Struthiosaurus
Encyclopedia
Struthiosaurus is one of the smallest known and most basal
Basal (phylogenetics)
In phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...

 genera
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of nodosaurid
Ankylosauria
Ankylosauria is a group of herbivorous dinosaurs of the order Ornithischia. It includes the great majority of dinosaurs with armor in the form of bony osteoderms. Ankylosaurs were bulky quadrupeds, with short, powerful limbs. They are first known to have appeared in the early Jurassic Period of...

 dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...

s, from the Late Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...

 period (Campanian
Campanian
The Campanian is, in the ICS' geologic timescale, the fifth of six ages of the Late Cretaceous epoch . The Campanian spans the time from 83.5 ± 0.7 Ma to 70.6 ± 0.6 Ma ...

-Maastrichtian
Maastrichtian
The Maastrichtian is, in the ICS' geologic timescale, the latest age or upper stage of the Late Cretaceous epoch or Upper Cretaceous series, the Cretaceous period or system, and of the Mesozoic era or erathem. It spanned from 70.6 ± 0.6 Ma to 65.5 ± 0.3 Ma...

) of Austria
Austria
Austria , officially the Republic of Austria , is a landlocked country of roughly 8.4 million people in Central Europe. It is bordered by the Czech Republic and Germany to the north, Slovakia and Hungary to the east, Slovenia and Italy to the south, and Switzerland and Liechtenstein to the...

, Romania
Romania
Romania is a country located at the crossroads of Central and Southeastern Europe, on the Lower Danube, within and outside the Carpathian arch, bordering on the Black Sea...

 and France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

 in Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

. 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.

Taxonomy and Valid Species

Originally described in 1871 by Emanuel Bunzel
Emanuel Bunzel
Emanuel Bunzel, born 1828, was an Austrian paleontologist.In 1871, he described a skull fragment found in an Austrian coal mine years before by colleagues Ferdinand Stoliczka and Eduard Suess as the type specimen for the dinosaur genus Struthiosaurus, the first discovered in the region. Another...

, after remains uncovered by Eduard Suess
Eduard Suess
Eduard Suess was a geologist who was an expert on the geography of the Alps. He is responsible for hypothesising two major former geographical features, the supercontinent Gondwana and the Tethys Ocean.Born in London to a Jewish Saxon merchant, when he was three his family relocated toPrague,...

 and Ferdinand Stoliczka
Ferdinand Stoliczka
Ferdinand Stoliczka was a Moravian palaeontologist who worked in India on paleontology, geology and various aspects of zoology. He died of high altitude sickness during an expedition across the Himalayas.-Early life:Stoliczka was born at the lodge Zámeček near Kroměříž in Moravia...

 in 1855 from the Gute Hoffnung coal mine at Muthmannsdorf near Wiener Neustadt
Wiener Neustadt
-Main sights:* The Late-Romanesque Dom, consecrated in 1279 and cathedral from 1469 to 1785. The choir and transept, in Gothic style, are from the 14th century. In the late 15th century 12 statues of the Apostles were added in the apse, while the bust of Cardinal Melchior Klesl is attributed to...

 in Austria. Many species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 have been referred to Struthiosaurus, most based on very fragmentary and nondiagnostic material. Three valid species are currently recognized by paleontologists: S. austriacus Bunzel, 1871, based on holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...

 PIWU 2349/6; S. transylvanicus Nopcsa
Franz Nopcsa von Felso-Szilvás
Baron Franz Nopcsa von Felső-Szilvás was a Hungarian-born aristocrat, adventurer, scholar, and paleontologist...

, 1915, based on BMNH R4966, a skull and partial skeleton from Romania; and S. languedocensis Garcia and Pereda-Suberbiola, 2003, based on UM2 OLV-D50 A–G CV, a partial skeleton found in 1998 in France. Along with Hungarosaurus
Hungarosaurus
Hungarosaurus tormai is a nodosaurid ankylosaur from the Upper Cretaceous Csehbánya Formation of the Bakony Mountains of western Hungary. It is presently the most completely known ankylosaur from the Cretaceous of Europe...

Ösi, 2005, Struthiosaurus is currently one of only two valid members of the Ankylosauria
Ankylosauria
Ankylosauria is a group of herbivorous dinosaurs of the order Ornithischia. It includes the great majority of dinosaurs with armor in the form of bony osteoderms. Ankylosaurs were bulky quadrupeds, with short, powerful limbs. They are first known to have appeared in the early Jurassic Period of...

 known from Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

.

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. They include: Danubiosaurus anceps Bunzel, 1871; Crataeomus pawlowitschii Seeley, 1881; Crataeomus lepidophorus Seeley 1881; Pleuropeltis suessii Seeley, 1881; Rhadinosaurus alcimus Seeley 1881, Hoplosaurus ischyrus Seeley 1881 and Leipsanosaurus noricus Nopcsa, 1918. Another European ankylosaurid, Rhodanosaurus ludguensis Nopsca, 1929, from Campanian
Campanian
The Campanian is, in the ICS' geologic timescale, the fifth of six ages of the Late Cretaceous epoch . The Campanian spans the time from 83.5 ± 0.7 Ma to 70.6 ± 0.6 Ma ...

-Maastrichtian
Maastrichtian
The Maastrichtian is, in the ICS' geologic timescale, the latest age or upper stage of the Late Cretaceous epoch or Upper Cretaceous series, the Cretaceous period or system, and of the Mesozoic era or erathem. It spanned from 70.6 ± 0.6 Ma to 65.5 ± 0.3 Ma...

-age rocks of southern France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

, is now regarded as a nomen dubium
Nomen dubium
In zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application...

and referred to Nodosauridae incertae sedis
Incertae sedis
, is a term used to define a taxonomic group where its broader relationships are unknown or undefined. Uncertainty at specific taxonomic levels is attributed by , , and similar terms.-Examples:*The fossil plant Paradinandra suecica could not be assigned to any...

.

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
Cervical vertebrae
In vertebrates, cervical vertebrae are those vertebrae immediately inferior to the skull.Thoracic vertebrae in all mammalian species are defined as those vertebrae that also carry a pair of ribs, and lie caudal to the cervical vertebrae. Further caudally follow the lumbar vertebrae, which also...

. Also, though the quadrate-paroccipital process contact is fused in S. transylvanicus, it is unfused in S. austriacus. The skull of S. languedocensis is presently unknown, but the taxon differs from S. transylvanicus in the flatter shape of the dorsal
Dorsum (biology)
In anatomy, the dorsum is the upper side of animals that typically run, fly, or swim in a horizontal position, and the back side of animals that walk upright. In vertebrates the dorsum contains the backbone. The term dorsal refers to anatomical structures that are either situated toward or grow...

 vertebrae. It differs from S. austriacus in the shape of the ischium. (Vickaryous, Maryanska, and Weishampel 2004)

Phylogeny

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. 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
Nodosauridae
Nodosauridae is a family of ankylosaurian dinosaurs, from the Late Jurassic to the Late Cretaceous Period of what are now North America, Asia, Antarctica and Europe.-Characteristics:...

 and suggests it may be one of the most basal ankylosaurs in the clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...

 Ankylosauria
Ankylosauria
Ankylosauria is a group of herbivorous dinosaurs of the order Ornithischia. It includes the great majority of dinosaurs with armor in the form of bony osteoderms. Ankylosaurs were bulky quadrupeds, with short, powerful limbs. They are first known to have appeared in the early Jurassic Period of...

.

Some workers (Vickaryous, Maryanska, and Weishampel 2004) consider the assignment of Struthiosaurus to the Nodosauridae to be provisional, pending further study and future discoveries.
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