''Brachyopterella'' is a genus of prehistoric

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

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 classified ...

family. Two species, both from the

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 ...

period, are known; ''B. pentagonalis'' 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 t ...

and ''B. ritchei'' from

Scotland Scotland (, ) is a country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a border with England to the southeast and is otherwise surrounded by the Atlantic Ocean to 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

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

carapace A carapace is a Dorsum (biology), 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 tor ...

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 (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 ...

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, 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 circula ...

is unknown.

Classification

''B. 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. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start ...

), 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 str ...

References

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

Description

Classification

Species

See also

References