''Kiaeropterus'' is a genus of prehistoric

eurypterid Eurypterids, often informally called sea scorpions, are a group of extinct marine arthropods that form the Order (biology), order Eurypterida. The earliest known eurypterids date to the Darriwilian stage of the Ordovician period, 467.3 Myr, mil ...

classified as part of the

Rhenopteridae The Rhenopteridae are a family of eurypterids, an extinct group of chelicerate arthropods commonly known as "sea scorpions". The family is the only family currently contained in the superfamily Rhenopteroidea, one of four superfamilies classifie ...

family. Two species, both from the

Silurian The Silurian ( ) is a geologic period and system spanning 23.5 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 third and shortest period of t ...

period, are known; ''K. cyclophthalmus'' from

Scotland Scotland is a Countries of the United Kingdom, country that is part of the United Kingdom. It contains nearly one-third of the United Kingdom's land area, consisting of the northern part of the island of Great Britain and more than 790 adjac ...

and ''K. ruedemanni'' from

Norway Norway, officially the Kingdom of Norway, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. The remote Arctic island of Jan Mayen and the archipelago of Svalbard also form part of the Kingdom of ...

.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 A carapace is a dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tortoises, the unde ...

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 (biology), 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 sy ...

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. Wasps, bees and a ...

not wider than the carapace, unlike in some eurypterids. The appendages V and VI were non-spiniferous and simple with individual

podomere The arthropod leg is a form of jointed appendage of arthropods, usually used for walking. Many of the terms used for arthropod leg segments (called podomeres) are of Latin origin, and may be confused with terms for bones: ''coxa'' (meaning hip, : ...

s having pronounced ridges. The genus is very poorly known. The

type species In International_Code_of_Zoological_Nomenclature, 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 spe ...

''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 or ocellus (sometimes called a pigment pit) is a form of eye or an optical arrangement which has a single lens without the sort of elaborate retina that occurs in most vertebrates. These eyes are called "simple" to distinguish the ...

, 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 hindmost division of the body of an arthropod. Depending on the definition, the telson is either considered to be the final segment (biology), segment of the arthropod body, or an additional division that is not a true segm ...

History of discovery

''Kiaeropterus 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 23.5 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 third and shortest period of t ...

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 hills take their name from the hamlet of Pe ...

near

Edinburgh Edinburgh is the capital city of Scotland and one of its 32 Council areas of Scotland, council areas. The city is located in southeast Scotland and is bounded to the north by the Firth of Forth and to the south by the Pentland Hills. Edinburgh ...

. This specimen was purchased as part of a larger collection of fossil specimens by the Edinburgh Museum of Science and Art 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 depos ...

), 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 ''Brachyopterus'' is a genus of prehistoric eurypterid of the family Rhenopteridae. It is one of the earliest known eurypterids, having been recovered from Middle Ordovician deposits in Montgomeryshire, Wales.Dunlop, J. A., Penney, D. & Jekel, D. ...

'', 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

References

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

Description

History of discovery

Classification

See also

References