In Depth
Due to the incomplete nature of the holotype fossils, Ultrasaurus is today seen as a dubious genus of sauropod dinosaur, given that it would be near impossible to attribute further remains to the genus. Ultrasaurus is actually more famous for forcing a naming change in a North American genus of diplodocid dinosaur. In 1985 the palaeontologist James A. Jenson named three new sauropods from fossils recovered from the North American Morrison Formation. Unaware of Kim’s description of a South Korean sauropod in 1993, Jenson named one of his sauropods Ultrasaurus macintoshi. Because Kim named his sauropod first, his description had naming priority, and in 1991 Ultrasaurus macintoshi was renamed Ultrasauros macintoshi. This is now a moot point however as after this Ultrasauros was discovered to be a fossil chimera composed of diplodocid and brachiosaurid (in fact probably Brachiosaurus) fossils. On top of this the holotype fossil of Ultrasauros, a single vertebra was identified as not only belonging to another one of Jenson’s 1985 sauropods named Supersaurus, but actually belonging to the same individual Supersaurus that made up the holotype, making Ultrasauros a synonym to Supersaurus.
Back to the South Korean, Ultrasaurus there is speculation that this too may be synonymous with another sauropod genus, yet again, because of the indeterminate nature of the fossils, it is uncertain to prove.
Further Reading
- Cretaceous dinosaurs from South Korea. - Journal of the Geological Society of Korea, 19(3): 115-126. - H. M. Kim - 1983.
