The first known fossils of Struthiomimus were named as Ornithomimus sedens by Othniel Charles Marsh. The bipedal Struthiomimus was about 4.3mts long and 1.4mts tall and weighed around 150 kilograms. Struthiomimus had a usual build and skeletal structure for an ornithomimid and its eyes were large, jaws were toothless. Its vertebral column had ten neck vertebrae, sixteen back vertebrae, six hip vertebrae, and an unknown number of tail vertebrae. Its legs were only moderately elongate and its feet were elongate with three toes tipped by claws.
Struthiomimus, being a member of Coelurosauria, most likely had feathers especially if the Ornithomimosauria and the alvarezsauridae are closely related. It appears like modern ground birds such as ostriches and emus. It’s believed to be the fastest dinosaurs and it may able to run faster than ostriches.