Ornithomimus tenuis
Ornithomimus tenuis is based on USNM 5814, fragmentary fossils found by John Bell Hatcher in 1888 near "Cow Island" in the Judith River Formation of Blaine County, Montana, which seem to belong to a tyrannosauroid of some ilk. Ornithomimus grandis
Ornithomimus grandis was named by O.C. Marsh in 1890 based on a foot bone, now lost, that John Bell Hatcher discovered at "Cow Creek" in the Eagle Sandstone Formation of Fergus County, Montana, in 1888. Ornithomimus grandis was synonymised with the dubious Deinodon horridus by Matthew and Brown in 1922, but it may actually be the very first specimen of a certain critter we now know as Tyrannosaurus rex. Ornithomimus sedens
O. C. Marsh was convinced that Ornithomimus was an ornithopod until USNM 4736—a partial skeleton that J. B. Hatcher and A. L. Sullins found in the Lance Formation of Niobrara County, Wyoming, in 1891—showed this not to be the case. Marsh named these remains Ornithomimus sedens a year later and moved them to Struthiomimus sedens a year after that. Ornithomimus minutus
Ornithomimus minutus was named in tandem with Ornithimimus sedens, based on YPM 1049, a foot bone (metatarsus) found by O. A. Peterson in the Lance Formation of Niobrara County, Wyoming. It spent a while as Dromaeosaurus minutus (?) but seems to belong to an alvarezsaurid, possibly Mononykus. Ornithomimus altus
Ornithomimus altus was named in 1902 by Lawrence Lambe, based on CMN 930, hindlimbs found in 1901 in the Oldman Formation of Alberta by Hatcher and Brown. It was a better specimen of this critter, discovered by Barnum Brown in 1914 at the same site, that prompted Henry Fairfield Osborn to move Ornithomimus altus to a new subgenus Struthiomimus (Ornithomimus) in 1916. Dale Russell made Struthiomimus a standalone genus in 1972. Some of the remains that Russell assigned here (ROM 1790; a partial skull, a nearly complete pelvis, both hind limbs, foot bones, and part of a tail) were renamed Rativates evadens by McFeeters et al. in 2016. Ornithomimus affinis
Ornithomimus affinis was plucked from a bunch of unassociated foot bones (USNM 5453, 5652, 5684, 5703, 5704, 6107, 6108, 8456) that John Bell Hatcher and Arthur Bibbins had discovered at several sites across the Arundel Formation of Maryland in 1888. These remains were used by Marsh to establish Allosaurus medius in 1888. However, most of them were referred to Dryosaurus grandis by Richard Swann Lull in 1911. In 1920, Gilmore realised the remains of Dryosaurus grandis belonged to an ornithomimosaur, but, as an Ornithomimus grandis had already been named by O.C. Marsh based on a foot bone from the Eagle Sandstone Formation, he settled on Ornithomimus affinis instead. In 1972, Dale Russell assigned this material to Archaeornithomimus as Archaeornithomimus affinis. Ornithomimus brevitertius
In 1930, Loris Russell renamed Struthiomimus brevetertius (Parks 1926) into Ornithomimus brevitertius. Dale Russell assigned this material to Dromiceiomimus (emu mimic) as Dromiceiomimus brevitertius in 1972. But Peter Makovicky brushed it off as a junior synonym of Ornithomimus edmontonicus in 2004. Ornithomimus samueli
In 1930, Loris Russell renamed Struthiomimus samueli (Parks 1928), which was based on ROM 840, a partial skeleton from RTMP Quarry 20 in the Dinosaur Park Formation, Steveville, Canada, into Ornithomimus samueli. Dale Russell assigned this material to Dromiceiomimus as Dromiceiomimus samueli in 1972. But Peter Makovicky brushed it off as a junior synonym of Ornithomimus edmontonicus in 2004. Ornithomimus mirandus
In 1920, Oliver Perry Hay renamed Aublysodon mirandus (Leidy 1868) into Ornithomimus mirandus even though Lawrence Lambe had already assigned its remains to Struthiomimus in 1902. Because Othniel Charles Marsh had nominated a single tooth (ANSP 9535, collected by Ferdinand Vandeveer Hayden from the Judith River Badlands of Montana in 1854) as the Aublysodon name-bearing specimen in 1892 and ornithomimids are toothless, it's safe to say that Ornithomimus mirandus is a dubious name. So is Aublysodon! Ornithomimus elegans
In 1933, William Arthur Parks created Ornithomimus elegans based on ROM 781, a foot from Alberta. In 1989, Phil Currie moved this foot, along with CMN 2690, a small lower jaw that Joël Cracraft had named Caenagnathus sternbergi in 1971, to Elmisaurus elegans. Hans-Dieter Sues moved them both to Chirostenotes elegans in 1997, which was highly contentious at the time. Nicholas Longrich renamed it Leptorhynchos elegans in 2013. Ornithomimus asiaticus
In 1933, Gilmore named Ornithomimus asiaticus for material found in the Iren Dabasu Formation of Inner Mongolia by Roy Chapman Andrews in 1923. In 1972, Dale Russell used this material to raise a new dinosaur, Archaeornithomimus asiaticus. AMNH 6565, a foot, is the lectotype. Ornithomimus lonzeensis
Ornithomimus lonzeensis was initially named Megalosaurus lonzeensis (Dollo, 1903) based on a single finger claw from Lonzee in Belgium that was first mentioned back in 1883. After a stint as "Ornithomimodorum gen. a" (von Huene, 1926), Oscar Kuhn assigned it to Ornithomimus in 1962. Glut referred it to Struthiomimus lonzeensis in 1997, but today, it's believed to be an abelisauroid. Ornithomimus currellii
Ornithomimus currellii, based on ROM 851, a skeleton from the Horseshoe Canyon Formation of Munson Ferry, Canada, was originally known as Struthiomimus currellii (Parks 1933). It was renamed in 1967 by Dale Rusell, who lumped it into Ornithomimus edmontonicus in 1972. Ornithomimus ingens
Ornithomimus ingens—based on ROM 852, found 1.5 miles below Munson Ferry, Canada—was originally known as Struthiomimus ingens (Parks 1933) until Dale Russel renamed it in 1967. Russel assigned it to Dromiceiomimus (emu mimic) as Dromiceiomimus brevitertius in 1972. But Peter Makovicky brushed it off as a junior synonym of Ornithomimus edmontonicus in 2004. Ornithomimus bullatus was originally known as Gallimimus bullatus. It was moved to Ornithomimus by Gregory S. Paul in 1988, but this found no support whatsoever. Even Paul himself doesn't use this name! Ornithomimus antiquus
The consensus of many is that the first dinosaur that would become Ornithomimus was named Coelosaurus antiquus (Antique Hollow Lizard), based on two shins from the Navesink Formation of New Jersey, by Joseph Leidy in 1865. Its remains were assigned to Ornithomimus as Ornithomimus antiquus by Horner and Baird in 1979, which, under normal circumstances, would have made Ornithomimus a junior synonym of Coelosaurus because the latter was named 25 years earlier. However, it transpired that the name Coelosaurus had already been assigned to a single vertebra by Richard Owen in 1854. Furthermore, there's a growing theory that Ornithomimus antiquus may not even be an ornithomimid.