First species named The history of
Ornithomimus classification and the classification of ornithomimids in general has been very complicated. The
type species,
Ornithomimus velox, was first named by
O.C. Marsh in 1890 and is based on
syntypes YPM 542 and YPM 548 (a partial hindlimb and forelimb, respectively), found by
George Lyman Cannon in the
Denver Formation of
Colorado on June 30,
1889. The generic name means "bird mimic", derived from Greek words 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, which is today understood as
tyrannosauroid material. At first, Marsh assumed
Ornithomimus was an
ornithopod, but this changed when Hatcher and A. E. Sullins found the specimen USNM 4736, a partial ornithomimid skeleton, in 1891 from the
Lance Formation of
Wyoming. Marsh named it
Ornithomimus sedens in
1892, though the specimen remained unnumbered and not figured until
Charles Whitney Gilmore's 1920 re-description. Marsh also named
Ornithomimus minutus was also created based on the specimen YPM 1049 (a
metatarsus) in 1892, but it has since been recognized as belonging to an
alvarezsaurid. A sixth species,
Ornithomimus altus, was named in
1902 by
Lawrence Lambe and was based on specimen CMN 930 (hindlimbs found in
1901 in
Alberta), but this was renamed to a separate genus in
1916:
Struthiomimus, by
Henry Fairfield Osborn. In
1920, Gilmore named
Ornithomimus affinis for
Dryosaurus grandis (Lull
1911), The very same year,
Oliver Perry Hay renamed
Aublysodon mirandus (Leidy
1868) into
Ornithomimus mirandus, which is today seen as a
nomen dubium. In
1933,
William Arthur Parks created the species
Ornithomimus elegans, which is today seen as either
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 (specimen CMN 8632).
Reclassification by Dale Russell At first, it had been common practice to name each newly discovered ornithomimid as a species of
Ornithomimus. In the sixties, this tendency was still very strong, as is shown by the fact that
Oskar Kuhn renamed
Megalosaurus lonzeensis (Dollo
1903) from
Belgium into
Ornithomimus lonzeensis (which is understood today to be an
abelisauroid claw) and
Dale Russell in
1967 renamed
Struthiomimus currellii (Parks 1933) and
Struthiomimus ingens (Parks 1933) into
Ornithomimus currellii and
Ornithomimus ingens, respectively. 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, Dale Russell in
1972 published a
morphometric study. It showed that statistical differences in some proportions could be used to distinguish the two and 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). He considered
Struthiomimus currellii to be a younger synonym 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 one was
Archaeornithomimus. Ornithomimus asiaticus and
Ornithomimus affinis were reassigned to this new genus, becoming
Archaeornithomimus asiaticus and
Archaeornithomimus affinis. The second one was
Dromiceiomimus, meaning "
Emu mimic". This comes 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 this new genus as
Dromiceiomimus brevitertius. He also renamed
Ornithomimus samueli into a second
Dromiceiomimus species:
Dromiceiomimus samueli.
Misassigned to Ornithomimus Two
tibiae from the
Navesink Formation of
New Jersey were 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, which was based on a single vertebra. It was originally named
Coelosaurus by an anonymous author now known to be
Richard Owen in
1854. However,
David Weishampel (
2004) considered "C."
antiquus to be indeterminate among ornithomimosaurs, resulting in it being a
nomen dubium. An SVP
2012 abstract agreed with Weishampel by noting that
Coelosaurus differs from
Gallimimus and
Ornithomimus in the features of the tibiae. In
1988,
Gregory S. Paul classified the various species of
Archaeornithomimus,
Struthiomimus,
Dromiceiomimus, and
Gallimimus to the genus
Ornithomimus. This has found no acceptance among other workers and the name is not presently used by Paul himself.
Present interpretations deformed bones reconstructed on the right 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 Currie studied Russell's 1972 proportional statistics to re-analyze ornithomimid relationships in light of newly discovered specimens. They concluded that there was no justification to separate
Dromiceiomimus from
Ornithomimus, sinking
Dromiceiomimus as a synonym of
O. edmontonicus. However, they did not include the type species
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. Their opinion has been followed by most later authors. Apart from
O. edmontonicus dating to the early Maastrichtian, two other species are presently considered to be possibly valid and are also from the late Maastrichtian.
O. sedens was named by Marsh in 1892 from partial remains found in the
Lance Formation of
Wyoming a 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 to be a species of
Ornithomimus. 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 (MNA P1 1762A) from the
Kaiparowits 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. This conclusion was supported by a
2015 re-description of
O. velox, which found that only the holotype specimen was confidently referable to that species. The authors of this study tentatively referred to the Kaiparowits specimen as
Ornithomimus sp., along with all of the specimens from the Dinosaur Park Formation. ==Description==