Ultrasauros

From Wikipedia, the free encyclopedia

Ultrasauros (formerly Ultrasaurus) is a currently invalid sauropod genus, with a complicated history. When a collection of bones from an apparently hitherto undiscovered dinosaur was found in 1979 at the Dry Mesa Dinosaur Quarry in Colorado by James A. Jensen, it was hailed as the largest dinosaur known to date. Unfortunately, the specimen was actually composed of bones from a Supersaurus and a large Brachiosaurus.

1 Jumbled bones
2 What's in a name?
3 References
4 External links

[edit] Jumbled bones

The backbone (a dorsal vertebra, labeled BYU 9044) that was used to define the new species actually belongs to a Supersaurus. In fact, it probably belongs to the original Supersaurus, which was discovered in the same quarry in 1972. Other bones, like the shoulder girdle (scapulocoracoid, BYU 9462) belong to a Brachiosaurus, possibly a large specimen of Brachiosaurus altithorax. (Curtice, 1996)

The Brachiosaurus bones indicate a large, but not record-breaking individual, a little larger than the Giraffatitan brancai in the Humboldt Museum of Berlin, which was the largest known dinosaur for decades. Larger specimens of Brachiosaurus are known from the Tendaguru Beds of Tanzania, in east Africa.

Originally, the bones were believed to represent a single dinosaur that was about 25 to 30 meters (80 to 100 feet) long, 8 meters (25 feet) high at the shoulder, 15 meters (50 feet) in total height, and weighing maybe 70 metric tonnes (75 tons). At the time, mass estimates ranged up to 180 tons, which placed it in the same category as the blue whale and the equally problematic Bruhathkayosaurus. More current estimates are far more conservative.

[edit] What's in a name?

The naming of ultrasauros has a similarly complicated history. Ultrasaurus was the original choice, and was widely used by the media after the discovery in 1979. However, the name of a new species must be published to become official.

Before Jensen published his finding in 1985, the paleontologist Haang Mook Kim used the name Ultrasaurus in a 1983 publication to describe what he believed was a giant dinosaur in South Korea. This was a different, much smaller dinosaur, due to a femur mistaken for a humerus. While the logic of naming was incorrect, the Ultrasaurus from Kim's find became regarded as a legitimate, if dubious genus.

So when James A. Jensen finally published a paper describing his find in 1985, he was forced to choose a new name (in technical terms, his original choice was "preoccupied"). In 1991, at his suggestion, George Olshevsky changed one letter, and renamed it Ultrasauros.

When it was discovered that the new name referred to bones from two separate, and already known species, the name Ultrasauros became a junior synonym for Supersaurus. Since the bones from the Brachiosaurus were only used as a secondary reference for the new species, Ultrasauros is not a junior synonym for Brachiosaurus.

[edit] References

"Three new sauropod dinosaurs from the Upper Jurassic of Colorado", by James A. Jensen (1985). Great Basin Naturalist, issue 45, pages 697 to 709.

"A re-assessment of Ultrasauros macintoshi (Jensen, 1985)", by Brian Curtice, Ken Stadtman, and Linda Curtice (1996). The Continental Jurassic: Transactions of the Continental Jurassic Symposium, Museum of Northern Arizona Bulletin number 60, pages 87 to 95, edited by M. Morales.