Struthiosaurus (Latin struthio = ostrich + Greek sauros = lizard) is a genus of nodosaurid dinosaurs, from the Late Cretaceous period (Santonian-Maastrichtian) of Austria, Romania, France and Hungary in Europe.

[2][3][4][5] In 1859, geologist Eduard Suess at the Gute Hoffnung coal mine at Muthmannsdorf near Wiener Neustadt in Austria, discovered a dinosaur tooth on a stone pile.

The search proved fruitless at first but ultimately a thin marl layer was discovered, intersected by an obliquely sloping mine shaft, which contained an abundant number of various bones.

One of them was the genus Struthiosaurus based on a single partial portion of the posterior end of the skull, largely consisting of the braincase.

In Ankylosauria, the rump is so flat that the upper part of the rib shafts sticks out sideways, which rotates the short tuberculum to the diapophysis, its vertebral contact facet.

[9] A number of invalid taxa have been shown to be junior synonyms of Struthiosaurus austriacus, most of them created when Harry Govier Seeley in 1881 revised the Austrian material.

[11] Another European ankylosaurid, Rhodanosaurus ludguensis Nopcsa, 1929, from Campanian-Maastrichtian-age rocks of southern France, is now regarded as a nomen dubium and referred to Nodosauridae incertae sedis.

[12] The three valid species of Struthiosaurus differ from one another in that S. austriacus is smaller than S. transylvanicus and possesses less elongate cervical vertebrae.

The back of the head was otherwise not very reptilian as it was low, compact, fused and convex in a gradual curve towards the skull-roof.

Bunzel sent a drawing and description to Professor Thomas Huxley in London, at the time one of the few dinosaur experts.

[15] Cladistic analysis of Struthiosaurus indicates that the taxon is a member of the Nodosauridae and suggested it may be one of the most basal ankylosaurs in the clade Ankylosauria.

An analysis by Ösi in 2005, describing the taxon Hungarosaurus, found that while being younger in age than other nodosaurids, Struthiosaurus was one of the more basal taxa, although many features could not be coded for it.