Dale Russell
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 an abelisauroid claw), and Dale Russell 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 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 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 "Dromiceiomimus brevitertius". He renamed "Ornithomimus samueli" into a second "Dromiceiomimus" species: "Dromiceiomimus samueli".