''Brachyopterella'' 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; ''B. pentagonalis'' 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 ...

and ''B. ritchei'' 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 ...

.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

''Brachyopterella'' was a small stylonurine eurypterid with a pentagonal

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 little to no marginal rim and a concave base. The eyes were oblique, very long, banana-shaped, close-set and placed anteriorly on the carapace. Axes converged and crossed a short distance in front of the eyes. The

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 ...

were placed well forward between the eyes and the epistoma was well developed. The legs increased in size gradually, with the first three having short opposable spines at the end of each joint and the last two walking legs being longer but lacking spines. The carapace was smooth and the legs were covered in granulations. 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 ...

is unknown.

Classification

''Brachyopterella pentagonalis'' was originally named as a species of the closely related ''

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. ...

'', differences in the shape of the carapace and the eyes allowed them to be separated into different genera.

Species

''Brachyopterella'' contains two valid species, with one other species turning out to have been a pseudofossil. * ''Brachyopterella pentagonalis'' Størmer, 1934 - Ringerike, Norway (

) * ''Brachyopterella ritchiei'' Clarke & Ruedemann, 1912 - Slot Burn, Scotland (

) Invalid or reassigned species are listed below: * ''Brachyopterella magna'' Clarke & Ruedemann, 1912 - New York (

Ordovician The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era, and the second of twelve periods of the Phanerozoic Eon (geology), Eon. The Ordovician spans 41.6 million years f ...

), a

pseudofossil Pseudofossils are inorganic objects, markings, or impressions that might be mistaken for fossils. Pseudofossils may be misleading, as some types of mineral deposits can mimic lifeforms by forming what appear to be highly detailed or organized st ...

References

{{Taxonbar, from=Q4953357 Rhenopteroidea Silurian eurypterids Silurian arthropods of Europe Eurypterids of Europe

Description

Classification

Species

See also

References