Othnielia
Encyclopedia
Othnielia is a genus
of ornithischian dinosaur
, named after its original describer, Professor
Othniel Charles Marsh
, an American
paleontologist of the 19th century. The taxon
, Othnielia rex, was named by Peter Galton
in 1977 from a species Marsh (1877) called Nanosaurus rex.
Remains assigned to Othnielia have been found in Wyoming
, Utah
, and Colorado
in rocks of the Late Jurassic
age (Oxfordian
-Tithonian
) Morrison Formation
, but with Galton's 2007 revision of Morrison ornithischia
ns, the only definite remains are YPM 1875 (the holotype
femur
of "Nanosaurus
" 'rex') and possibly some other associated postcrania
l bits. He considered the femur undiagnostic and thus Othnielia to be a dubious name, and removed two partial skeletons to the new genus Othnielosaurus. It remains to be seen if this will be widely accepted, but this sort of taxonomic decision has much precedent (for example, Marasuchus
versus Lagosuchus
).
Without the remains now included in Othnielosaurus
, this animal is dubious
, and can only be described in generalities based on similar animals. It was relatively small for a dinosaur, at around 1.5 to 2 m (4.9 to 6.6 ft) long, and 10 kilograms (22 lb) in weight, and an agile biped
al herbivore
with proportionally small arms and long legs. Animals of this genus were included in the novel Jurassic Park as "othys", tree-climbing small herbivores, although there is no evidence for this kind of behavior.
.
reported a baby ornithopod
, possibly Othnielia rex from the Morrison Formation
at Garden Park, Colorado
. The specimen is speculated to be immature on the basis of its small bones, unfused neural arches, and the ends of its long bones are "spongy and incompletely formed." The specimen is catalogued as DMNH 21716. The skeleton was encased in five blocks of maroon sandstone. If the specimen is truly O. rex, it is about one third the size of a known adult specimen. However, the chronological age of the specimen could not be estimated because Othnielia eggs and hatchlings were unknown.
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 ornithischian 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...
, named after its original describer, Professor
Professor
A professor is a scholarly teacher; the precise meaning of the term varies by country. Literally, professor derives from Latin as a "person who professes" being usually an expert in arts or sciences; a teacher of high rank...
Othniel Charles Marsh
Othniel Charles Marsh
Othniel Charles Marsh was an American paleontologist. Marsh was one of the preeminent scientists in the field; the discovery or description of dozens of news species and theories on the origins of birds are among his legacies.Born into a modest family, Marsh was able to afford higher education...
, an American
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
paleontologist of the 19th century. The taxon
Taxon
|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...
, Othnielia rex, was named by Peter Galton
Peter Galton
Peter M. Galton is a British vertebrate paleontologist working in America, who has to date written or co-written about a hundred papers in scientific journals or chapters in paleontology textbooks, especially on ornithischian and prosauropod dinosaurs.With Robert Bakker in a joint article...
in 1977 from a species Marsh (1877) called Nanosaurus rex.
Remains assigned to Othnielia have been found in Wyoming
Wyoming
Wyoming is a state in the mountain region of the Western United States. The western two thirds of the state is covered mostly with the mountain ranges and rangelands in the foothills of the Eastern Rocky Mountains, while the eastern third of the state is high elevation prairie known as the High...
, Utah
Utah
Utah is a state in the Western United States. It was the 45th state to join the Union, on January 4, 1896. Approximately 80% of Utah's 2,763,885 people live along the Wasatch Front, centering on Salt Lake City. This leaves vast expanses of the state nearly uninhabited, making the population the...
, and 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...
in rocks of the Late Jurassic
Late Jurassic
The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 161.2 ± 4.0 to 145.5 ± 4.0 million years ago , which is preserved in Upper Jurassic strata. In European lithostratigraphy, the name "Malm" indicates rocks of Late Jurassic age...
age (Oxfordian
Oxfordian stage
The Oxfordian is, in the ICS' geologic timescale, the earliest age of the Late Jurassic epoch, or the lowest stage of the Upper Jurassic series. It spans the time between 161.2 ± 4 Ma and 155.7 ± 4 Ma...
-Tithonian
Tithonian
In the geologic timescale the Tithonian is the latest age of the Late Jurassic epoch or the uppermost stage of the Upper Jurassic series. It spans the time between 150.8 ± 4 Ma and 145.5 ± 4 Ma...
) Morrison Formation
Morrison Formation
The Morrison Formation is a distinctive sequence of Late Jurassic sedimentary rock that is found in the western United States, which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandstone, siltstone and limestone and is light grey, greenish...
, but with Galton's 2007 revision of Morrison ornithischia
Ornithischia
Ornithischia or Predentata is an extinct order of beaked, herbivorous dinosaurs. The name ornithischia is derived from the Greek ornitheos meaning 'of a bird' and ischion meaning 'hip joint'...
ns, the only definite remains are YPM 1875 (the holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
femur
Femur
The femur , or thigh bone, is the most proximal bone of the leg in tetrapod vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs. In vertebrates with four legs such as dogs and horses, the femur is found only in...
of "Nanosaurus
Nanosaurus
Nanosaurus is the name given to a genus of dinosaur from the Late Jurassic. Described by Othniel Charles Marsh in 1877, it is a poorly-known ornithischian of uncertain affinities. Its fossils are known from the Morrison Formation of Colorado and possibly Wyoming...
" 'rex') and possibly some other associated postcrania
Postcrania
Postcrania[p] in zoology and vertebrate paleontology refers to all or part of the skeleton apart from the skull. Frequently, fossil remains, e.g...
l bits. He considered the femur undiagnostic and thus Othnielia to be a dubious name, and removed two partial skeletons to the new genus Othnielosaurus. It remains to be seen if this will be widely accepted, but this sort of taxonomic decision has much precedent (for example, Marasuchus
Marasuchus
Marasuchus is a genus of dinosaur-like ornithodiran from the middle Triassic Chañares Formation of Argentina. The species Marasuchus lilloensis was originally described as a second species of Lagosuchus, L. lilloensis...
versus Lagosuchus
Lagosuchus
Lagosuchus is a genus of small archosaur from the middle Triassic period. It is generally thought to be closely related to dinosaurs, as a member of the Dinosauromorpha...
).
Without the remains now included in Othnielosaurus
Othnielosaurus
Othnielosaurus is a genus of ornithischian dinosaur that lived about 155 to 148 million years ago, during the Late Jurassic-age Morrison Formation of the western United States. It is named in honor of famed paleontologist Othniel Charles Marsh, and was formerly assigned to the genus...
, this animal is dubious
Nomen dubium
In zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application...
, and can only be described in generalities based on similar animals. It was relatively small for a dinosaur, at around 1.5 to 2 m (4.9 to 6.6 ft) long, and 10 kilograms (22 lb) in weight, and an agile biped
Biped
Bipedalism is a form of terrestrial locomotion where an organism moves by means of its two rear limbs, or legs. An animal or machine that usually moves in a bipedal manner is known as a biped , meaning "two feet"...
al herbivore
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
with proportionally small arms and long legs. Animals of this genus were included in the novel Jurassic Park as "othys", tree-climbing small herbivores, although there is no evidence for this kind of behavior.
Referred specimens
Only the original holotype of Othnielia and two partial skeletons were specifically dealt with in Galton's paper, leaving unsettled the assignment of several other specimens that have appeared in the literature. Included among these are a nearly complete specimen in the Aathal Museum nicknamed "Barbara", and a dentary (MWC 5822, again referred to O. rex). Skeletons identified as Othnielia are also on display at the Denver Museum of Nature and ScienceDenver Museum of Nature and Science
The Denver Museum of Nature & Science is a municipal natural history and science museum in Denver, Colorado. It is a resource for informal science education in the Rocky Mountain region. A variety of exhibitions, programs, and activities help museum visitors learn about the natural history of...
.
DMNH 21716
Kathleen Brill and Kenneth CarpenterKenneth Carpenter
Kenneth Carpenter is a paleontologist. He is the museum director of the USU Eastern Prehistoric Museum and author or co-author of a number of books on dinosaurs and Mesozoic life...
reported a baby ornithopod
Ornithopod
Ornithopods or members of the clade Ornithopoda are a group of ornithischian dinosaurs that started out as small, bipedal running grazers, and grew in size and numbers until they became one of the most successful groups of herbivores in the Cretaceous world, and dominated the North American...
, possibly Othnielia rex from the Morrison Formation
Morrison Formation
The Morrison Formation is a distinctive sequence of Late Jurassic sedimentary rock that is found in the western United States, which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandstone, siltstone and limestone and is light grey, greenish...
at Garden Park, Colorado
Garden Park, Colorado
Garden Park, in southcentral Colorado, is known for its Jurassic dinosaurs and the role the specimens played in the infamous bone wars of the late 19th century. Located north of Cañon City, Colorado, the name originates from the area providing vegetables to the miners at nearby Cripple Creek in...
. The specimen is speculated to be immature on the basis of its small bones, unfused neural arches, and the ends of its long bones are "spongy and incompletely formed." The specimen is catalogued as DMNH 21716. The skeleton was encased in five blocks of maroon sandstone. If the specimen is truly O. rex, it is about one third the size of a known adult specimen. However, the chronological age of the specimen could not be estimated because Othnielia eggs and hatchlings were unknown.
External links
- Othnielia on Thescelosaurus!