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''Brachyopterus'' is a genus of prehistoric http://wsc.nmbe.ch , version 16.0 http://www.wsc.nmbe.ch/resources/fossils/Fossils16.0.pdf (PDF). Though other species have been assigned to it in the past, ''Brachyopterus'' is today recognized as containing one valid species, ''B. stubblefieldi''.
''Brachyopterus'' is distinguished by its small size, compound eyes with axes converging anteriorly on a subtrapezoid to subpentagonal prosoma (head). All of its legs are walking legs; the first three pairs are short with spines, except when modified into clasping organs; the last two pairs are moderately long, keeled and tapering in width to terminal claws. The last leg falls short of the penultimate abdominal segment. The abdomen is narrow and ends in a short styliform
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 ...
of the family 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 ...
. It is one of the earliest known eurypterids, having been recovered from Middle Ordovician
The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya.
The ...
deposits in Montgomeryshire
Montgomeryshire, also known as ''Maldwyn'' ( cy, Sir Drefaldwyn meaning "the Shire of Baldwin's town"), is one of thirteen historic counties of Wales, historic counties and a former administrative county of Wales. It is named after its county tow ...
, Wales
Wales ( cy, Cymru ) is a Countries of the United Kingdom, country that is part of the United Kingdom. It is bordered by England to the Wales–England border, east, the Irish Sea to the north and west, the Celtic Sea to the south west 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 Description
''Brachyopterus'' is distinguished by its small size, compound eyes with axes converging anteriorly on a subtrapezoid to subpentagonal prosoma (head). All of its legs are walking legs; the first three pairs are short with spines, except when modified into clasping organs; the last two pairs are moderately long, keeled and tapering in width to terminal claws. The last leg falls short of the penultimate abdominal segment. The abdomen is narrow and ends in a short styliform 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 ...
. ''Brachyopterus'' date from the Middle 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 ...
.Størmer, L. 1955. Merostomata. ''Treatise on Invertebrate Paleontology, Part P Arthropoda 2, Chelicerata'', pp. 36–37.
Classification
Kjellesvig-Waering (1966) concluded that "there is no other genus that warrants comparison, or, indeed at our present state of knowledge, reveals any close affinities with this very unusual genus", though the genus was able to be classified as astylonurine
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 ...
. In later years, further similarities have been noted between ''Brachyopterus'' and the rhenopterids. Lamsdell et al. (2010) classified it as the most basal of the rhenopterids and a sister taxon to more derived rhenopterids (such as ''Kiaeropterus
''Kiaeropterus'' is a genus of prehistoric eurypterid classified as part of the Rhenopteridae family. Two species, both from the Silurian period, are known; ''K. cyclophthalmus'' from Scotland and ''K. ruedemanni'' from Norway.Dunlop, J. A., P ...
'' and ''Rhenopterus
''Rhenopterus'' is an extinct prehistoric eurypterid. Fossils of ''Rhenopterus'' have been recovered from deposits of Lower Devonian age in Germany.Dunlop, J. A., Penney, D. & Jekel, D. 2015. A summary list of fossil spiders and their relatives. ...
'').
See also
*List of eurypterids
This list of eurypterid genera is a comprehensive listing of all genera that have ever been included in the order Eurypterida, excluding purely vernacular terms. The list includes all commonly accepted genera, but also genera that are now conside ...
References
{{Taxonbar, from=Q4953501 Ordovician eurypterids Rhenopteroidea Fossils of Great Britain Eurypterids of Europe Fossil taxa described in 1951