SuperBarosaurus and Dystylosaurus

I have discovered some very interesting news in the Diplodocid camp lately. An SVPCA abstract by Mike Taylor and Matt Wedel (here, on pg. 30) described some BYU cervicals which belong to Barosaurus. We all know and love Barosaurus of course. From the mighty AMNH 6341, the quintessential Barosaurus specimen:

Fig. 1. AMNH 6341. Image copyright the AMNH.


to ROM 3670, the largest known Barosaurus specimen, at roughly 27m long.

Fig. 2. ROM 3670, skeletal restoration by Scott Hartman.


In this abstract, they describe a set of three dorsal vertebrae from BYU quarry 3GR (which is what I will refer to the specimens as from now on). These vertebrae are of uncertain position exactly, but based on neural spine bifurcation the last one (vertebra C) belongs to C9-C11. The C9-C11 of AMNH 6341 are 685, 737, and 775mm long, respectively.

Image result for amnh 6341

Fig. 3. Left column, C9-12. right column, C14-16. From Taylor & Wedel, 2013b.


Vertebra C from BYU 3GR is 1220mm. This vertebrae is 1.57 to 1.78 times longer than that of AMNH 6341, and belongs to a neck 13.3-15.1m long, as the AMNH Barosaurus has an 8.5m neck. This implies a Barosaurus 33 to 37.38m long. That’s a huge size leap for Barosaurus.

Incredibly though, the story doesn’t end there. BYU 9024 is a very large cervical (in fact it’s the longest Sauropod cervical known, at 1330mm). This cervical was originally referred to Supersaurus, but it shares the same characters with Barosaurus as those of BYU 3GR (elongation, broad prezygapophyseal facets, “hinged” prezygapophyseal rami with dorsomedial and dorsolateral faces, narrow, posteriorly set diapophyses bearing posterior tubercles, and wing-like postzygadiapophyseal laminae). This vertebra (also potentially C9) is twice as long as the C9 of AMNH 6341. Thus this implies a neck twice as long as AMNH 6341, at 17m. Let me reiterate that: 17 METERS! So a nice quick scale up of AMNH 6341 to a 17m long neck yields a total length of 42m for BYU 9024! Just some perspective on this, the total length of Puertasaurus (widely considered to be one of the largest Dinosaurs) is 32m (per my skeletal, see below).

Puertasaurus reuili Paper Me

Fig. 4. Skeletal restoration of Puertasaurus reuili. Scale bar equals 4m.


And here is one of Scott Hartman’s lovely Barosaurus skeletals scaled to a 17m neck.

Super Barosaurus

Fig. 5. Barosaurus with a 17m neck. Chart created by RandomDinos.


Super Barosaurus is awesome, but this isn’t the only news from this abstract. In the abstract, they also state:

Dystylosaurus has also been referred to Supersaurus. Although the holotype and only vertebra is clearly a diplodocid anterior dorsal (it has dual centroprezygapophyseal laminae, a large cotyle and “drooping” parapophyses), its tall, unsplit neural spine and pronounced ventral keel prevent assignment to any known diplodocid. It may be a valid, distinct genus.”

Now, as we all know, Dystylosaurus is a part of the mess that is the Dry Mesa Sauropods. The three, Supersaurus, Ultrasauros, and Dystylosaurus were all described as separate genera, until Curtice, Stadtman, & Curtice (1996) and Curtice & Stadtman (2001) reanalyzed the remains and found that Dystylosaurus was likely Supersaurus, and the holotype dorsal of Ultrasauros actually belongs to Supersaurus, and the giant Ultrasauros scapulocoracoid is Brachiosaurus (which I don’t agree with, but that’s for another time). However, a Taylor & Wedel show, Dystyosaurus can’t be presently referred to any existing Diplodocid species, and may once more be distinct. Wooo! #Dystylosaurushype!

What do you guys think? Let me know below.

References


  1. Taylor, M.P., & Wedel, M. J. (In press). “How big did Barosaurus get?” SVPCA Liverpool 2016 Abstracts: 30.
  2. Curtice, B., Stadtman, K., and Curtice, L. (1996) “A re-assessment of Ultrasauros macintoshi (Jensen, 1985).” Pp. 87-95 in M. Morales (ed.), The Continental Jurassic: Transactions of the Continental Jurassic Symposium, Museum of Northern Arizona Bulletin number 60.
  3. Curtice, B.; Stadtman, K. (2001). “The demise of Dystylosaurus edwini and a revision of Supersaurus vivianae“. In McCord, R.D.; Boaz, D. Western Association of Vertebrate Paleontologists and Southwest Paleontological Symposium – Proceedings 2001. Mesa Southwest Museum Bulletin. 8. pp. 33–40.

 

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