Struthiomimus remains were actually known all the way back to 1901 but were interpreted by Lawrence Lambe to belong to Ornithomimus Altus, the first ornithomimid to be named. In 1917 however, Henry Fairfield Osborn identified key differences in the bones, especially the hands, and renamed the remains as a new genus, Struthiomimus. Despite the difference, Struthiomimus and Ornithomimus are still very much like one another, and between them, they seem to have been the two most common types of ornithomimid active in North America.