''Drepanopterus'' is an extinct genus of

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 ...

and the only member of the family Drepanopteridae within the

Mycteropoidea Mycteropoidea is an extinct superfamily of eurypterids, an extinct group of chelicerate arthropods commonly known as "sea scorpions". It is one of four superfamilies classified as part of the suborder Stylonurina. Mycteropoids have been recovere ...

superfamily. There are currently three species assigned to the genus. The genus has historically included more species, with nine species associated with the genus ''Drepanopterus'', however five of these have since been proven to be synonyms of pre-existing species, assigned to their own genera, or found to be based on insubstantial fossil data. The holotype of one species proved to be a lithic clast. ''Drepanopterus pentlandicus'' was first described 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 ...

strata 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 Pentlan ...

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 ...

. The only other fully described valid species is ''Drepanopterus abonensis'', from the Upper

Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, whe ...

Portishead, Somerset Portishead () is a coastal village on the Severn Estuary, 8 miles (12 km) to the west of Bristol, but within the unitary authority, unitary district of North Somerset, which falls within the Ceremonial counties of England, ceremonial county of So ...

. The exact relationship of ''Drepanopterus'' to other

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 ...

s has long been unclear, however it is now apparent that it is a primitive mycteropoid, and an early relative of the

Carboniferous The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago ( Mya), to the beginning of the Permian Period, million years ago. The name ''Carbonifero ...

Hibbertopterus ''Hibbertopterus'' is a genus of eurypterid, a group of extinct aquatic arthropods. Fossils of ''Hibbertopterus'' have been discovered in deposits ranging from the Devonian period in Belgium, Scotland and the United States to the Carboniferous ...

''.

Description

''Drepanopterus'' is distinguished by its "fairly large" size, compound eyes with parallel axes on a subrectangular to subovate prosoma (head). All of its legs are walking legs; the first three pairs are short and powerful, with spines; the last two pairs are moderately long, ending in strongly curved terminal claw. The last leg reaches as far as the penultimate abdominal segment. 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 ...

ranges from styliform to clavate. Drepanopterus date from the Silurian to the Upper Devonian periods.L. Størmer. 1955. Merostomata. ''Treatise on Invertebrate Paleontology, Part P Arthropoda 2, Chelicerata'', p. 36–37. Whilst classified as the basalmost member of the Drepanopteridae, ''Drepanopterus'' also shares certain characteristics with the kokomopteroids (such as having a clavate telson). ''Drepanopterus'' also has certain characteristics otherwise only found within the Mycteroptidae; appendage IV was not used in food capture and the coxae are large, as in ''

Megarachne ''Megarachne'' is a genus of eurypterid, an extinct group of aquatic arthropods. Fossils of ''Megarachne'' have been discovered in deposits of Late Carboniferous age, from the Gzhelian stage, in San Luis, Argentina. The fossils of the single and ...

''. Appendage III also retains some ''

Hughmilleria ''Hughmilleria'' is a genus of eurypterid, an extinct group of aquatic arthropods. Fossils of ''Hughmilleria'' have been discovered in deposits of the Silurian age in China and the United States. Classified as part of the basal family Hughmille ...

''-type conical spines suggesting that ''Drepanopterus'' hunted larger invertebrate or vertebrate prey than its later relatives.

Species

''Drepanopterus'' contains three valid species,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). with several others that historically have been assigned to it being recovered as outside of the genus. The species currently seen as valid species of the genus are: * ''Drepanopterus abonensis ''Simpson, 1951 — Devonian, England. * ''Drepanopterus odontospathus ''Lamsdell, 2012 — Devonian, Canada. * ''Drepanopterus pentlandicus ''Laurie, 1892 — Silurian, Scotland. Invalid or reassigned species are listed below: * "''Drepanopterus''" ''bembycoides'''' ''Laurie, 1899 — Silurian, Scotland. A basal member of the suborder

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 ...

. Potential synonym of '' Nanahughmilleria conica''. * "''Drepanopterus''" ''lobatus'''' ''Laurie, 1899 — Silurian, Scotland. Later recognised as a sexual dimorph of "''D''". ''bembycoides'', as it is identical except for the lobate epimera. * "''Drepanopterus''" ''longicaudatus'''' ''Clarke and Ruedemann, 1912 — Silurian, United States. Synonym of '' Kokomopterus''. * "''Drepanopterus''" ''nodosus'''' ''Kjellesvig-Waering and Leutze, 1966 — Silurian, United States. Undiagnostic holotype and paratype, a basal member of the suborder

. * "''Drepanopterus''" ''ruedemanni'''' '' O’Connell, 1916 — Ordovician, United States. A lithic clast. * "''Drepanopterus''" ''struvei'''' '' O’Connell, 1916 — Ordovician, United States. Synonym of '' Vinetopterus''.

References

{{Taxonbar, from=Q5306970 Stylonurina Fossils of Great Britain Devonian eurypterids Silurian eurypterids Eurypterids of Europe Silurian first appearances Eurypterids of North America

Description

Species

See also

References