| Ultrasaurus | |
|---|---|
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | †Sauropodomorpha |
| Clade: | †Sauropoda |
| Genus: | †Ultrasaurus Kim, 1983[1] |
| Species: | †U. tabriensis |
| Binomial name | |
| †Ultrasaurus tabriensis Kim, 1983[1] | |
| Synonyms | |
| |
Ultrasaurus (meaning "ultra lizard"[2]) is agenus ofsauropod dinosaur discovered by Haang Mook Kim in South Korea. However, the name was first used unofficially (as anomen nudum) in 1979 byJim Jensen to describe a set of giantdinosaur bones he discovered in the United States. Because Kim published the name for his specimen before Jensen could do so officially, George Olshevsky renamed the specimen asUltrasauros. Jensen's giant sauropod was later found to be achimera, and thetype remains are now assigned toSupersaurus.
A collection of bones discovered byJim Jensen, ofBrigham Young University, at theDry Mesa Quarry,Colorado were originally believed to belong to the largest dinosaur ever. Jensen informally called this supposedly new dinosaur "Ultrasaurus", and this name was widely used by the press and in scientific literature as anomen nudum (informal name lacking an actual scientific description).[3]
In 1983, Haang Mook Kim published a paper describing a different specimen representing a new dinosaur species, which he namedUltrasaurus tabriensis, because he believed it was bigger thanSupersaurus.[1] However, Kim's assessment was incorrect; his dinosaur was much smaller than he believed, because he mistook a partialhumerus for anulna.[4] Since Kim was the first to publish the nameUltrasaurus, the name officially applied to theSouth Korean sauropod, and could no longer be used as an official name for Jensen's giant specimen.[3]
Jensen published a paper describing his original discovery in 1985,[5] but since the nameUltrasaurus was already in use (or "preoccupied"), George Olshevsky renamed it toUltrasauros in 1991 based on Jensen's suggestion.[6] However, Jensen's discovery was a chimera, as the collection offossils came from two different dinosaur generaSupersaurus andBrachiosaurus, both of which already had names. So the new name,Ultrasauros, is now considered as a junior synonym for the dinosaur officially known asSupersaurus.[7]
Ultrasaurus lived 100 to 110 million years ago, during theAptian andAlbianstages of theEarly Cretaceous. It is known from the holotypeDGBU-1973, which consists of part of the dinosaur's front leg or “hand” (humerus) initially mistaken as the upper (proximal) end of the right medial forearm (ulna), andDGBU-1978-A, a single tailbone (vertebrae) from theGugyedong Formation, belonging to the Hayang Group.[1][4]
Kim'sUltrasaurus is currently anomen dubium. Not enough is known about the specimen to formally assign it to a specificfamily of sauropods.[4]
