Supersaurus, Ultrasaurus and Dystylosaurus in 2019, part 3: the material of Supersaurus

June 17, 2019

Having surveyed what we know from the published literature about Jensen’s Big Three sauropods, and what Matt and I concluded about its big cervical BYU 9024, and having thought a bit more about the size of the BYU 9024 animal, we’re getting to the point where we can consider what all this means for Jensen’s taxa.

The Supersaurus pelvis BYU 13018 in right lateral view, at the North American Museum of Ancient Life (NAMAL). Signage reads: “Supersaurus pelvis. In 1988 the pelvis of Supersaurus was discovered at Dry Mesa Quarry. Brian Versey, Cliff Miles and Ken Stadtman of Brigham Young University’s Earth Science Museum found the pelvis while they were trying to close the quarry for the season. The discovery generated a huge media event, making headlines around the world. This pelvis is the largest dinosaur bone complex ever discovered. It is on display here for the very first time. Specimen on loan from Brigham Young University’s Earth Science Museum. Late Jurassic/Early Cretaceous (about 144 million years ago)

As Curtice and Stadtman (2001:36-39) pointed out, Supersaurus is actually known from quite a lot of material, all assigned to the holotype individual. I’ll quote them at length rather than paraphrasing, but if you want a tabular summary, you can skip the quote and pick up down below.

Supersaurus vivianae roll call

The name “Supersaurus” first appeared in a Reader’s Digest article (George, 1973) describing a pair of 8′ long scapulocoracoids uncovered from Dry Mesa Dinosaur Quarry near Delta, Colorado. When formally described (Jensen, 1985) a number of elements were referred to the holotype including the left scapulocoracoid discovered in 1972 (BYU 9025), a right scapulocoracoid (BYU 12962), a right ischium (BYU 12946), a distal proximal caudal vertebra (BYU 12843) and 12 articulated mid-caudal vertebrae (BYU 9084). An additional caudal vertebra (BYU 9077) is referred to (and figured as) Supersaurus in the text of Jensen (1985). The specimen numbers used in Jensen (1985), no longer valid, have created confusion in the literature (e.g., Paul, 1988) and thus current BYU specimen numbers are used here throughout.

Jensen (1987) later referred a mid-cervical vertebra (BYU 9024) and Curtice and Curtice (1996) a proximal caudal vertebra (BYU 9045), both originally assigned to Ultrasauros, to Supersaurus. Numerous additional elements belong to Supersaurus, including a left ischium (BYU 12555), which is clearly the mate to the referred right ischium (BYU 12946), a right pubis (BYU 12424), a carpal (BYU 12390), a phalanx (BYU 9000), a left ulna (BYU 13744), at least five caudal vertebrae (BYU 4839, 9045, 12639, 12819, 12843) and a pelvis (BYU 13018) consisting of a left ilium and four sacral vertebrae.

Jensen never referred the two Supersaurus scapulocoracoids to the same individual due to a 260 mm discrepancy in length. Stripping away the paint and resin on BYU 9025 revealed the proximal end had been inadvertently lengthened during preservation. Close examination of the actual bone surface nets a total scapulocoracoid length less than 50 mm longer than BYU 12962, an amount easily accounted for by scapular variation and thus here both are referred to the same individual. Concerning the large brachiosaur scapulocoracoid (BYU 9462) Jensen (1985) listed as part of the material belonging to Ultrasauros, it is demonstrably smaller than the largest Tendaguru scapula and has been referred to Brachiosaurus sp. (Curtice and Curtice, 1996; Curtice et al., 1996). As such all exceptionally large sauropod elements from Dry Mesa Dinosaur Quarry can be referred to one of two individuals, one a Supersaurus and one a Brachiosaurus.

A dorsal vertebra (BYU 9044) referred to Supersaurus (Curtice and Curtice, 1996; Curtice et al., 1996) results in Ultrasaurus macintoshi becoming a junior synonym of Supersaurus vivianae, as BYU 9044 was the type specimen of Ultrasauros. A second dorsal vertebra, BYU 12814, is also here referred to Supersaurus based on its similarities to BYU 9044. All of the three large dorsal vertebrae mentioned herein were found within the confines of the paired Supersaurus scapulae further strengthening the suggestion all of the large diplodocid elements belong to a single individual.

(Yes, it really does say “a distal proximal caudal vertebra”.)

Curtice and Stadtman say that the pelvis consists of left ilium plus four sacral vertebrae; but as the photo above clearly shows, it is the right ilium that is preserved.

Here is a summary table, in standard anatomical order:

Specimen Element Referred by
9024 Mid-cervical vertebra Jensen 1987
12814 Anterior dorsal vertebra Curtice & Stadtman 2001
9044 Posterior dorsal vertebra Curtice et al. 1996
13018 Pelvis (right ilium, four sacral vertebrae) Curtice & Stadtman 2001
9045 Proximal caudal vertebra Curtice & Curtice 1996
12843 “Distal proximal” caudal vertebra Jensen 1985
9084 Twelve articulated mid-caudal vertebrae Jensen 1985
9077 Caudal vertebra Jensen 1985
4839 Caudal vertebra Curtice & Stadtman 2001
9045 Caudal vertebra Curtice & Stadtman 2001
12639 Caudal vertebra Curtice & Stadtman 2001
12819 Caudal vertebra Curtice & Stadtman 2001
12843 Caudal vertebra Curtice & Stadtman 2001
9025 Left scapulocoracoid Holotype
12962 Right scapulocoracoid Jensen 1985
13744 Left ulna Curtice & Stadtman 2001
12390 Carpal Curtice & Stadtman 2001
12424 Right pubis Curtice & Stadtman 2001
12946 Right ischium Jensen 1985
12555 Left ischium Curtice & Stadtman 2001
9000 Phalanx Curtice & Stadtman 2001

This is an impressively complete specimen — especially for a giant sauropod, as these tend only to survive in the form of isolated elements.

But is it really one specimen? That’s the subject of the next post.

(This post is rather slender by recent standards. That’s because I accidentally hit Publish when it was only half written. Rather than leave it to slowly change as I write more, I think it’s better to let this first half stand as its own post, and write the rest as its own post next time.)

 

References

  • 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.
  • 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.

 

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4 Responses to “Supersaurus, Ultrasaurus and Dystylosaurus in 2019, part 3: the material of Supersaurus


  1. […] scapulae. But the followup paper on Dystylosaurus (Curtice and Stadtman 2002) does. As noted in part 3 of this series, the “Supersaurus vivianae roll call” section […]


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


  3. […] 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 […]


  4. […] 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. […]


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