Ultrasaurus
Encyclopedia
Ultrasaurus is a genus
of sauropod dinosaur
discovered by Haang Mook Kim in South Korea. However, the name was first used unofficially (as a nomen nudum
) in 1979 by Jim Jensen to describe a set of giant dinosaur bones he discovered in the United States. Because Kim published the name for his specimen before Jensen could do so officially, Jensen renamed his specimen Ultrasauros. Jensen's giant sauropod was later found to be a chimera
, and the type remains are now assigned to Supersaurus
.
, of Brigham Young University
, at the Dry 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 a nomen nudum (informal name lacking an actual scientific description).
In 1983, Kim Hang-mook published a paper describing a different specimen representing a new dinosaur genus, which he named Ultrasaurus tabriensis, because he believed it was an equally giant relative of Jensen's dinosaur. However, Kim's assessment was incorrect. His dinosaur was much smaller than he believed, because he mistook a partial humerus
for an ulna
. However, since Kim was the first to publish the name Ultrasaurus, the name officially applied to the small South Korea
n sauropod, and could no longer be used as an official name for Jensen's giant specimen.
Jensen published a paper describing his original discovery in 1985, but since the name Ultrasaurus was already in use (or "preoccupied"), his discovery was renamed in 1991 to Ultrasauros. However, Jensen also made a mistake. His discovery was a chimera; the collection of fossil
s came from two different dinosaur species, both of which already had names. So his new name, Ultrasauros, is now just an alternate name (junior synonym) for the dinosaur officially known as Supersaurus.
Kim's Ultrasaurus is currently nomen dubium
. Not enough is known about the specimen to formally assign it to a specific family of sauropods. It may even be a member of a known genus or species
, which would make the name Ultrasaurus a junior synonym as well.
and Albian
stages
of the early Cretaceous
. It is known from part of an upper forearm (humerus
), and some back bones (vertebrae).
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of sauropod dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
discovered by Haang Mook Kim in South Korea. However, the name was first used unofficially (as a nomen nudum
Nomen nudum
The phrase nomen nudum is a Latin term, meaning "naked name", used in taxonomy...
) in 1979 by Jim Jensen to describe a set of giant dinosaur bones he discovered in the United States. Because Kim published the name for his specimen before Jensen could do so officially, Jensen renamed his specimen Ultrasauros. Jensen's giant sauropod was later found to be a chimera
Chimera (paleontology)
In paleontology, a chimera is a fossil which was reconstructed with elements coming from more than a single species of animal. A now classic example of chimera is Protoavis.-List of paleontological chimeras:*Brontosaurus*Lametasaurus...
, and the type remains are now assigned to Supersaurus
Supersaurus
Supersaurus is a genus of diplodocid sauropod dinosaur discovered by Vivian Jones of Delta, Colorado, in the Upper Jurassic Morrison Formation of Colorado in 1972. The fossil remains came from the Brushy Basin Member of the formation, dating to about 153 million years ago...
.
Mistaken assessments
A collection of bones discovered by Jim JensenJames A. Jensen
James A. Jensen , was an American paleontologist. His extensive collecting program at BYU in the Utah-Colorado region which spanned 23 years was comparable in terms of the number of specimens collected to that of Barnum Brown during the early 20th century. He was given the name "Dinosaur Jim"...
, of Brigham Young University
Brigham Young University
Brigham Young University is a private university located in Provo, Utah. It is owned and operated by The Church of Jesus Christ of Latter-day Saints , and is the United States' largest religious university and third-largest private university.Approximately 98% of the university's 34,000 students...
, at the Dry Mesa Quarry
Dry Mesa Quarry
The Dry Mesa Dinosaur Quarry is situated in southwestern Colorado, USA, near the town of Delta. Its geology forms a part of the Morrison Formation and has famously yielded a great diversity of animal remains from the Jurassic Period, among them Ceratosaurus, Supersaurus, and Torvosaurus...
, Colorado
Colorado
Colorado is a U.S. state that encompasses much of the Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains...
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 a nomen nudum (informal name lacking an actual scientific description).
In 1983, Kim Hang-mook published a paper describing a different specimen representing a new dinosaur genus, which he named Ultrasaurus tabriensis, because he believed it was an equally giant relative of Jensen's dinosaur. However, Kim's assessment was incorrect. His dinosaur was much smaller than he believed, because he mistook a partial humerus
Humerus
The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow....
for an ulna
Ulna
The ulna is one of the two long bones in the forearm, the other being the radius. It is prismatic in form and runs parallel to the radius, which is shorter and smaller. In anatomical position The ulna is one of the two long bones in the forearm, the other being the radius. It is prismatic in form...
. However, since Kim was the first to publish the name Ultrasaurus, the name officially applied to the small South Korea
South Korea
The Republic of Korea , , is a sovereign state in East Asia, located on the southern portion of the Korean Peninsula. It is neighbored by the People's Republic of China to the west, Japan to the east, North Korea to the north, and the East China Sea and Republic of China to the south...
n sauropod, and could no longer be used as an official name for Jensen's giant specimen.
Jensen published a paper describing his original discovery in 1985, but since the name Ultrasaurus was already in use (or "preoccupied"), his discovery was renamed in 1991 to Ultrasauros. However, Jensen also made a mistake. His discovery was a chimera; the collection of fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s came from two different dinosaur species, both of which already had names. So his new name, Ultrasauros, is now just an alternate name (junior synonym) for the dinosaur officially known as Supersaurus.
Kim's Ultrasaurus is currently nomen dubium
Nomen dubium
In zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application...
. Not enough is known about the specimen to formally assign it to a specific family of sauropods. It may even be a member of a known genus or species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
, which would make the name Ultrasaurus a junior synonym as well.
Description
Ultrasaurus lived 100 to 110 million years ago, during the AptianAptian
The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous epoch or series and encompasses the time from 125.0 ± 1.0 Ma to 112.0 ± 1.0 Ma , approximately...
and Albian
Albian
The Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early/Lower Cretaceous epoch/series. Its approximate time range is 112.0 ± 1.0 Ma to 99.6 ± 0.9 Ma...
stages
Faunal stage
In chronostratigraphy, a stage is a succession of rock strata laid down in a single age on the geologic timescale, which usually represents millions of years of deposition. A given stage of rock and the corresponding age of time will by convention have the same name, and the same boundaries.Rock...
of the early Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
. It is known from part of an upper forearm (humerus
Humerus
The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow....
), and some back bones (vertebrae).