''Kiaeropterus'' is a genus of prehistoric

eurypterid Eurypterids, often informally called sea scorpions, are a group of extinct arthropods that form the order Eurypterida. The earliest known eurypterids date to the Darriwilian stage of the Ordovician period 467.3 million years ago. The group is l ...

classified as part of the Rhenopteridae family. Two species, both from the Silurian period, are known; ''K. cyclophthalmus'' from

Scotland Scotland (, ) is a Countries of the United Kingdom, country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a Anglo-Scottish border, border with England to the southeast ...

and ''K. ruedemanni'' from

Norway Norway, officially the Kingdom of Norway, is a Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of the Scandinavian Peninsula. The remote Arctic island of Jan Mayen and the ...

.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 http://wsc.nmbe.ch, version 16.0 http://www.wsc.nmbe.ch/resources/fossils/Fossils16.0.pdf (PDF).

Description

''Kiaeropterus'' was a small eurypterid, with ''K. cyclophthalmus'' reaching lengths of about 6,6 cm. It had a subquadrate carapace with broad marginal rims. The eyes were large, covering about a third of the length of the carapace. The

metasoma The metasoma is the posterior part of the body, or tagma, of arthropods whose body is composed of three parts, the other two being the prosoma and the mesosoma. In insects, it contains most of the digestive tract, respiratory system, and circul ...

was narrow and the

mesosoma The mesosoma is the middle part of the body, or tagma, of arthropods whose body is composed of three parts, the other two being the prosoma and the metasoma. It bears the legs, and, in the case of winged insects, the wings. In hymenopterans of ...

not wider than the carapace, unlike in some eurypterids. The appendages V and VI were non-spiniferous and simple with individual podomeres having pronounced ridges. The genus is very poorly known. The

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specime ...

''K. ruedemanni'' is known only from two specimens, PMO HI733 and HI711. Two additional specimens may be referrable to the species, PMO HI661 and HI678, though they are seemingly missing. ''K. cyclophthalmus'', differentiated by its wider carapace and slightly larger and more circular palpebral lobes along with its larger

ocelli A simple eye (sometimes called a pigment pit) refers to a form of eye or an optical arrangement composed of a single lens and without an elaborate retina such as occurs in most vertebrates. In this sense "simple eye" is distinct from a multi-l ...

, is known only from one almost complete specimen, NMS G.1885.26.72P, that lacks most of the prosomal appendages and the

telson The telson () is the posterior-most division of the body of an arthropod. Depending on the definition, the telson is either considered to be the final segment of the arthropod body, or an additional division that is not a true segment on accou ...

History of discovery

''K. cyclophthalmus'' was originally described as ''

Eurypterus ''Eurypterus'' ( ) is an extinct genus of eurypterid, a group of organisms commonly called "sea scorpions". The genus lived during the Silurian period, from around 432 to 418 million years ago. ''Eurypterus'' is by far the most well-studied and ...

cyclophthalmus'' based on a single specimen from the

Lower Silurian The Silurian ( ) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the shortest period of the Paleozo ...

of the

Pentland Hills The Pentland Hills are a range of hills southwest of Edinburgh, Scotland. The range is around in length, and runs southwest from Edinburgh towards Biggar and the upper Clydesdale. Etymology The name is first recorded for the farm of Pentla ...

near

Edinburgh Edinburgh ( ; gd, Dùn Èideann ) is the capital city of Scotland and one of its 32 council areas. Historically part of the county of Midlothian (interchangeably Edinburghshire before 1921), it is located in Lothian on the southern shore of t ...

. This specimen was purchased as part of a larger collection of fossil specimens by the

Edinburgh Museum of Science and Art The National Museum of Scotland in Edinburgh, Scotland, was formed in 2006 with the merger of the new Museum of Scotland, with collections relating to Scottish antiquities, culture and history, and the adjacent Royal Scottish Museum (opened in ...

in 1885. When it was described in 1892, eurypterid taxonomy had not been firmly established or thoroughly researched and as a result, most new specimens were classified as part of the genus ''

''. When re-studied, the specimen was found to share considerably more features with the

Stylonurina Stylonurina is one of two suborders of eurypterids, a group of extinct arthropods commonly known as "sea scorpions". Members of the suborder are collectively and informally known as "stylonurine eurypterids" or "stylonurines". They are known from ...

than with ''Eurypterus'' (which is classified as part of the

Eurypterina Eurypterina is one of two suborders of eurypterids, an extinct group of chelicerate arthropods commonly known as "sea scorpions". Eurypterine eurypterids are sometimes informally known as "swimming eurypterids". They are known from fossil deposi ...

), for instance its large eyes. Further comparisons with what limited material was known of ''K. ruedemanni'' allowed it to be placed into the genus ''Kiaeropterus''.

Classification

The exact phylogenetic position of ''Kiareopterus'' is uncertain. It was originally classified as a stylonurid by Waterston (1979). Later studies revealed important similarities with '' Brachyopterus'', including the large eyes converging anteriorly, the lack of a cuticular ornament and simple rectangular appendage podomeres with pronounced ridges. These similarities prompted it to be classified as a close relative of ''Brachyopterus'', within the family Rhenopteridae.

References

{{Taxonbar, from=Q6403674 Rhenopteroidea Silurian eurypterids Silurian arthropods of Europe Eurypterids of Europe

Description

History of discovery

Classification

See also

References