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Temporal range: Devonian
Stylonurus BW.jpg
Restoration of S. powriensis.
Scientific classification edit
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Chelicerata
Order: Eurypterida
Superfamily: Stylonuroidea
Family: Stylonuridae
Genus: Stylonurus
Page, 1856
Type species
Stylonurus powriensis
Page, 1856
Other species
  • S?. shaffneri Willard, 1933

Stylonurus is a genus of prehistoric eurypterid of the family Stylonuridae. The genus contains two species; Stylonurus powriensis from the Devonian of Scotland and Stylonurus shaffneri from the Devonian of Pennsylvania.[1]

The assignment of S. shaffneri to the genus is doubtful. A previously assigned species, S. ensiformis, is today regarded as synonymous with S. powriensis.[1]


Stylonurids, which lived from the Ordovician to Lower Permian periods, were small to very large forms with scales developing into tubercules and knobs. The prosoma (head) exhibited variable shape, with arcuate compound eyes located subcentrally, or anteriorly. Their abdomens were slender. Their walking legs were long and powerful, sometimes characterized by spines. Most genera did not have swimming legs.[2]

Stylonurus is distinguishable from other stylonurids by their smooth surface, and the greatly elongated 5th (last) pair of walking legs, which reached as far as the telson, which was long and styliform. The prosoma (head) varied from semiovate to subrectangular.[2]


  1. ^ a b Dunlop, J. A., Penney, D. & Jekel, D. 2015. A summary list of fossil spiders and their relatives. In World Spider Catalog. Natural History Museum Bern, online at, version 16.0 (PDF).
  2. ^ a b Størmer, L 1955. Merostomata. Treatise on Invertebrate Paleontology, Part P Arthropoda 2, Chelicerata, P: 36.

See also[edit]