There are more dinosaurs today than there were when I was a kid. A new species is discovered about every six weeks. In the tradition of paleontology, whoever finds the bones for the first time names the new species. This may sound easy, but often, the dinosaur must be named when only a single bone has been found, and the name is only valid if the bone really does not belong to an already known dinosaur and if the name is original.
In 1976, James A Jensen, found a few bones in western Colorado. Jensen named the Ultrasaurus in 1985 (meaning "Ultra lizard"). Only a shoulder blade (scapula), some vertebrae, and a partial hip have been found. After further study, these fossils may not belong to a single dinosaur at all, but are probably bits of a huge Brachiosaurus (the enormous shoulder bone) and a Supersaurus (the vertebrae).1
Haang Mook Kim found a huge bone in 1983. In thinking the bone was an ulna (a lower arm bone), the dinosaur was assumed to be gigantic, and of the same type of dinosaur discovered earlier by Jensen. Even though the bone turned out to be a partial humerus, the dinosaur is still called ultrasaurus.2
So the ultrasuarus may or may not be a species of dinosaur, or at least not what it was orginally thought to be. For some reason, the odd stories of dinosaur discovery and naming reminds me of internet software. It all sounded so scientific and precise when I first learned about it, but over the years, it turns out that we really know very little. Stories about old bones and new software reflect the humans who create them.
1Enchanted Learning's ultrasaurus pages
ultrasaurus , more
detail from Dr Timothy J. Williams