Whatever happened to Ultrasauros?

Brian Curtice

I have been perusing through the archives of this list and noted some time ago a thread regarding the status of Ultrasauros macintoshi, Supersaurus vivianae and Dystylosaurus edwini. Myself and 2 colleagues (Ken Stadtman and Linda Curtice) have a paper that will be appearing in the Continental Jurassic Symposium Volume (probably out as I type). Linda and I also gave a poster at SVP regarding these taxa. The story on these taxa is: the holotype dorsal vertebra of Ultrasauros macintoshi (BYU 9044) clearly belongs to a LARGE diplodocid while the referred scapulocoracoid (BYU 9462) is brachiosaurid. Regarding the latter element, the scapula isn't even as thick or wide as the thickest and widest scapulae from the Tendaguru beds, and BYU 9462 is only marginally longer. Even worse for it, the coracoid is substantially smaller than that found with the holotype material for Brachiosaurus altithorax, leading myself and my colleagues to assign the scapulocoracoid to Brachiosaurus sp. for now. [Thus Ultrasauros becomes a junior synonym of Supersaurus -- ed.] We have a publication nearing completion that addresses Brachiosaurus in great detail by fully describing the Brachiosaurus material from North America that has been languishing on shelves throughout the United States for many years. The last hurdle will be surmounted during a comparative trip to Europe this summer.

Supersaurus vivianae is definitely a valid sauropod. The "Osteology of Supersaurus vivianae Jensen, 1985" nears completion, within it are descriptions of many new elements that have been prepared (and recognized) in the last 2 years. The referral of the holotype dorsal vertebra of Ultrasauros to Supersaurus led to some sticky nomenclatural problems (as well as explaining to Jim Jensen why I chose to abolish the brachiosaurid charged name Ultrasauros). However, by referring the Ultrasauros type dorsal to Supersaurus many of the Dry Mesa mysteries (like the BIG pelvis) were solved. My productivity on getting my thesis material out has been hampered by having to take Human Gross Anatomy (doh!) but within a year I should be unveiling the diplodocid, Madagascar and Lower Cretaceous sauropod extravaganza, which should provide all sauropod fans as much glee as it provided me!

As for Dystylosaurus, in my thesis I question its validity, and am now 90% convinced that it, too, belongs to Supersaurus. However, until I formally synonymize Dystylosaurus with Supersaurus I suppose it must remain considered a valid genus.