and once at a Brazilian eat-all-you-want barbecue place where I could happily have spent the entire afternoon.

2. The Prehistoric Museum, Price

IMG_2464

Matt inspects the beautifully preserved and prepared anterior cervicals of a Camarasaurus in the main gallery.

Our host at Price was occasional SV-POW! commenter Ken Carpenter, who also arranged for us to give a pair of talks at the museum in the evening. (Mine: Why giraffes have short necks. Matt’s: Why elephants are so small.) Ken gave us free reign to get in among the exhibits, and we took full advantage to make a potentially important discovery (to be discussed in a future post).

Ken also took us to see the CEUM collections, and invited us to take on a huge descriptive project, working on the PR2 brachiosaur. Sadly, that project is just too big for either of us. But there are individual elements within the PR2 collection that are of interest, and no doubt we’ll be posting more about those, too.

3. Dinosaur National Monument, Jensen

IMG_2603

Matt looms ominously over an Apatosaurus cervical in ventral view — or is it Camarasaurus?

Matt has already paid tribute to Dan Chure, our host up on the wall, who came in on his day off just to help us. An extraordinary host at an astonishing venue.

4. Utah Field House of Natural History, Vernal

IMG_2719

Diplodocus butt. Wedel for scale. He likes big butts and he cannot lie.

Here, we were hosted by Mary Beth Bottomley. She went beyond the call of duty in not only allowing us access to the prep room and collections, but helping us to take apart the shelving in collections so we could get better photos of a big, difficult-to-move specimen. Mary Beth was particularly interested in what we were working on, and will (I hope) now be a regular reader of this blog.

5. Dinosaur Journey, Fruita

IMG_2940

Mike, astonished by a particularly extreme apatosaur cervical. But then aren’t they all extreme?

We were, inadvertently, sensationally rude to our host, Julia McHugh. She’d arranged to take us for lunch, but Matt was so obsessed with the transit of Mercury across the sun that he completely forgot, and sent me off to get salads from Subway instead. (Note that I am making the point here that Matt forgot this arrangement. I make no comment on my own recall.) As a result, we cheated ourselves out of a BBQ lunch.

But Julia was great about it, and once again we were given free reign in collections. Matt and I were each able to make valuable observations, one for an already-in-progress paper and one for a new one.

6. Natural History Museum of Utah, Salt Lake City

IMG_3836

Barosaurus, an Allosaurus adult and several juveniles, and Mike.

Here, our host was Carrie Levitt. She welcomed us to the museum, gave us a tour of collections, left us to it, and … we spent almost the entire day in the public gallery instead! I did get a couple of nice photos of the holotype skulls of Kosmoceratops and Diabloceratops, but the truth is that the public gallery was so awesome, it just sucked us in.

But Carrie was great about it. Rather than resenting our having wasted her time in the collections orientation, she was just glad that we got useful observations out of the museum. (And we did. Matt and I can sometimes get so wrapped up in individual vertebrae that we forget they’re part of whole animals. The many fine mounted dinosaur skeletons at UMNH helped to redress this failing.)

7. North American Museum of Ancient Life, Thanksgiving Point

IMG_4641

Matt is attacked by a Utahraptor, but is all like “Am I bovvered?”. To be honest, I suspect he was all dinosaured out by this point.

On our last day — I had to be at the airport by 6pm — we went to NAMAL, We’d not been able to make contact with staff ahead of time, as Matt’s old contact seems to be no longer at the museum. But as we walked past the prep lab near the museum entrance, we saw some beautiful Barosaurus cervicals. As we stood gawping, Rick Hunter, inside the lab, recognised Matt and invited us in.

With no prior notice at all, Rick dropped what he was doing to help us out as we inspected their gorgeous material. That’s been really helpful as we’ve firmed up our ideas on what Barosaurus is. (And I hope we’ve helped them get a better handle on the serial positions of their vertebrae, too.)

In summary, pretty much everyone we met in Utah was super-helpful and super-nice. That also includes John and ReBecca Foster, who put us up for the night in Moab, the night before we went to Arches National Park. The people are one of three reasons why Utah is now my favourite US state. (The others are the sauropods, naturally, and the landscapes.)

Museum folks of Utah, we salute you!

UPDATE 19 May 2016

I belatedly realized that I caused some confusion in the original version of this post. This will hopefully sort things out:

NAMAL Barosaurus cervical with features labeled

The ventrolateral processes (1) are nothing new. As Ken Carpenter pointed out in a comment, Hatcher noted them back in 1901 in his monograph on Diplodocus carnegii. These are the features I describe below as being, “huge in Barosaurus, big in Diplodocus, small in Apatosaurus, and nonexistent in Haplocanthosaurus, Camarasaurus, and the brachiosaurids, at least from what I’ve seen.” To clarify: occasionally in camarasaurs and frequently in brachiosaurs you can trace a ridge along the ventrolateral margin of the centrum from the parapophysis to the cotyle. But these ridges are basically just the ‘corners’ of the centrum, leftover by the lateral and ventral waisting of the centrum – they do not project beyond the margin of the cotyle. In contrast, what I’ve been calling the ventrolateral flanges in diplodocids do project beyond the margins of the cotyle – they are additive structures, not just architectural leftovers. They also don’t vary much, other than to be more pronounced in more posterior cervicals.

The irregular ventral ridges (2) are a totally different thing. They’re on or near the sagittal midline of the centrum, usually restricted to the anteroposterior middle of the ventral centrum (so, about halfway between the condyle and the cotyle), and as my preferred term implies, highly variable among individuals and even among vertebrae in a series.

Hope that helps! (Original post starts below.)

– – – – – – – – – – – – – – – – – – – – –

2005-07-29 BYU 16918 Diplodocus left lateral

Back in 2005 I visited BYU while I was working on my dissertation. Back then I noted ventral ridges in a few diplodocine cervical vertebrae. (I hesitate to call such flimsy things ‘keels’.)

Up above is BYU 16918, a mid-to-posterior cervical vertebra of Diplodocus from the famous Dry Mesa Quarry. Here it is again in posterior view:

2005-07-29 BYU 16918 Diplodocus posterior view labeled

The things I have labeled VLF here are ventrolateral flanges, which are huge in Barosaurus, big in Diplodocus, small in Apatosaurus, and nonexistent in Haplocanthosaurus, Camarasaurus, and the brachiosaurids, at least from what I’ve seen. See this post for details. I know that the left VLF here looks like a second ridge, but the cotyle is broken off in such a way that we’re seeing the fossa just dorsal to the VLF margin. The ridge itself is skewed to the right, which could be natural or a result of taphonomy – as you can see from the photo at the top of the post, this vert has seen better days.

Here’s another Dry Mesa vert, BYU 11617, this time an anterior cervical of Barosaurus and in left lateral view:

2005-07-29 BYU 11617 Barosaurus left lateral

Again in right lateral view – on this side you can see the fossa in the VLF more clearly:

2005-07-29 BYU 11617 Barosaurus right lateral

And here’s the ventral view showing the ridge:

2005-07-29 BYU 11617 Barosaurus ventral view labeled

I noted these things in my notebook back when, filed them under, “Huh. How about that?” and went on with life.

Then last week Mike and I were at the North American Museum of Ancient Life in Lehi, Utah, and we saw this super-nice Barosaurus cervical on display in the prep lab (left ventro-lateral view). Check out the monster ventrolateral flanges, and the ridges between them at about mid-centrum.

IMG_4605

Here’s another view, a more square-on ventral this time:

IMG_4604

We owe a big thank you to Rick Hunter, who let us into the prep lab at the North American Museum of Ancient Life to see the Barosaurus material up close.

So what’s the deal with these ridges? I assume that they’re caused by pneumatic diverticula remodeling the ventral surface of the centrum. We know that such diverticula were down there because there are actual foramina on the ventral centrum in Supersaurus, many apatosaurines (Lovelace et al., 2008), many brachiosaurids, and probably loads of other things that haven’t been checked. Oddly enough, I’ve never seen the ridges in any of those other taxa. It seems that you get foramina or ridges, but not both. I have no idea what’s up with that – to paraphrase Neal Stephenson, Barosaurus cervicals are confections of air and marketing, and you’d think that if any sauropod would have straight-up foramina down there, it would be Barosaurus. But Barosaurus gets ridges and clunky old Apatosaurus gets foramina (sometimes, not all the time).

It’s a sick world, I tell you.

Reference

  • Lovelace, D. M., Hartman, S. A., & Wahl, W. R. (2007). 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.

IMG_4107

Seriously, Megatherium americanum, do you even lift?

Today, we were at the BYU Museum of Paleontology, which is in a ridiculously scenic setting with snow-capped mountains on the horizon in almost every direction.

IMG_2054

We got through a lot of good work in collections, and we’ll show you some photos from there in due course. But for today, here are a couple of pictures from the public galleries.

First, here in a single photo is definitive proof that the “Toroceratops hypothesis” is wrong:

DSCN0815

Say what you want about ontegenetic trajectories, that huge and well ossified Triceratops is not a juvenile of anything.

Good, glad we go that sorted out.

Meanwhile, at the even better end of the gallery, here is a very nice — and very well lit — cast of the famous articulated juvenile Camarasaurus specimen CM 11338 described by Gilmore (1925):

DSCN0842

Further bulletins as events warrant.

References

Gilmore, Charles W. 1925. A nearly complete articulated skeleton of
Camarasaurus, a saurischian dinosaur from the Dinosaur National
Monument, Utah. Memoirs of the Carnegie Museum 10:347-384.