Supersaurus timeline

July 17, 2019

The history of Supersaurus — and its buddies Ultrasauros and Dystylosaurus — is pretty complicated, and there seems to be no one source for it. But having read a lot about these animals in the process of writing eleven mostly pretty substantial posts about them, I feel like I’m starting to put it all together. This post is an attempt at recognising the landmarks in this history, in chronological order. Please leave a comment if you find a mistake or if I missed anything.


1943 — Sawmill operator Eddie Jones and his wife Vivian are prospecting for uranium during WWII. They find a brachiosaur skeleton in an advanced state of erosion at Potter Creek in the Uncompahgre Upwarp (1987:592). (Jensen 1985a:697 says the humerus was also collected in this year, but that is contradicted by other accounts.)

1955 — Eddie and Vivian Jones collect the brachiosaur humerus and donate it to the Smithsonian Institition (George 1873b:53), where it is accessioned as USNM 21903 and put on display some time before March 1959 (Anonymous 1959).

USNM 21903, a left humerus of ?Brachiosaurus altithorax, discovered by Eddie and Vivian Jones. From the NMNH’s specimen gallery page, which gives the collection date as 1955. When I first saw this specimen, my gut reaction was that it was not slender enough to be Brachiosaurus, but note that the midshaft is very extensively restored. It may be that the intact bone was longer than the version we now see.

1958 — Jensen sees the Smithsonian humerus and finds the Jones family, who take him to the humerus location in Potter Creek and to three other Uncompahgre fossil localities (Jensen 1985a:697).

1964 — Jensen makes his first collection from the Uncompahgre Upwarp (Jensen 1985b:710).

1971 — Jensen sees a theropod toe bone at the Joneses’ home and asks where they found it. They tell him “On the Uncompahgre” (George 1973b:53), i.e. probably specifically from Dry Mesa, awakening his interest in that quarry.

1972 — In April (George 1973b:53), Jensen makes his first collection of material from Dry Mesa, one of the Uncompahgre localities found by the Joneses (Jensen 1985a:697).

In August (George 1973b:51-52) a large sauropod pelvis is found. This seems to have been the first element found that hinted at a very large sauropod at Dry Mesa (George 1973b:52-53).

Jensen displays the first Dry Mesa pelvis, still in the ground, in a frame from the 1976 version of The Great Dinosaur Discovery [13m53s].

Later this year, the first large Dry Mesa scapulocoracoid is found (Jensen 1985b:717). This would later be referred to as the “first specimen” of Supersaurus (e.g. Jensen 1985a:figure 8), but it was the subsequently discovered “second specimen” that would become the holotype when the genus was formally named (Jensen 1985a:701).

[NOTE. I am increasingly concerned that this might be wrong, and that the first scapulocoracoid found might after all have become the holotype. How to establish this? I sense yet another blog-post incoming.]

This is also the date given in the Dystylosaurus systematic palaeontology of Jensen (1985a:707). This may be an error as it is seven years before the date given for Supersaurus and Ultrasaurus, both of which names were known long before that of Dystylosaurus. but Curtice and Stadtman (2001:33) corroborate this early date for the discovery of the Dystylosaurus vertebra, and the relatively low specimen number BYU 4503 perhaps also suggests early collection and accessioning.

1973 — First published accounts of the giant sauropod material from Dry Mesa. The earliest may be that of Jean George (1973a) in the Denver Post’s Empire Magazine, on May 13. This is subsequently condensed into an account (George 1973b) in Reader’s Digest for June (not August as stated by Jensen 1985b:717, who also mis-cites the title). This latter account may be responsible for coining the informal name “Supersaurus” (Jensen 1985b:717), which would later be confirmed as the scientific name. (“There ‘Supersaurus,’ as we will call him, now awaits an official name and taxonomic classification.” — George 1973b:53.)

On Tuesday 13 November, a one-hour film about the dinosaurs of Dry Mesa, The Great Dinosaur Discovery, premieres in Delta, Colorado (Herald 1973). It is to be aired on 225 public TV stations across the USA.

1976 — A shortened version of The Great Dinosaur Discovery is made available for schools. (At present, this is the only version we have access to.) In this version of the film (and presumably in the 1973 original, if the 1976 version was made only by cutting), the name “Supersaurus” is used informally, and a reconstruction of the animal [20 minutes in] shows it modelled after Brachiosaurus rather than a diplodocid.

1978 — Olshevsky (1991:139) gives this as the date of Jensen’s first informal use of the name “Ultrasaurus”, but this must be considered suspect as other sources say the key specimen of this genus was not discovered until 1979.

1979 — The brachiosaurid scapulocoracoid BYU 9462 (BYU 5001 of Jensen’s usage) is discovered and collected from the Dry Mesa Quarry (Jensen 1987:603 — although in this passage he incorrectly says the specimen number is BYU 5000). The discovery is witnessed by a Japanese film crew that is making a documentary about the Dry Mesa dinosaurs (Jensen 1985b:717). Jensen begins to refer to the specimen informally as “Ultrasaurus”.

Miller et al. (1991: figure 4b). “Loading plaster-jacketed bones at the Dry Mesa quarry, 1979. Left to right, Richard Jensen, Jim Jensen, Japanese TV crew.” It’s obvious from the shape of the plaster jacket that this is the “Ultrasaurus” scapulocoracoid BYU 9462.

This is the date given in the Ultrasaurus systematic palaeontology of Jensen (1985a:704).

This is also the date given in the Supersaurus systematic palaeontology of Jensen (1985a:701): “COLLECTOR.—James A. Jensen 1979”. This late date is surprising, as Supersaurus material was known as early as 1972. It may be that 1979 is the collection date of the second scapulocoracoid (BYU 9025, BYU 5500 of Jensen’s usage) that became the holotype.

1982 — Last collection of material considered for 1985 descriptive paper (Jensen 1985a:697).

Wilford (1982), in a popular article in the New York Times apparently written with Jensen’s collaboration, says that Supersaurus “may be an enlarged variation of brachiosaurus” and that Ultrasaurus “must have been even larger”, indicating that Supersaurus may still have been thought of as brachiosaurid well after the discovery of Ultrasaurus.

1983 — As of this date, approximately 100 tons of material collected by Jensen for BYU remains unprepared (Jensen 1985a:709).

Kim (1983) names a Korean sauropod Ultrasaurus tabriensis, intending it to be a new species of Jensen’s genus. However, since the name Ultrasaurus has not previously been formally published, Kim inadvertently preoccupies the name. (The Korean sauropod was thought enormous because of the size of its “ulna”; however, this bone is clearly a humerus, and of only moderate size for a sauropod. The taxon is generally considered undiagnosable, and the name therefore a nomen dubium.)

1985 — Jensen’s main descriptive paper (Jensen 1985a) is published, formally naming three new sauropod genera. Supersaurus (now considered to be of indeterminate family) is based on the scapulocoracoid BYU 9025 (BYU 5500 of his usage); Ultrasaurus (considered to be a brachiosaurid) is based on the posterior dorsal vertebra BYU 9044 (BYU 5000 of his usage) rather than the scapulocoracoid; and Dystylosaurus (which “no doubt represents a new sauropod family”) is based on the anterior dorsal vertebra BYU 4503 (BYU 5750 of his usage). This paper is accompanied by a broader overview of the Uncompahgre dinosaur fauna (Jensen 1985b).

1987 — Jensen’s second descriptive paper removes the large Dry Mesa cervical vertebra BYU 9024 (BYU 5003 of his usage) from Ultrasaurus and refers it to Supersaurus (Jensen 1987:600-602). It seems from this paper that he may have intended the Ultrasaurus scapulocoracoid BYU 9462 (BYU 5001) to be the holotype of that genus (Jensen 1987:603).

1988 — A large pelvis, BYU 13018, is found in Dry Mesa quarry (Wilford 1988, Miller et al. 1991:40). It will later be referred to Supersaurus (Curtice and Stadtman 2001:38-39), and is now on display at the North American Museum of Ancient Life.

1990 — In the landmark encyclopaedia The Dinosauria, McIntosh (1990) describes Supersaurus as a diplodocid (p391), Ultrasaurus (Jensen) as “a very large brachiosaurid” based on the type vertebra and referred scapulocoracoid (p384), and the Dystylosaurus vertebra as “clearly brachiosaurid” (p384).

1991 — McGowan (1991:118) originates the idea that Ultrasaurus massed 180 tonnes, based on its restoration as a brachiosaurid 1.32 times as large in linear dimension as the Berlin Giraffatitan brancai paralectotype MB.R.2181 (formerly HMN SII) whose mass Colbert (1962) had grossly overestimated at 78 tons.

Olshevsky (1991:139), recognising the preoccupation of the name Ultrasaurus by Kim’s (1983) genus, raises the replacement name Ultrasauros for Jensen’s genus, with Jensen’s blessing. He had originally suggested the replacement name Jensenosaurus, but Jensen disliked this and suggested the variant spelling that was ued instead (Curtice et al. 1996:87-88).

Miller et al. (1991:40) suggest that the holotype dorsal vertebra of Ultrasaurus (i.e. Ultrasauros) might by diplodocid, due to its similarity to the sacral vertebrae of the 1988 pelvis whose tall neural spines “most closely resemble the diplodocids”.

1995 — Curtice (1995), in an SVP abstract, reassigns to Supersaurus the clearly diplodocid caudal vertebra BYU 9045 (BYU 5002 of Jensen’s usage), which Jensen had assigned to Ultrasaurus.

The caudal vertebra BYU 9045 (BYU 5002 of Jensen’s usage), in (from left to right) posterior, right lateral, and anterior views. Modified from Jensen (1985a:figures 2E, 3E and 2D respectively), an including his original scalebars. These are consistent between the photos in posterior and lateral views, and if accurate indicate that the vertebra is 1.18 m in total height.

1996 — Curtice et al. (1996) persuasively show that the holotype of Ultrasauros, BYU 9044 (BYU 5000 of Jensen’s usage) is diplodocid, and conclude that it belongs to Supersaurus, making Ultrasauros a junior synonym.

2001 — Curtice and Kenneth (2001) show that the holotype of Dystylosaurus, BYU 4503 (BYU 5750 of Jensen’s usage) is diplodocid, and conclude that it, too, belongs to Supersaurus, making Dystylosaurus another junior synonym.

2003 — Curtice (2003), in a conference abstract, suggests tentatively that Supersaurus (into which he has already sunk Ultrasauros and Dystylosaurus) may itself be synonymous with Barosaurus.

2005 — A team from a the Wyoming Dinosaur Center announce in an SVP abstract and poster (Lovelace et al. 2005) a new specimen WDC DMJ-021 (“Jimbo”), which they refer to Supersaurus vivianae.

McIntosh (2005:73), in revising Barosaurus, is persuaded that Supersaurus is indeed a valid genus rather than merely a large species of Barosaurus.

2008 — The WDC team formally describe their referred Supersaurus specimen WDC DMJ-201 (“Jimbo”), providing a phylogenetic analysis that recovers Supersaurus (based on a compound BYU+WDC taxon) as more closely related to Apatosaurus than to Barosaurus.

2011 — Whitlock’s phylogenetic analysis of diplodocoids recovers Supersaurus as the most basal diplodocine (Whitlock 2011:figure 7), i.e. closer to Barosaurus than to Apatosaurus, but not very close to either.

2015 — Tschopp et al.’s phylogenetic analysis of diplodocoids codes the BYU and WDC Supersaurus individuals as separate OTUs and finds that they emerge as sister taxa (Tschopp et al. 2015:figure 118), corroborating Lovelace et al.’s referral of the WDC specimen to Supersaurus. They recover Supersaurus in a small clade with Australodocus and Dinheirosaurus near the base of diplodocinae: again, closer to Barosaurus than to Apatosaurus, but not very close to either.

2016 — In an SVPCA talk and abstract, Taylor and Wedel (2016) argue that BYU 2094, the large cervical vertebra usually considered to be part of the Dry Mesa Supersaurus, actually belongs to a large Barosaurus. If this is correct, then the concept of Supersaurus requires further revision.

2019 — In a seemingly endless series of blog-posts, Taylor and Wedel consider the history of Supersaurus and co., and the taxonomic implications of the BYU cervical belonging to Barosaurus.

References

Note: this is a unified bibliography for all the posts in the present series. It therefore includes references not cited in this post.

  • Anonymous. 1959. Brachiosaurus exhibit at the Smithsonian Institution. Nature 183(4662):649-650.
  • Colbert, Edwin H. 1962. The weights of dinosaurs. American Museum Novitates 2076:1–16.
  • Curtice, Brian D. 1995. A description of the anterior caudal vertebrae of Supersaurus vivianae. Journal of Vertebrate Paleontology 15(3):25A.
  • 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 Linda J. Curtice. 1996. Death of a dinosaur: a reevaluation of Ultrasauros macintoshi (Jensen 1985). Journal of Vertebrae Paleontology 16(3):26A.
  • 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.
  • Glut, Donald F. 1997. Dinosaurs: the Encyclopedia. McFarland & Company Inc., Jefferson. 1076 pp.
  • 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.
  • Hatcher, Jonathan B. 1901. Diplodocus (Marsh): its osteology, taxonomy and probable habits, with a restoration of the skeleton. Memoirs of the Carnegie Museum 1:1-63 and plates I-XIII.
  • The Herald. 1973. Film to Premiere on BYU Curator’s Great Dinosaur Discovery. The Herald, Provo, Utah, Sunday, November 11, 1973, p. 41.
  • Janensch, Werner. 1950. Die Skelettrekonstruktion von Brachiosaurus brancai. Palaeontographica (Suppl. 7) 3:97–103.
  • Jensen, James A. 1985a. Three new sauropod dinosaurs from the Upper Jurassic of Colorado. Great Basin Naturalist 45(4):697–709.
  • Jensen, James A. 1985b. Uncompahgre dinosaur fauna: a preliminary report. The Great Basin Naturalist 45(4):710-720.
  • 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. 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.
  • Lull, Richard S. 1919. The sauropod dinosaur Barosaurus Marsh. Memoirs of the Connecticut Academy of Arts and Sciences 6:1–42.
  • Marsh, Othniel Charles. 1891. Restoration of Triceratops. American Journal of Science, Series 3, 41:339–342.
  • McGowan, Christopher. 1991. Dinosaurs, Spitfires and Sea Dragons. Harvard University Press, Cambridge, MA. 365 pp.
  • McIntosh, John S. 1990. Sauropoda. pp. 345-401 in: D. B. Weishampel, P. Dodson and H. Osmólska (eds.), The Dinosauria. University of California Press, Berkeley and Los Angeles.
  • 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.
  • Olshevsky, George. 1991. A revision of the parainfraclass Archosauria Cope, 1869, excluding the advanced Crocodylia. Mesozoic Meanderings 2:1–196.
  • Paul, Gregory S. 2010. Dinosaurs: a Field Guide. A. & C. Black Publishers ltd. London, UK. 320 pp.
  • Taylor, Michael P.  2009.  A re-evaluation of Brachiosaurus altithorax Riggs 1903 (Dinosauria, Sauropoda) and its generic separation from Giraffatitan brancai (Janensch 1914). Journal of Vertebrate Paleontology 29(3):787–806.
  • Taylor, Michael P. 2010. Sauropod dinosaur research: a historical review. pp. 361-386 in: Richard T. J. Moody, Eric Buffetaut, Darren Naish and David M. Martill (eds.), Dinosaurs and Other Extinct Saurians: a Historical Perspective. Geological Society of London, Special Publication 343. doi:10.1144/SP343.22
  • 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
  • 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.
  • 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
  • Wilford, John Noble. 1982. A new look at dinosaurs. New York Times, Feb. 7, 1982.
  • Wilford, John Noble. 1988. 2 teams find huge bones in West. New York Times, Sept. 6, 1988.

 

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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

 

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

 

 

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.

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

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

Here’s the story so far …

1. Jensen’s discoveries

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

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

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

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

2. Kim’s accidental Ultrasaurus

After Jensen had been using these names informally for some years, Kim (1983) named an indeterminate Korean sauropod as Ultrasaurus tabriensis. Based on the abstract (the only part of the paper in English, apart from the figure captions), Kim was aware of Jensen’s dinosaurs: “Judging by the large size of the ulna the animal may belong to the sauropod dinosaur, which is much bigger than Supersaurus. A new name Ultrasaurus tabriensis is proposed for the convenience of the further study.” While this does not quite go so far as to say that Kim considered the ulna to belong to the same genus as Jensen’s brachiosaur, it seems unlikely that he was aware of Supersaurus but not of Ultrasaurus, and landed independently on the latter name by coincidence. 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, the biggest brute ever. Denver Post, Empire Magazine. May 13, 1973.
  • George, Jean. 1973b. Supersaurus, the biggest brute ever. Reader’s Digest (June 1973):51–56.
  • Glut, Donald F. 1997. Dinosaurs: the Encyclopedia. McFarland & Company Inc., Jefferson. 1076 pp.
  • Jensen, James A. 1985. Three new sauropod dinosaurs from the Upper Jurassic of Colorado. Great Basin Naturalist 45(4):697–709.
  • Jensen, James A. 1987. New brachiosaur material from the Late Jurassic of Utah and Colorado. Great Basin Naturalist 47(4):592–608.
  • Kim, 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

 

Next to Charles Knight, the Czech painter Zdeněk Burian was arguably the most influential and important of the early palaeoartists. His dinosaurs tend to have a stately quality that’s very much at odds with our post-Dinosaur Renaissance sensibilities, but which has its own charm. Here’s arguably his most famous (and incorrect) piece, the snorkelling brachiosaurs:

The reason I mention him now is that I recently stumbled across the Paleo Porch site containing decent-quality images of his artworks. For some reason, Burian’s work always seems to appear in low-quality, small-size scans which do nothing to mitigate his tendency to use muted colours and low contrasts. So it’s nice to see his work looking relatively bold and clear.

Here’s his Brontosaurus, too:

There’s a ton we could criticise about both of these pieces; but we don’t have to do that. Instead, let’s just bask in the sheer dinosaurosity of these classic pieces.