Archaeornithomimus
Encyclopedia
Archaeornithomimus is a genus
of ornithomimosaurian
theropod dinosaur
from the Late Cretaceous
of China
, 70 million years ago.
In 1923, during the American Museum of Natural History
expedition by Roy Chapman Andrews
to Inner Mongolia
, Peter Kaisen discovered numerous theropod remains in three quarries. These were named and shortly described by Charles Whitney Gilmore in 1933 as a new species of Ornithomimus
: Ornithomimus asiaticus. The specific name refers to the Asian provenance. The species was placed in the new genus Archaeornithomimus by Dale Russell
in 1972, making Archaeornithomimus asiaticus the type species
of the genus. The generic name combines that of Ornithomimus with a Greek ἀρχαῖος (archaios), "ancient", because Russell mistakenly believed that the layers Archaeornithomimus was found in dated to the Cenomanian
-Turonian
, about 95 million years old, making it one of the oldest ornithomimids known at the time. Gilmore had not assigned a holotype
specimen; in 1990 David Smith
and Peter Galton
in the first comprehensive description of the fossils, choose specimen AMNH 6565, a foot, as the lectotype
.
The fossils were found in the Iren Dabasu Formation
, which is presently seen as dating to the Campanian
-Maastrichtian
. They consist of the largely disarticulated remains of several individuals. Material of the skull and the lower jaws is lacking.
Foot bones found in the Early Cretaceous
Arundel Formation
of Maryland
had been referred by Othniel Charles Marsh
to Allosaurus
medius. In 1911 Richard Swann Lull named these as a new species of Dryosaurus
: Dryosaurus grandis. In 1920 Gilmore renamed them to a new species of Ornithomimus. As a Ornithomimus grandis already existed however, he coined the new species name Ornithomimus affinis. In 1972 Russell, despite the fact that the correct new combination should have been A. grandis, renamed them a second species of Archaeornithomimus: Archaeornithomimus affinis. In 1990 Smith and Galton concluded the remains were not ornithomimosaurian and came from some other small theropod.
In 1995 a third species of Archaeornithomimus was named by Lev Nesov: Archaeornithomimus bissektensis, based on holotype N 479/12457, a thighbone of a juvenile, found in the Bissekty Formation
of Uzbekistan
, dating to the Turonian
-Coniacian
. Today the affinity with Archaeornithomimus asiaticus is generally doubted.
Archaeornithomimus asiaticus was about 3.3 meters (11 ft) long, and weighed up to 50 kilograms (110 lb). The hindlimbs were robustly built. The third metatarsal was not pinched at the upper end, so the foot was not arctometatarsalian. Like other members of the ornithomimids, Archaeornithomimus was perhaps an omnivore
, eating everything from small mammals, to plants and fruit, to eggs, and even hatchlings of other Asian dinosaurs.
Russell assigned Archaeornithomimus to the Ornithomimidae. Recent cladistic analyses either confirm this or recover the species outside of the Ornithomimidae, basal in the Ornithomimosauria
.
In a 2001 study conducted by Bruce Rothschild and other paleontologists, 229 foot bones referred to Archaeornithomimus were examined for signs of stress fracture
, but none were found.
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 ornithomimosaurian
Ornithomimosauria
The Ornithomimosauria, ornithomimosaurs or ostrich dinosaurs were theropod dinosaurs which bore a superficial resemblance to modern ostriches. They were fast, omnivorous or herbivorous dinosaurs from the Cretaceous Period of Laurasia...
theropod 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...
from the Late 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...
of China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
, 70 million years ago.
In 1923, during the American Museum of Natural History
American Museum of Natural History
The American Museum of Natural History , located on the Upper West Side of Manhattan in New York City, United States, is one of the largest and most celebrated museums in the world...
expedition by Roy Chapman Andrews
Roy Chapman Andrews
Roy Chapman Andrews was an American explorer, adventurer and naturalist who became the director of the American Museum of Natural History. He is primarily known for leading a series of expeditions through the fragmented China of the early 20th century into the Gobi Desert and Mongolia...
to Inner Mongolia
Inner Mongolia
Inner Mongolia is an autonomous region of the People's Republic of China, located in the northern region of the country. Inner Mongolia shares an international border with the countries of Mongolia and the Russian Federation...
, Peter Kaisen discovered numerous theropod remains in three quarries. These were named and shortly described by Charles Whitney Gilmore in 1933 as a new species of Ornithomimus
Ornithomimus
Ornithomimus is a genus of ornithomimid dinosaur from the Late Cretaceous Period of what is now North America.In 1890 Ornithomimus velox was named by Othniel Charles Marsh on the basis of a foot and partial hand from the Maastrichtian Denver Formation. Another seventeen species have been named since...
: Ornithomimus asiaticus. The specific name refers to the Asian provenance. The species was placed in the new genus Archaeornithomimus by Dale Russell
Dale Russell
Dale A. Russell is a Canadian geologist/palaeontologist, currently Research Professor at The Department of Marine Earth and Atmospheric Sciences of North Carolina State University...
in 1972, making Archaeornithomimus asiaticus the type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
of the genus. The generic name combines that of Ornithomimus with a Greek ἀρχαῖος (archaios), "ancient", because Russell mistakenly believed that the layers Archaeornithomimus was found in dated to the Cenomanian
Cenomanian
The Cenomanian is, in the ICS' geological timescale the oldest or earliest age of the Late Cretaceous epoch or the lowest stage of the Upper Cretaceous series. An age is a unit of geochronology: it is a unit of time; the stage is a unit in the stratigraphic column deposited during the corresponding...
-Turonian
Turonian
The Turonian is, in the ICS' geologic timescale, the second age in the Late Cretaceous epoch, or a stage in the Upper Cretaceous series. It spans the time between 93.5 ± 0.8 Ma and 89.3 ± 1 Ma...
, about 95 million years old, making it one of the oldest ornithomimids known at the time. Gilmore had not assigned a 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...
specimen; in 1990 David Smith
David Smith
-In sports:* Dai Smith , rugby league footballer of the 1900s, who played for Salford, and Other Nationalities* David Smith , South African Olympic sport shooter...
and 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 the first comprehensive description of the fossils, choose specimen AMNH 6565, a foot, as the lectotype
Lectotype
In botanical nomenclature and zoological nomenclature, a lectotype is a kind of name-bearing type. When a species was originally described on the basis of a name-bearing type consisting of multiple specimens, one of those may be designated as the lectotype...
.
The fossils were found in the Iren Dabasu Formation
Iren Dabasu Formation
The Iren Dabasu Formation is a Mesozoic geologic formation. Dinosaur remains diagnostic to the genus level are among the fossils that have been recovered from the formation.-Ornithischians:-Saurischians:-References:...
, which is presently seen as dating to the Campanian
Campanian
The Campanian is, in the ICS' geologic timescale, the fifth of six ages of the Late Cretaceous epoch . The Campanian spans the time from 83.5 ± 0.7 Ma to 70.6 ± 0.6 Ma ...
-Maastrichtian
Maastrichtian
The Maastrichtian is, in the ICS' geologic timescale, the latest age or upper stage of the Late Cretaceous epoch or Upper Cretaceous series, the Cretaceous period or system, and of the Mesozoic era or erathem. It spanned from 70.6 ± 0.6 Ma to 65.5 ± 0.3 Ma...
. They consist of the largely disarticulated remains of several individuals. Material of the skull and the lower jaws is lacking.
Foot bones found in the Early Cretaceous
Early Cretaceous
The Early Cretaceous or the Lower Cretaceous , is the earlier or lower of the two major divisions of the Cretaceous...
Arundel Formation
Arundel Formation
The Arundel Formation, also known as the Arundel Clay, is a clay-rich sedimentary rock formation, within the Potomac Group, found in Maryland of the United States of America. It is of Aptian age . This rock unit had been economically important as a source of iron ore, but is now more notable for...
of Maryland
Maryland
Maryland is a U.S. state located in the Mid Atlantic region of the United States, bordering Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware to its east...
had been referred by 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...
to Allosaurus
Allosaurus
Allosaurus is a genus of large theropod dinosaur that lived 155 to 150 million years ago during the late Jurassic period . The name Allosaurus means "different lizard". It is derived from the Greek /allos and /sauros...
medius. In 1911 Richard Swann Lull named these as a new species of Dryosaurus
Dryosaurus
Dryosaurus is a genus of an ornithopod dinosaur that lived in the Late Jurassic period. It was an iguanodont . Fossils have been found in the western United States, and were first discovered in the late 19th century...
: Dryosaurus grandis. In 1920 Gilmore renamed them to a new species of Ornithomimus. As a Ornithomimus grandis already existed however, he coined the new species name Ornithomimus affinis. In 1972 Russell, despite the fact that the correct new combination should have been A. grandis, renamed them a second species of Archaeornithomimus: Archaeornithomimus affinis. In 1990 Smith and Galton concluded the remains were not ornithomimosaurian and came from some other small theropod.
In 1995 a third species of Archaeornithomimus was named by Lev Nesov: Archaeornithomimus bissektensis, based on holotype N 479/12457, a thighbone of a juvenile, found in the Bissekty Formation
Bissekty Formation
The Bissekty Formation is situated in the Kyzyl Kum desert of Uzbekistan, and dates from the late Cretaceous Period. Laid down in the early the Turonian to Coniacian stages, it is dated to about 90-85 ma .The Bissekty Formation is characterised by a mix of marine, brackish, freshwater, and...
of Uzbekistan
Uzbekistan
Uzbekistan , officially the Republic of Uzbekistan is a doubly landlocked country in Central Asia and one of the six independent Turkic states. It shares borders with Kazakhstan to the west and to the north, Kyrgyzstan and Tajikistan to the east, and Afghanistan and Turkmenistan to the south....
, dating to the Turonian
Turonian
The Turonian is, in the ICS' geologic timescale, the second age in the Late Cretaceous epoch, or a stage in the Upper Cretaceous series. It spans the time between 93.5 ± 0.8 Ma and 89.3 ± 1 Ma...
-Coniacian
Coniacian
The Coniacian is an age or stage in the geologic timescale. It is a subdivision of the Late Cretaceous epoch or Upper Cretaceous series and spans the time between 89.3 ± 1 Ma and 85.8 ± 0.7 Ma...
. Today the affinity with Archaeornithomimus asiaticus is generally doubted.
Archaeornithomimus asiaticus was about 3.3 meters (11 ft) long, and weighed up to 50 kilograms (110 lb). The hindlimbs were robustly built. The third metatarsal was not pinched at the upper end, so the foot was not arctometatarsalian. Like other members of the ornithomimids, Archaeornithomimus was perhaps an omnivore
Omnivore
Omnivores are species that eat both plants and animals as their primary food source...
, eating everything from small mammals, to plants and fruit, to eggs, and even hatchlings of other Asian dinosaurs.
Russell assigned Archaeornithomimus to the Ornithomimidae. Recent cladistic analyses either confirm this or recover the species outside of the Ornithomimidae, basal in the Ornithomimosauria
Ornithomimosauria
The Ornithomimosauria, ornithomimosaurs or ostrich dinosaurs were theropod dinosaurs which bore a superficial resemblance to modern ostriches. They were fast, omnivorous or herbivorous dinosaurs from the Cretaceous Period of Laurasia...
.
In a 2001 study conducted by Bruce Rothschild and other paleontologists, 229 foot bones referred to Archaeornithomimus were examined for signs of stress fracture
Stress fracture
A stress fracture is one type of incomplete fracture in bones. It is caused by "unusual or repeated stress" and also heavy continuous weight on the ankle or leg...
, but none were found.
External links
- Archaeornithomimus in The Dinosaur Encyclopaedia, at Dino Russ's Lair