Struthiosaurus (Latin struthio = ostrich + Greek sauros = lizard) is one of the smallest known and most basal genera of nodosaurid dinosaurs, from the Late Cretaceous period (Campanian-Maastrichtian) of Austria, Romania and France in Europe. It was protected by body armour. Although estimates of its length vary, it may have been as small as 2.2 metres (7.2 ft) long.
Struthiosaurus was originally by Bunzel considered a predator that he assigned to the new taxon Ornithocephala ("Bird Heads"). The generic name is a reference to the affinities with birds shown by traits in the skull. The first to understand it represented an armoured dinosaur was Nopcsa who in 1902 placed it in the Acanthopholididae. He later corrected its name to Acanthopholidae. Walter Coombs in 1978 stated it was a nodosaurid.
Cladistic analysis of Struthiosaurus (Ösi, 2004) indicates that the taxon is a basal member of the Nodosauridae and suggests it may be one of the most basal ankylosaurs in the clade Ankylosauria.
Some workers (Vickaryous, Maryanska, and Weishampel 2004) consider the assignment of Struthiosaurus to the Nodosauridae to be provisional, pending further study and future discoveries.