Struthiomimus brevetertius was named by Parks (1926). Its type specimen is ROM 797, a partial skeleton, and it is a 3D body fossil. Its type locality is 2 miles below Bleriot ferry (125 ft level) [ROM], which is in a Maastrichtian terrestrial sandstone in the Horseshoe Canyon Formation of Canada.

It was recombined as Ornithomimus brevitertius by Russell (1930), Russell (1933), Russell and Chamney (1967), Paul (1988); it was corrected as Struthiomimus brevitertius by Sternberg (1933), Russell (1964), Russell (1966); it was recombined as Ornithomimus brevetertius by Steel (1970); it was recombined as Dromiceiomimus brevetertius by Osmólska et al. (1972), DeCourten and Russell (1985), Hurum (2001), Zanno et al. (2013), McFeeters et al. (2016); it was synonymized subjectively with Ornithomimus edmontonicus by Makovicky et al. (2004); it was misspelled as Struthiomimus brevitertius by Stromer (1931), Parks (1935), Kuhn (1939); it was recombined as Dromiceiomimus brevitertius by Russell (1972), Coulton (1976), Molnar (1978), Gauthier (1986), Currie (1992), Osmólska (1997), Eberth (1997), Currie (2000), Rauhut (2003), Kobayashi and Barsbold (2006), Currie and Koppelhus (2015), Macdonald and Currie (2019).