Table of old and new BYU specimen numbers

July 13, 2019

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?



[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.



  • 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.

11 Responses to “Table of old and new BYU specimen numbers”

  1. LeeB Says:

    A pity he didn’t think of writing the specimen number somewhere on the specimen.

  2. Mike Taylor Says:

    It may be that the specimen numbers are written on at least some of the specimens. That’ll be something to check for if I ever get back out to Utah.

  3. Jurassosaurus Says:

    I haven’t looked through all the comments on this series, but I was wondering if someone was going to point out how flawed Jensen’s approach was. It reminds me a lot of Robert Bakker’s earlier work, chasing the limelight more than the science. Judging from the recounting of the discovery of these three sauropods, it sounds like Jensen suffered from a bit of that too.

  4. Mike Taylor Says:

    I’m not sure how fair that is, Jurassosaurus. Of course I never knew Jensen — he died before my interest in palaeo because serious — but my very considerable reading around Supersaurus doesn’t really indicate a publicity hound: just someone whose passion for the practical side of palaeo left him short of attention or concentration for the academic side.

  5. Jurassosaurus Says:

    Limelight was not the best choice of words here. More like, he seemed more excited about finding the next big thing, than dealing with the more tedious aspects of the descriptive process (hence Reader’s Digest over a scientific journal).

    Looking deeper into it, I think now that this quirk was just a byproduct of Jensen’s less than traditional way of entering into paleontology. His son, Ronnie, provides a remarkably detailed website dedicated to his dad’s life and work ( According to the site, Jensen did not like having his writing critiqued, and this appears to have slowed his publication rate down a lot. His sensitivity to these criticisms really seemed to have grated on him as he got older.

    It’s unfortunate that he viewed himself as not a paleontologist towards the end. He definitely was. If anything, he helped show that there are multiple avenues available to enter into paleontology.

  6. Mike Taylor Says:

    Wow, I didn’t know about that Dinosaur Jim website. What a find! Thanks for the tip.

  7. Mike Taylor Says:

    In terms of what kind of a person Jensen was, I was touched to read this 1982 letter to the New York Times:

    Several years ago, my first-grade students collected about $24 to send to James Jensen so that he could continue digging for the remains of Supersaurus.

    In addition, they each enclosed an illustrated story about dinosaurs. ”Dinosaur Jim,” as he signed himself, replied to every child. It was obvious that his replies related directly to each one’s story. A whole new crop of paleontologists is in the making, and they all look up to Dinosaur Jim. BETTY HOROWITZ Delran, N.J.

  8. Mike Taylor Says:

    Here is another telling insight. Writing for the New York Times in 1982, John Noble Wilford describes time spent with Jensen. After a digression into then then-newish theory of dinosaur endothermy, the article return to Jensen with this:

    ”I leave the theories to the armchair scientists,” Jim Jensen remarked on the drive to the Blues. ”What I know is how to dig up dinosaurs.”

  9. Emanuel Says:

    this could be of interest concerning old and new specimen numbers:

  10. Mike Taylor Says:

    Appreciated, Emanuel!

  11. […] so the series continues: part 9, part 10 and part 11 were not numbered as such, but that’s what they were, so I am picking up the […]

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