been used for wing feather support instead. Speed The legs (hind limbs) of Struthiomimus were long, powerful and seemingly well-suited to rapid running, much like an ostrich. The supposed speed of Struthiomimus was, in fact, its main defense from predators (although it may also have been able to lash out with its hind claws when cornered), such as the dromaeosaurids (e.g. Saurornitholestes and Dromaeosaurus) and tyrannosaurs (e.g. Daspletosaurus and Gorgosaurus), which lived at the same time. It is estimated to have been able to run at speeds between . Paleoecology Fossil remains of S. altus are only known definitively from the Oldman Formation, dated to between 78 and 77 million years ago during the Campanian stage of the late Cretaceous period. A younger species (which has not yet been named), which apparently differed from S. altus in having longer, more slender hands, is known from several specimens found in the Horseshoe Canyon Formation and lower Lance Formation, between 69 and 67.5 million years ago (early Maastrichtian). See also Timeline of ornithomimosaur research References Further reading Cranfield, I. (2004). The Illustrated Directory of Dinosaurs and other Prehistoric Creatures (pp. 30–33). Greenwich Editions. . External links Fossils of Canada Ornithomimids Campanian genus first appearances Maastrichtian life Late Cretaceous dinosaurs of North America Hell Creek fauna Horseshoe Canyon fauna Lance fauna Oldman fauna Paleontology in Alberta Fossil taxa described in 1917 Taxa named by Henry Fairfield Osborn