Eysyslopterus

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Eysyslopterus
Temporal range:
Ma
↓
Restoration of the carapace of E. patteni based on Tetlie and Poschmann's of 2008
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Chelicerata
Order: †Eurypterida
Superfamily: †Adelophthalmoidea
Family: †Adelophthalmidae
Genus: †Eysyslopterus
Tetlie & Poschmann, 2008
Type species
†Eysyslopterus patteni
Størmer, 1934
Synonyms
  • Hughmilleria patteni Størmer, 1934
  • Hughmilleria (Nanahughmilleria) patteni Kjellesvig-Waering, 1961
  • Nanahughmilleria patteni Kjellesvig-Waering & Leutze, 1966

Eysyslopterus is a

zoologist
who discovered the only known fossil of Eysyslopterus.

Eysyslopterus is a little-known

lagoonal
quiet community along other eurypterid species.

Description

Size comparison of E. patteni

Like the other

adelophthalmid eurypterids, Eysyslopterus was a small eurypterid. The total size of the only known specimen is estimated at only 8 centimetres (3.1 inches),[1] far from the largest adelophthalmids like Adelophthalmus khakassicus of 32 cm (12.6 in) in length.[2]

Eysyslopterus is a little known eurypterid, with only one specimen collected that only preserves the

eyes were reniform (bean-shaped) and with a thin and light-colored test (external "shield") on its surface. They measured 4.5 mm (0.18 in) in length. The ocelli (simple eyes) were located in the posterior half of the prosoma and consisted of two circular spots. The posterior part was smooth, but the previous part had a distinctive ornamentation. This ornamentation extended until the end of the eyes and was composed of transverse lines developed as deep furrows.[3]

Eysyslopterus was a basal ("primitive") genus with respect to the rest of adelophthalmids, with the eyes closer to the margin than to the ocelli, suggesting that the eyes migrated towards a central position from the basal genera to Adelophthalmus.[4]

History of research

Restoration of the carapace of Eysyslopterus patteni based on Størmer's of 1934

Eysyslopterus is only known from one single specimen (and is therefore the

zoologist William Patten during his extensive explorations at the Rootsikula Formation in Saaremaa, Estonia (then part of the Soviet Union). During a meeting between Patten and the Norwegian paleontologist and geologist Leif Størmer in 1932, Størmer observed Patten's private collection of eurypterids, among which he recognized a carapace of a new unknown species. He described it in 1934 as belonging to the genus Hughmilleria patteni, named after Patten, who died months after the meeting. Størmer noticed several differences between his new species and other Hughmilleria species, essentially the shape of the prosoma and the form or position of the eyes. He also suggested a close relationship between H. patteni and other species, especially the Scottish species H. lanceolata.[3]

However, in 1961, the American paleontologist Erik Norman Kjellesvig-Waering split Hughmilleria in two

Viking name for Saaremaa, and the second part by opterus, a suffix commonly used in eurypterids which means "wing" (and therefore, translated as "wing of Eysysla").[4]

Classification

Eysyslopterus is classified as part of the family Adelophthalmidae, the only

superfamily Adelophthalmoidea.[6] E. patteni was originally described as a species of the genus Hughmilleria,[3] but it was considered different enough to represent a new separate genus in 2008.[4]

Eysyslopterus is considered to be the most basal adelophthalmid genus due to the position of its eyes. These are placed closer to the margin than to the ocelli, in contrast to any other adelopthalmid. In fact, the carapace of Eysyslopterus and other basal genera belonging to superfamilies,

sister taxon of a group formed by Pterygotioidea and Adelophthalmoidea, but until more fossil material is found this can not be proven.[4]

Restoration of the related Adelophthalmus, type genus of Adelophthalmidae

The

infraorder of eurypterids (Adelophthalmoidea, Pterygotioidea and the waeringopteroids), as inferred by Tetlie and Poschmann in 2008, based on the results of a 2008 analysis specifically pertaining to the Adelophthalmoidea and a preceding 2004 analysis.[4]

Diploperculata

Paleoecology

The single known specimen of Eysyslopterus has been recovered from

lagoonal quiet community. The lithology (the physical characteristics of the rocks) of the zone was composed of mudcrack and burrows of dolomite and limestone.[8]

See also

References

  1. PMID 19828493. Supplemental material
    .
  2. S2CID 91741388
    .
  3. ^
    OCLC 1006783631
    .
  4. ^
    S2CID 59488956
    .
  5. JSTOR 1301214
    .
  6. ^ Dunlop, J. A., Penney, D. & Jekel, D. 2018. A summary list of fossil spiders and their relatives. In World Spider Catalog. Natural History Museum Bern.
  7. S2CID 140668235
    .
  8. ^ "Eurypterid-Associated Biota of the Rootsikula Horizon, Saaremaa, Estonia: Rootsikula, Estonia". The Paleobiology Database.
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