Ornithomimus
Encyclopedia
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. Most of these have subsequently been assigned to new genera or shown to be not directly related to Ornithomimus. The best material of species still considered part of the genus has been found in Canada, representing the earlier Edmontonian-age Ornithomimus edmontonicus Sternberg 1933, known from several skeletons. However, on some of these the new genus Dromiceiomimus including Dromiceiomimus brevitertius (Parks 1926) has been based, causing taxonomic problems of priority and identity that are still unresolved.
Ornithomimus was a relatively small swift bipedal animal, equipped with a small toothless beaked head, that may indicate an omnivorous diet.
Like other ornithomimids, Ornithomimus is characterized by a foot with three weight-bearing toes, long slender arms and a long neck with a birdlike, elongated, toothless, beaked skull. It was biped
al and superficially resembled an ostrich
, except for its long tail. It would have been a swift runner. It had very long limbs, hollow bones, and a large brain and eyes. The brains of ornithomimids were large for dinosaurs, but this may not necessarily be a sign of greater intelligence; some paleontologists think that the enlarged portions of the brain were dedicated to kinesthetic coordination. Their hands are remarkably sloth-like in appearance, which led Henry Fairfield Osborn
to suggest that they were used to hook branches during feeding.
Ornithomimus differs from other ornithomimids, such as Struthiomimus
, in having a short back, long slender forearms, very slender, straight hand and foot claws and in having metacarpals and fingers of similar lengths.
The three Ornithomimus species today seen as possibly valid, differ rather in size. In 2010 Gregory S. Paul
estimated the length of O. edmontonicus at 3.8 metres, its weight at 170 kilograms (374.8 lb). One of its specimens, CMN 12228, preserves a femur
(thigh bone) 46.8 centimetres (18.4 in) long. O. sedens was by Paul estimated at 4.8 metres and 350 kilograms (771.6 lb). O. velox, the type species
of Ornithomimus, is based on material of a much smaller animal. Whereas the holotype
of O. edmontonicus, CMN 8632, preserves a second metacarpal eighty-four millimetres long, the same element with O. velox measures only fifty-three millimetres.
, Ornithomimus velox, was first named by O.C. Marsh in 1890, based on syntype
s YPM 542 and YPM 548, a partial hindlimb and forelimb found on 30 June 1889 by George Lyman Cannon in the Denver Formation
of Colorado
. The generic name means "bird mimic", derived from Greek ὄρνις, ornis, "bird", and μῖμος, mimos, "mimic", in reference to the bird-like foot. The specific name means "swift" in Latin
. Simultaneously, Marsh named two other species: Ornithomimus tenuis, based on specimen USNM 5814, and Ornithomimus grandis. Both consist of fragmentary fossils found by John Bell Hatcher
in Montana
of which it is today understood they represent tyrannosauroid material. At first Marsh assumed Ornithomimus was a ornithopod
but this changed when Hatcher found specimen USNM 4736, a partial ornithomimid skeleton, in Wyoming
, which Marsh named Ornithomimus sedens in 1892. On that occasion also Ornithomimus minutus was created based on specimen YPM 1049, a metatarsus
, since recognized as belonging to the Alvarezsauridae
.
A sixth species, Ornithomimus altus, was named in 1902 by Lawrence Lambe
, based on specimen CMN 930, hindlimbs found in 1901 in Alberta
, but this was in 1916 renamed to a separate genus, Struthiomimus
, by Henry Fairfield Osborn
. In 1920 Charles Whitney Gilmore named Ornithomimus affinis for Dryosaurus grandis Lull 1911, based on indeterminate material. In 1930 Loris Russell renamed Struthiomimus brevetertius Parks 1926 and Struthiomimus samueli Parks 1928 into Ornithomimus brevitertius and Ornithomimus samueli. The same year Oliver Perry Hay
renamed Aublysodon mirandus Leidy 1868 into Ornithomimus mirandus, today seen as a nomen dubium
. In 1933 William Arthur Parks created a Ornithomimus elegans, today seen as either belonging to Chirostenotes
or Elmisaurus
. That same year, Gilmore named Ornithomimus asiaticus for material found in Inner Mongolia
.
Also in 1933, Charles Mortram Sternberg
named the species Ornithomimus edmontonicus for a nearly complete skeleton from the Horseshoe Canyon Formation
of Alberta
, specimen CMN 8632.
At first it had been common to name each newly discovered ornithomimid as a species of Ornithomimus. In the sixties, this tendency was still strong as is shown by the fact that Oskar Kuhn
renamed Megalosaurus lonzeensis Dollo 1903 from Belgium
into Ornithomimus lonzeensis (today understood to be a abelisauroid claw), and Dale Rusell in 1967 renamed Struthiomimus currellii Parks 1933 and Struthiomimus ingens Parks 1933 into Ornithomimus currellii and Ornithomimus ingens. At the same time it was usual that workers referred to the entire ornithomimid material as simply "Struthiomimus". To solve this confusion by scientifically testing the separation between Ornithomimus and Struthiomimus, in 1972 Dale Russell published a morphometric study showing that statistical differences in some proportions could be used to distinguish the two. He concluded that Struthiomimus and Ornithomimus were valid genera. In the latter Russell recognised two species: the type species Ornithomimus velox and Ornithomimus edmontonicus even though he had trouble reliably distinguishing it from O. velox. Struthiomimus currellii he considered a younger synomym of Ornithomimus edmontonicus. However, Russell also interpreted the data as indicating that many specimens could not be referred to either Ornithomimus or Struthiomimus. Therefore he created two new genera. The first was Archaeornithomimus
to which Ornithomimus asiaticus and Ornithomimus affinis were assigned, becoming an Archaeornithomimus asiaticus and an Archaeornithomimus affinis. The second genus was Dromiceiomimus, meaning "Emu
mimic" from the old generic name for the emu, Dromiceius. Russell assigned several former Ornithomimus species named during the 20th century, including O. brevitertius and O. ingens, to the new genus as Dromiceimimus brevitertius. He renamed Ornithomimus samueli into a second Dromiceiomimus species: Dromiceiomimus samueli.
e from the Navesink Formation
of New Jersey
belonging to divers material named Coelosaurus antiquus ("antique hollow lizard") by Joseph Leidy
in 1865. The tibiae were first attributed to Ornithomimus in 1979 by Donald Baird and John R. Horner as Ornithomimus antiquus. Normally, this would have made Ornithomimus a junior synonym of Coelosaurus, but Baird and Horner discovered that the name "Coelosaurus" was preoccupied by a dubious
taxon based on a single vertebra, named Coelosaurus by an anonymous author now known to be Richard Owen
in 1854. Baird referred several other specimens from New Jersey and Maryland
to O. antiquus. Beginning in 1997, Robert Sullivan
regarded O. velox and O. edmontonicus as junior synonyms of O. antiquus. Like Russell, he considered the former two species indistinguishable from each other, and noted that they both shared distinctive features with O. antiquus. However, David Weishampel (2004) considered "C." antiquus to be indeterminate among ornithomimosaurs, and therefore a nomen dubium
.
In 1988 Gregory S. Paul
renamed Gallimimus
bullatus into Ornithomimus bullatus. This has found no acceptance among other workers and presently the name is not used by Paul himself.
studied Russell's 1972 proportional statistics to re-analyze ornithomimid relationships in light of new specimens. They concluded that there was no justification to separate Dromiceiomimus from Ornithomimus, noting that Dromiceiomimus must therefore be considered a synonym of O. edmontonicus. However, they did not include the type species of Ornithomimus, O. velox, in this analysis. The same team further supported the synonymy between Dromiceiomimus and O. edmontonicus in a 2006 lecture at the Society of Vertebrate Paleontology
annual meeting, and their opinion was further supported in a paper by Nicholas Longrich in 2008. Makovicky's team also considered Dromiceiomimus samueli to be a junior synonym of O. edmontonicus, though Longrich suggested it may belong to a distinct species also represented by Ornithomimus remains from the Dinosaur Park Formation
which have yet to be described.
Apart from O. edmontonicus dating to the early Maastrichtian
, two other species are presently considered to be possibly valid, both from the late Maastrichtian. O. sedens was named by Marsh in 1891 from partial remains found in the Lance Formation
of Wyoming
, only one year after the description of O. velox. Dale Russell, in his 1972 revision of ornithomimids, could not determine which genus it actually belonged to, though he speculated that it may be intermediate between Struthiomimus and Dromiceiomimus. In 1985 he considered it a species of Ornithomimus. It has since been referred to mainly as Struthiomimus sedens, based on complete specimens from Montana
(as well as some fragments from Alberta and Saskatchewan
), though these yet have to be described and compared to the O. sedens holotype.
The other is the original type species: O. velox, at first known from very limited remains. Additional specimens referred to O. velox have been described from the Denver Formation and from the Ferris Formation
of Wyoming
. One specimen attributed to O. velox from the Kaiparowitz Formation of Utah
, was described in 1985. Re-evaluation of this specimen by Lindsay Zanno and colleagues in 2010, however, cast doubt on its assignment to O. velox, and possibly even to Ornithomimus.
Ornithomimus had legs that seem clearly suited for rapid locomotion, with the tibia
about 20% longer than the femur
. The large eye sockets suggest a keen visual sense, and also suggest the possibility that they were nocturnal.
In a 2001 study conducted by Bruce Rothschild and other paleontologists, 178 foot bones referred to Ornithomimus 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 ornithomimid 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...
Period of what is now North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
.
In 1890 Ornithomimus velox was named 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...
on the basis of a foot and partial hand from the 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...
Denver Formation
Denver Formation
The Denver Formation is a geological formation in Colorado whose strata date back to the Late Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation.-Ornithischians:-Saurischians:-References:...
. Another seventeen species have been named since. Most of these have subsequently been assigned to new genera or shown to be not directly related to Ornithomimus. The best material of species still considered part of the genus has been found in Canada, representing the earlier Edmontonian-age Ornithomimus edmontonicus Sternberg 1933, known from several skeletons. However, on some of these the new genus Dromiceiomimus including Dromiceiomimus brevitertius (Parks 1926) has been based, causing taxonomic problems of priority and identity that are still unresolved.
Ornithomimus was a relatively small swift bipedal animal, equipped with a small toothless beaked head, that may indicate an omnivorous diet.
Description
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 and superficially resembled an ostrich
Ostrich
The Ostrich is one or two species of large flightless birds native to Africa, the only living member of the genus Struthio. Some analyses indicate that the Somali Ostrich may be better considered a full species apart from the Common Ostrich, but most taxonomists consider it to be a...
, except for its long tail. It would have been a swift runner. It had very long limbs, hollow bones, and a large brain and eyes. The brains of ornithomimids were large for dinosaurs, but this may not necessarily be a sign of greater intelligence; some paleontologists think that the enlarged portions of the brain were dedicated to kinesthetic coordination. Their hands are remarkably sloth-like in appearance, which led Henry Fairfield Osborn
Henry Fairfield Osborn
Henry Fairfield Osborn, Sr. ForMemRS was an American geologist, paleontologist, and eugenicist.-Early life and career:...
to suggest that they were used to hook branches during feeding.
Ornithomimus differs from other ornithomimids, such as Struthiomimus
Struthiomimus
Struthiomimus is a genus of ornithomimid dinosaur from the late Cretaceous of Alberta, Canada. It was a long-legged, ostrich-like dinosaur.The bipedal Struthiomimus stood about long and tall at the hips and weighed around...
, in having a short back, long slender forearms, very slender, straight hand and foot claws and in having metacarpals and fingers of similar lengths.
The three Ornithomimus species today seen as possibly valid, differ rather in size. In 2010 Gregory S. Paul
Gregory S. Paul
Gregory Scott Paul is a freelance researcher, author and illustrator who works in paleontology, and more recently has examined sociology and theology. He is best known for his work and research on theropod dinosaurs and his detailed illustrations, both live and skeletal...
estimated the length of O. edmontonicus at 3.8 metres, its weight at 170 kilograms (374.8 lb). One of its specimens, CMN 12228, preserves a 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...
(thigh bone) 46.8 centimetres (18.4 in) long. O. sedens was by Paul estimated at 4.8 metres and 350 kilograms (771.6 lb). O. velox, 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 Ornithomimus, is based on material of a much smaller animal. Whereas 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...
of O. edmontonicus, CMN 8632, preserves a second metacarpal eighty-four millimetres long, the same element with O. velox measures only fifty-three millimetres.
First species named
The history of Ornithomimus classification, and the classification of ornithomimids in general, has been complicated. The type speciesType 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...
, Ornithomimus velox, was first named by O.C. Marsh in 1890, based on syntype
Syntype
In biological nomenclature, a syntype is a term used to indicate a specimen with a special status.In zoological nomenclature, a syntype is defined as "Each specimen of a type series from which neither a holotype nor a lectotype has been designated [Arts. 72.1.2, 73.2, 74]. The syntypes...
s YPM 542 and YPM 548, a partial hindlimb and forelimb found on 30 June 1889 by George Lyman Cannon in the Denver Formation
Denver Formation
The Denver Formation is a geological formation in Colorado whose strata date back to the Late Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation.-Ornithischians:-Saurischians:-References:...
of 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...
. The generic name means "bird mimic", derived from Greek ὄρνις, ornis, "bird", and μῖμος, mimos, "mimic", in reference to the bird-like foot. The specific name means "swift" in Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
. Simultaneously, Marsh named two other species: Ornithomimus tenuis, based on specimen USNM 5814, and Ornithomimus grandis. Both consist of fragmentary fossils found by John Bell Hatcher
John Bell Hatcher
John Bell Hatcher was an American paleontologist and fossil hunter best known for discovering Torosaurus.-Biography:...
in Montana
Montana
Montana is a state in the Western United States. The western third of Montana contains numerous mountain ranges. Smaller, "island ranges" are found in the central third of the state, for a total of 77 named ranges of the Rocky Mountains. This geographical fact is reflected in the state's name,...
of which it is today understood they represent tyrannosauroid material. At first Marsh assumed Ornithomimus was a 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...
but this changed when Hatcher found specimen USNM 4736, a partial ornithomimid skeleton, 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...
, which Marsh named Ornithomimus sedens in 1892. On that occasion also Ornithomimus minutus was created based on specimen YPM 1049, a metatarsus
Metatarsus
The metatarsus or metatarsal bones are a group of five long bones in the foot located between the tarsal bones of the hind- and mid-foot and the phalanges of the toes. Lacking individual names, the metatarsal bones are numbered from the medial side : the first, second, third, fourth, and fifth...
, since recognized as belonging to the Alvarezsauridae
Alvarezsauridae
Alvarezsauridae is an enigmatic family of small, long-legged running dinosaurs. Although originally thought to represent the earliest known flightless birds, a consensus of recent work suggests that they are primitive members of the Maniraptora. Other work found them to be the sister group to the...
.
A sixth species, Ornithomimus altus, was named in 1902 by Lawrence Lambe
Lawrence Lambe
Lawrence Morris Lambe was a Canadian geologist and palaeontologist from the Geological Survey of Canada .His published work, describing the diverse and plentiful dinosaur discoveries from the fossil beds in Alberta, did much to bring dinosaurs into the public eye and helped usher in the Golden...
, based on specimen CMN 930, hindlimbs found in 1901 in Alberta
Alberta
Alberta is a province of Canada. It had an estimated population of 3.7 million in 2010 making it the most populous of Canada's three prairie provinces...
, but this was in 1916 renamed to a separate genus, Struthiomimus
Struthiomimus
Struthiomimus is a genus of ornithomimid dinosaur from the late Cretaceous of Alberta, Canada. It was a long-legged, ostrich-like dinosaur.The bipedal Struthiomimus stood about long and tall at the hips and weighed around...
, by Henry Fairfield Osborn
Henry Fairfield Osborn
Henry Fairfield Osborn, Sr. ForMemRS was an American geologist, paleontologist, and eugenicist.-Early life and career:...
. In 1920 Charles Whitney Gilmore named Ornithomimus affinis for Dryosaurus grandis Lull 1911, based on indeterminate material. In 1930 Loris Russell renamed Struthiomimus brevetertius Parks 1926 and Struthiomimus samueli Parks 1928 into Ornithomimus brevitertius and Ornithomimus samueli. The same year Oliver Perry Hay
Oliver Perry Hay
Oliver Perry Hay was an American professor, herpetologist, ichthyologist, and paleontologist. From 1894-1895 he worked at the Field Museum of Natural History as Assistant Curator of Zoology where, despite his specialty in ichthyology, he worked in all non-ornithological fields of zoology...
renamed Aublysodon mirandus Leidy 1868 into Ornithomimus mirandus, today seen as a nomen dubium
Nomen dubium
In zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application...
. In 1933 William Arthur Parks created a Ornithomimus elegans, today seen as either belonging to Chirostenotes
Chirostenotes
Chirostenotes is a genus of oviraptorosaurian dinosaur from the late Cretaceous of Alberta, Canada. The type species is Chirostenotes pergracilis. Some researchers recognize a second species, C...
or Elmisaurus
Elmisaurus
Elmisaurus is an extinct genus of dinosaur from the Late Cretaceous. It was a theropod belonging to the Oviraptorosauria. Its fossils have been found in Asia and North America. It is known from only its feet and hands....
. That same year, Gilmore named Ornithomimus asiaticus for material found in 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...
.
Also in 1933, Charles Mortram Sternberg
Charles Mortram Sternberg
Charles M. Sternberg was an American-Canadian fossil collector and paleontologist, son of Charles Hazelius Sternberg.Late in his career, he collected and described Pachyrhinosaurus, Brachylophosaurus, Parksosaurus and Edmontonia...
named the species Ornithomimus edmontonicus for a nearly complete skeleton from the Horseshoe Canyon Formation
Horseshoe Canyon Formation
The Horseshoe Canyon Formation is part of the Edmonton Group and is up to 230m in thickness. It is Late Campanian to Early Maastrichtian in age and is composed of mudstone, sandstone, and carbonaceous shales...
of Alberta
Alberta
Alberta is a province of Canada. It had an estimated population of 3.7 million in 2010 making it the most populous of Canada's three prairie provinces...
, specimen CMN 8632.
Reclassification by Dale Russell
Oskar Kuhn
Oskar Kuhn was a German palaeontologist.-Life and career:Kuhn was educated in Dinkelsbühl and Bamberg and then studied natural science, specialising in geology and paleontology, at the University of Munich, from which he received his D. Phil...
renamed Megalosaurus lonzeensis Dollo 1903 from Belgium
Belgium
Belgium , officially the Kingdom of Belgium, is a federal state in Western Europe. It is a founding member of the European Union and hosts the EU's headquarters, and those of several other major international organisations such as NATO.Belgium is also a member of, or affiliated to, many...
into Ornithomimus lonzeensis (today understood to be a abelisauroid claw), and Dale Rusell in 1967 renamed Struthiomimus currellii Parks 1933 and Struthiomimus ingens Parks 1933 into Ornithomimus currellii and Ornithomimus ingens. At the same time it was usual that workers referred to the entire ornithomimid material as simply "Struthiomimus". To solve this confusion by scientifically testing the separation between Ornithomimus and Struthiomimus, in 1972 Dale Russell published a morphometric study showing that statistical differences in some proportions could be used to distinguish the two. He concluded that Struthiomimus and Ornithomimus were valid genera. In the latter Russell recognised two species: the type species Ornithomimus velox and Ornithomimus edmontonicus even though he had trouble reliably distinguishing it from O. velox. Struthiomimus currellii he considered a younger synomym of Ornithomimus edmontonicus. However, Russell also interpreted the data as indicating that many specimens could not be referred to either Ornithomimus or Struthiomimus. Therefore he created two new genera. The first was Archaeornithomimus
Archaeornithomimus
Archaeornithomimus is a genus of ornithomimosaurian theropod dinosaur from the Late Cretaceous of China, 70 million years ago....
to which Ornithomimus asiaticus and Ornithomimus affinis were assigned, becoming an Archaeornithomimus asiaticus and an Archaeornithomimus affinis. The second genus was Dromiceiomimus, meaning "Emu
Emu
The Emu Dromaius novaehollandiae) is the largest bird native to Australia and the only extant member of the genus Dromaius. It is the second-largest extant bird in the world by height, after its ratite relative, the ostrich. There are three subspecies of Emus in Australia...
mimic" from the old generic name for the emu, Dromiceius. Russell assigned several former Ornithomimus species named during the 20th century, including O. brevitertius and O. ingens, to the new genus as Dromiceimimus brevitertius. He renamed Ornithomimus samueli into a second Dromiceiomimus species: Dromiceiomimus samueli.
Final species named
The first Ornithomimus remains ever found may be two tibiaTibia
The tibia , shinbone, or shankbone is the larger and stronger of the two bones in the leg below the knee in vertebrates , and connects the knee with the ankle bones....
e from the Navesink Formation
Navesink Formation
The Navesink Formation is a 66 to 70 mya greensand glauconitic marl and sand geological formation in New Jersey. It is known for it its Cretaceous era fossil shell beds and dinosaur bones.-Description:...
of New Jersey
New Jersey
New Jersey is a state in the Northeastern and Middle Atlantic regions of the United States. , its population was 8,791,894. It is bordered on the north and east by the state of New York, on the southeast and south by the Atlantic Ocean, on the west by Pennsylvania and on the southwest by Delaware...
belonging to divers material named Coelosaurus antiquus ("antique hollow lizard") by Joseph Leidy
Joseph Leidy
Joseph Leidy was an American paleontologist.Leidy was professor of anatomy at the University of Pennsylvania, and later was a professor of natural history at Swarthmore College. His book Extinct Fauna of Dakota and Nebraska contained many species not previously described and many previously...
in 1865. The tibiae were first attributed to Ornithomimus in 1979 by Donald Baird and John R. Horner as Ornithomimus antiquus. Normally, this would have made Ornithomimus a junior synonym of Coelosaurus, but Baird and Horner discovered that the name "Coelosaurus" was preoccupied by a dubious
Nomen dubium
In zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application...
taxon based on a single vertebra, named Coelosaurus by an anonymous author now known to be Richard Owen
Richard Owen
Sir Richard Owen, FRS KCB was an English biologist, comparative anatomist and palaeontologist.Owen is probably best remembered today for coining the word Dinosauria and for his outspoken opposition to Charles Darwin's theory of evolution by natural selection...
in 1854. Baird referred several other specimens from New Jersey and 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...
to O. antiquus. Beginning in 1997, Robert Sullivan
Robert Sullivan
Robert Sullivan may refer to:*Robert Sullivan *Robert Baldwin Sullivan, Canadian lawyer, judge, and the second Mayor of Toronto*Robert J. Sullivan, Jr. , American politician...
regarded O. velox and O. edmontonicus as junior synonyms of O. antiquus. Like Russell, he considered the former two species indistinguishable from each other, and noted that they both shared distinctive features with O. antiquus. However, David Weishampel (2004) considered "C." antiquus to be indeterminate among ornithomimosaurs, and therefore a nomen dubium
Nomen dubium
In zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application...
.
In 1988 Gregory S. Paul
Gregory S. Paul
Gregory Scott Paul is a freelance researcher, author and illustrator who works in paleontology, and more recently has examined sociology and theology. He is best known for his work and research on theropod dinosaurs and his detailed illustrations, both live and skeletal...
renamed Gallimimus
Gallimimus
Gallimimus is a genus of ornithomimid theropod dinosaur from the late Cretaceous period Nemegt Formation of Mongolia. With individuals as long as , it was one of the largest ornithomimosaurs...
bullatus into Ornithomimus bullatus. This has found no acceptance among other workers and presently the name is not used by Paul himself.
Present interpretations
Even after Russell's study, various researchers have found reasons to lump some or all of these species back into Ornithomimus in various combinations. In 2004, Peter Makovicky, Yoshitsugu Kobayashi and Phil CurriePhil Currie
Philip John Currie, AOE is a Canadian palaeontologist and museum curator who helped found the Royal Tyrrell Museum of Palaeontology in Drumheller, Alberta and is now a professor at the University of Alberta in Edmonton...
studied Russell's 1972 proportional statistics to re-analyze ornithomimid relationships in light of new specimens. They concluded that there was no justification to separate Dromiceiomimus from Ornithomimus, noting that Dromiceiomimus must therefore be considered a synonym of O. edmontonicus. However, they did not include the type species of Ornithomimus, O. velox, in this analysis. The same team further supported the synonymy between Dromiceiomimus and O. edmontonicus in a 2006 lecture at the Society of Vertebrate Paleontology
Society of Vertebrate Paleontology
The Society of Vertebrate Paleontology was founded in 1940 for individuals with an interest in vertebrate paleontology. SVP now has almost 2,000 members. The society's website states that SVP "is organized exclusively for educational and scientific purposes...
annual meeting, and their opinion was further supported in a paper by Nicholas Longrich in 2008. Makovicky's team also considered Dromiceiomimus samueli to be a junior synonym of O. edmontonicus, though Longrich suggested it may belong to a distinct species also represented by Ornithomimus remains from the Dinosaur Park Formation
Dinosaur Park Formation
The Dinosaur Park Formation is the uppermost member of the Judith River Group, a major geologic unit in southern Alberta. It was laid down over a period of time between about 76.5 and 75 million years ago. The formation is made up of deposits of a high-sinuosity fluvial system, and is capped...
which have yet to be described.
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...
, two other species are presently considered to be possibly valid, both from the late Maastrichtian. O. sedens was named by Marsh in 1891 from partial remains found in the Lance Formation
Lance Formation
The Lance Formation is a division of Late Cretaceous rocks in the western United States. Named after Lance Creek, Wyoming, the microvertebrate fossils and dinosaurs represent important components of the latest Mesozoic vertebrate faunas...
of 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...
, only one year after the description of O. velox. Dale Russell, in his 1972 revision of ornithomimids, could not determine which genus it actually belonged to, though he speculated that it may be intermediate between Struthiomimus and Dromiceiomimus. In 1985 he considered it a species of Ornithomimus. It has since been referred to mainly as Struthiomimus sedens, based on complete specimens from Montana
Montana
Montana is a state in the Western United States. The western third of Montana contains numerous mountain ranges. Smaller, "island ranges" are found in the central third of the state, for a total of 77 named ranges of the Rocky Mountains. This geographical fact is reflected in the state's name,...
(as well as some fragments from Alberta and Saskatchewan
Saskatchewan
Saskatchewan is a prairie province in Canada, which has an area of . Saskatchewan is bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, and on the south by the U.S. states of Montana and North Dakota....
), though these yet have to be described and compared to the O. sedens holotype.
The other is the original type species: O. velox, at first known from very limited remains. Additional specimens referred to O. velox have been described from the Denver Formation and from the Ferris Formation
Ferris Formation
The Ferris Formation is a Late Cretaceous to Paleocene , fluvial-deltaic geological formation in southern Wyoming. It contains a variety of trace and body fossils, preserved in sandy fluvial channel deposits and overbank units...
of 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...
. One specimen attributed to O. velox from the Kaiparowitz Formation of 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...
, was described in 1985. Re-evaluation of this specimen by Lindsay Zanno and colleagues in 2010, however, cast doubt on its assignment to O. velox, and possibly even to Ornithomimus.
Phylogeny
In 1890 Marsh assigned Ornithomimus to the Ornithomimidae, a classification that is still common. Modern cladistic studies indicate a derived position in the ornithomimids; these however have only included O. edmontonicus in their analyses. The relationships between O. edmontonicus, O. velox and O. sedens have not been published.Paleobiology
The diet of Ornithomimus is still debated. As theropods, ornithomimids might have been carnivorous but their body shape would also have been suited for a partly or largely herbivorous lifestyle. Suggested food includes insects, crustaceans, fruit, leaves, branches, eggs, and the meat of lizards and small mammals.Ornithomimus had legs that seem clearly suited for rapid locomotion, with the tibia
Tibia
The tibia , shinbone, or shankbone is the larger and stronger of the two bones in the leg below the knee in vertebrates , and connects the knee with the ankle bones....
about 20% longer than the 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...
. The large eye sockets suggest a keen visual sense, and also suggest the possibility that they were nocturnal.
In a 2001 study conducted by Bruce Rothschild and other paleontologists, 178 foot bones referred to Ornithomimus 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
- Ornithomimus in The Dinosaur Encyclopaedia at Dino Russ' Lair