Eurypterus - Species

Species

Species belonging to the genus, their diagnostic descriptions, synonyms (if present), and distribution are as follows:

• Eurypterus

• ?Eurypterus cephalaspis – Silurian, England

Uncertain placement. Only 3 of the specimens described in 1856 are probably Eurypterus, the rest probably belonged to Hughmilleriidae. Its name means "shield head", from Greek κεφαλή (kephalē, head), and ἀσπίς (aspis, shield or bowl). Specimens recovered from Herefordshire, England.

• Eurypterus dekayi – Silurian, USA & Canada

No raised scales on the posterior margin of the carapace or of the three front-most tergites. The rest of the tergites each have four raised scales. Four to six spines on each podomere of Appendages III and IV. Pretelson has large, rounded epimera without ornamentation on the margins. The species is very similar to E. laculatus. The species is named after James Ellsworth De Kay. Specimens recovered from New York and Ontario.

• Eurypterus flintstonensis – Silurian, USA

Probably a synonym of E. remipes or E. lacustris. Probably named after Flintstone, Georgia (?). Specimen recovered from eastern United States.

• Eurypterus hankeni – Silurian, Norway

Small Eurypterus species, averaging at 10 to 15 centimetres (3.9 to 5.9 in) long. The largest specimen found is about 20 to 25 centimetres (7.9 to 9.8 in) in length. They can be distinguished by pustules and six scales at the rear margin of their carapaces. Appendages I to IV has two spines on each podomere. The postabdomen have small epimera. The pretelson has long pointed epimera. Telson has striations near its attachment to the pretelson. The species is named after Norwegian paleontologist Nils-Martin Hanken, of the University of Tromsø. Found in the Steinsfjorden Formation of Ringerike, Norway.

• Eurypterus henningsmoeni – Silurian, Norway

Eurypterus with broad paddles and metastoma. Postabdomen has small epimera. Pretelson has large rounded epimera with imbricate scales (overlapping, similar to fish scales). It is very similar and closely related to E. tetragonophthalmus. The species was named after the Norwegian paleontologist Gunnar Henningsmoen. Found in Bærum, Norway.

• Eurypterus laculatus – Silurian, USA & Canada

The visual area of the compound eyes of this species are surrounded by depressions. The ocelli and the ocellar mound are small. No pustules or raised scales on the carapace or the first tergite. It is probably closely related to E. dekayi. Its specific name means "four-cornered", from Latin laculatus (four-cornered or checkered). Found in New York and Ontario.

• Eurypterus lacustris – Silurian, USA & Canada

One of the two most common Eurypterus fossils found. It is very similar to E. remipes and often found in the same localities, but the eyes are placed at a more posterior position on the carapace of E. lacustris. It is also slightly larger with a slightly narrower metastoma. Its status as a distinct species was once disputed before diagnostic analysis by Tollerton in 1993. Its specific name means "from a lake", from Latin lacus (lake). Found in New York and Ontario.

• Eurypterus leopoldi – Silurian, Canada

Frontmost tergite is reduced. Metasoma is rhombiovate in shape with tooth-like projections at the anterior part. The pretelson has serrated edges. the epimera are large, semi-angular with angular striations. The telson is styliform with large angular striations interspersed among smaller more numerous striations. The species is named after Port Leopold and the Leopold Formation were they were collected. Found in the Leopold Formation of Somerset Island, Canada.

• Eurypterus megalops – Silurian, USA

Specific name means "large eye", from Greek μέγας (megas, big or large) and ὤψ (ōps, eye). Discovered in New York, USA.

• ?Eurypterus minor – Silurian, Scotland

Small Eurypterus with large pustules on the carapace and abdomen. Does not possess the scale ornamentation found in other species of Eurypterus. It is the earliest known species of Eurypterus. They have large palpebral lobes (part of "cheeks" of the carapace adjacent to the compound eyes), making it easy to mistake their eyes for being oval. This enlargement is more typical of the genus Dolichopterus and it may actually belong to Dolichopteridae. The specific name means "smaller", from Latin minor. Found in the Reservoir Formation of Pentland Hills, Scotland.

• Eurypterus ornatus – Silurian, USA

Ornamentation of pustules on the entire surface of the carapace and at least the first tergite. Does not possess raised scales. Its specific name means "adorned", from Latin ōrnātus (adorned, ornate). Recovered from Fayette, Ohio.

• Eurypterus pittsfordensis – Silurian, USA

The posterior margin of the carapace has three raised scales. Apendages II to IV has two spines per podomere. The metastoma is rhomboid in shape with a deep notch at the front part. The postabdomen has serrated fringes at the middle with small angular epimera at the sides. The pretelson has large, semiangular epimera with angular striations at the margins. The telson is styliform with sparse angular striations at the margins. The name of the species comes from its place of discovery – the Salina shale formations of Pittsford, New York.

• Eurypterus quebecensis – Silurian, Canada

Has six raised scales on the posterior margin of the carapace but does not possess pustule ornamentation. It is named after the location it was recovered from – Quebec, Canada.

• Eurypterus remipes – Silurian, USA, Canada

The most common Eurypterus species. Has four raised scales at the posterior margin of the carapace. Appendages I to IV has two spines on each podomere. Postabdomen has small epimera. Pretelson has small, semiangular epimera with imbricate scale ornamentation at the margins. The telson has serrated margins along most of its length. It is very similar to E. lacustris and can often only be distinguished by the position of the eyes. The specific name means "oar-foot", from Latin rēmus (oar) and pes (foot). Found in New York and Ontario.

• Eurypterus serratus – Silurian, Sweden

Similar to E. pittsfordensis and E. leopoldi but can be distinguished by the dense angular striations on their styliform telson. The specific name means "serrated", from Latin serrātus (sawn ). Originally discovered from Gotland, Sweden.

• Eurypterus tetragonophthalmus – Silurian, Ukraine & Estonia

Four raised scales on the posterior margin of the carapce. Appendages II to IV each have two spines on each podomere. Postabdomen has small epimera. The pretelson has large, rounded epimera with imbricate scale ornamentation at the margins. Telson has imbricate scale ornamentations at the margins of the base which become serrations towards the tip. The specific name means "four-edged eye", from Greek τέσσαρες (tessares, four), γωνία (gōnia, angle), and ὀφθαλμός (ophthalmos, eye). Found in the Rootsiküla Formation of Saaremaa (Ösel), Estonia with additional discoveries in Ukraine, Norway, and possibly Moldova and Romania.

The list does not include the large number of fossils previously classified under Eurypterus. Most of them are now reclassified to other genera, identified as other animals (like crustaceans) or pseudofossils, or remains of doubtful placement. Classification is based on Dunlop et al.(2011).