This timeline of eurypterid research is a chronologically ordered list of important

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

discoveries, controversies of interpretation, and

taxonomic 280px, Generalized scheme of taxonomy Taxonomy is a practice and science concerned with classification or categorization. Typically, there are two parts to it: the development of an underlying scheme of classes (a taxonomy) and the allocation ...

revisions of

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 ...

s, a group of extinct aquatic

arthropod Arthropods ( ) are invertebrates in the phylum Arthropoda. They possess an arthropod exoskeleton, exoskeleton with a cuticle made of chitin, often Mineralization (biology), mineralised with calcium carbonate, a body with differentiated (Metam ...

s closely related to modern

arachnid Arachnids are arthropods in the Class (biology), class Arachnida () of the subphylum Chelicerata. Arachnida includes, among others, spiders, scorpions, ticks, mites, pseudoscorpions, opiliones, harvestmen, Solifugae, camel spiders, Amblypygi, wh ...

s and

horseshoe crab Horseshoe crabs are arthropods of the family Limulidae and the only surviving xiphosurans. Despite their name, they are not true crabs or even crustaceans; they are chelicerates, more closely related to arachnids like spiders, ticks, and scor ...

s that lived during the

Paleozoic The Paleozoic ( , , ; or Palaeozoic) Era is the first of three Era (geology), geological eras of the Phanerozoic Eon. Beginning 538.8 million years ago (Ma), it succeeds the Neoproterozoic (the last era of the Proterozoic Eon) and ends 251.9 Ma a ...

Era An era is a span of time. Era or ERA may also refer to: * Era (geology), a subdivision of geologic time * Calendar era Education * Academy of European Law (German: '), an international law school * ERA School, in Melbourne, Australia * E ...

. The scientific study of eurypterids began in the early 19th century when James E. DeKay recognized a fossil that had previously been described as that of a fish as arthropod in nature. Though DeKay erroneously believed the fossil to represent a

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

and a missing link between

trilobite Trilobites (; meaning "three-lobed entities") are extinction, extinct marine arthropods that form the class (biology), class Trilobita. One of the earliest groups of arthropods to appear in the fossil record, trilobites were among the most succ ...

s and branchiopods, the fossil became the type species of first ever eurypterid to be scientifically described, ''

Eurypterus remipes ''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 ...

'', in

1825 Events January–March * January 4 – King Ferdinand I of the Two Sicilies dies in Naples and is succeeded by his son, Francis. * February 3 – Vendsyssel-Thy, once part of the Jutland peninsula forming westernmost Denmark, becomes an ...

.Clarke, J. K., Ruedemann R. (1912) " The Eurypterida of New York" Over 250 species of eurypterids in 74 recognized valid genera have been described since the discovery of ''Eurypterus remipes''. The most recent genus to be described is '' Terropterus'' (2021) and the most recent species is its type species ''Terropterus xiushanensis'' (2021).

19th century

1810s

1818 * The first eurypterid fossil to be discovered is unearthed in rocks in

New York New York most commonly refers to: * New York (state), a state in the northeastern United States * New York City, the most populous city in the United States, located in the state of New York New York may also refer to: Places United Kingdom * ...

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 ...

age. It is described by Dr. S. L. Mitchill as an example of the fish ''

Silurus ''Silurus'' is a genus of catfishes native to Europe and Asia. Species There are currently 20 recognized species in this genus: * '' Silurus aristotelis'' Garman, 1890 (Aristotle's catfish) * '' Silurus asotus'' Linnaeus, 1758 (Amur catfish) * ...

'', possibly due to the

catfish Catfish (or catfishes; order (biology), order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Catfish are common name, named for their prominent barbel (anatomy), barbels, which resemble a cat's whiskers, though not ...

-like appearance of its carapace.

1820s

1825 * James E. DeKay recognized the fossil described by Mitchill as an

and named it ''

'', the first eurypterid to be described scientifically. DeKay interpreted the animal as a

and as the missing link between

s and branchiopods.

1830s

1831 * John Scouler examines and figures fossil remains from

Lower Carboniferous Lower may refer to: * ''Lower'' (album), 2025 album by Benjamin Booker *Lower (surname) *Lower Township, New Jersey *Lower Receiver (firearms) *Lower Wick Lower Wick is a small hamlet located in the county of Gloucestershire, England. It is sit ...

Scotland which will later be referred to ''

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

''. *Scouler described the genus ''Eidothea'' based on a single fossil without designating a species name. 1836 * Samuel Hibbert describes the species ''Eurypterus scouleri'', later transferred to its own genus, ''Hibbertopterus''. *Scouler's ''Eidothea'' is discovered to be pre-occupied by a genus of plant, his fossil is found to be similar to ''Eurypterus scouleri''. 1838 * Stepan S. Kutorga described the species ''Limulus oculatus'' as an extinct horseshoe crab. 1839 *

Louis Agassiz Jean Louis Rodolphe Agassiz ( ; ) FRS (For) FRSE (May 28, 1807 – December 14, 1873) was a Swiss-born American biologist and geologist who is recognized as a scholar of Earth's natural history. Spending his early life in Switzerland, he recei ...

described the new genus ''

Pterygotus ''Pterygotus'' is an extinct genus of giant predatory eurypterid, a group of extinct aquatic arthropods. Fossils of ''Pterygotus'' have been discovered in deposits ranging in age from Middle Silurian to Late Devonian, and have been referred to s ...

'', believing the fossils to represent a large fish.

1840s

1843 * Burmeister created the family Eurypteridae to contain ''Eurypterus''. 1844 * Agassiz recognized ''Pterygotus'' as an arthropod after the discovery of more complete remains, he classified it as a

of the

Entomostraca Entomostraca is a historical subclass of crustaceans, no longer in technical use. It was originally considered one of the two major lineages of crustaceans (the other being the class Malacostraca), combining all other classes—Branchiopoda, Cep ...

subclass. 1849 * Agassiz described the species ''Pterygotus anglicus''.

1850s

1851 * Hermann Jordan excavates the first fossils of the genus ''

Adelophthalmus ''Adelophthalmus'' is a genus of eurypterid, an extinct group of aquatic arthropods. Fossils of ''Adelophthalmus'' have been discovered in deposits ranging in age from the Early Devonian to the Early Permian, which makes it the longest lived of ...

''. 1852 *

John William Salter John William Salter (15 December 1820 – 2 December 1869) was an English naturalist, geologist, and palaeontologist. Salter was apprenticed in 1835 to James De Carle Sowerby, and was engaged in drawing and engraving the plates for Sowerby' ...

described the species ''Pterygotus problematicus''. 1854 * Jordan and

Hermann von Meyer Christian Erich Hermann von Meyer (3 September 1801 – 2 April 1869), known as Hermann von Meyer, was a German palaeontologist. He was awarded the 1858 Wollaston medal by the Geological Society of London. Life He was born in Frankfurt am ...

describe the new species and genus '' Adelophthalmus granosus''. 1855 *

August Emanuel von Reuss August Emanuel Rudolph von Reuss (8 July 1811 – 26 November 1873) was an Austrian geologist and palaeontologist. Biography Reuss was born on 8 July 1811 in Bílina, Bohemia. He was the son of Franz Ambrosius Reuss (1761–1830) and the father ...

described the new species and genus ''Lepidoderma imhofi''. 1856 *Salter described the new genus ''

Himantopterus ''Himantopterus'' is a genus of moths in the family Himantopteridae. It was described by Constantin Wesmael in 1836. Species * '' Himantopterus caudata'' Moore, 1879 * ''Himantopterus dohertyi ''Himantopterus'' is a genus of moths in the family ...

'' (the genus name was replaced in 1859 by ''

Erettopterus ''Erettopterus'' is a genus of large predatory eurypterid, an extinct group of aquatic arthropods. Fossils of ''Erettopterus'' have been discovered in deposits ranging from Early Silurian (the Rhuddanian age) to the Early Devonian (the Lochkov ...

'') and the new species ''H. acuminatus'', ''H. banksii'', ''H. bilobus'', ''H. lanceolatus'', ''H. maximus'' and ''H. perornatus''. *Salter described the species ''Pterygotus acuminata''. *Page transferred ''Pterygotus acuminata'' to its own genus, ''

Slimonia ''Slimonia'' is a genus of eurypterid, an extinct group of aquatic arthropods. Fossils of ''Slimonia'' have been discovered in deposits of Silurian age in South America and Europe. Classified as part of the family Slimonidae alongside the relat ...

''. *Page named and figured, but did not thoroughly describe, the genus '' Stylonurus''. 1859 * Hall describes the species ''Pterygotus marcophthalmus''. It will later be considered part of the genus ''

Acutiramus ''Acutiramus'' is a genus of giant predatory eurypterid, an extinct group of aquatic arthropods. Fossils of ''Acutiramus'' have been discovered in deposits of Late Silurian to Early Devonian age. Eight species have been described, five from Nor ...

''.Clarke, J. K., Ruedemann R. (1912) " The Eurypterida of New York" * Hall describes the species ''Pterygotus osborni''. *Hall describes the species ''Pterygotus cobbi''. *Salter names a subgenus of ''Pterygotus'', ''Erettopterus'', for species with a bilobed telson. *Salter described the species ''Slimonia stylops''. *Salter described the species ''Eurypterus abbreviatus''. *Salter described the species ''Pterygotus ludensis''. *Salter described the species ''Pterygotus punctatus''. *Salter described the species ''Eurypterus pygmaeus'', later recognized as representing fossils of '' Nanahughmilleria''. *Salter and

Thomas Henry Huxley Thomas Henry Huxley (4 May 1825 – 29 June 1895) was an English biologist and anthropologist who specialized in comparative anatomy. He has become known as "Darwin's Bulldog" for his advocacy of Charles Darwin's theory of evolution. The stor ...

describe the fossil specimens that will later be named '' Necrogammarus salweyi'', believing them to represent some sort of crustacean.

1860s

1860 * Edouard D'Eichwald recognized Kutorga's ''Limulus oculatus'' to be highly distinct from ''Limulus'' and created the generic name ''

Campylocephalus ''Campylocephalus'' is a genus of eurypterid, a group of extinct aquatic arthropods. Fossils of ''Campylocephalus'' have been discovered in deposits ranging from the Carboniferous period in the Czech Republic (the species ''C. salmi'') to the Pe ...

'' to contain the species. 1861 *

John William Dawson Sir John William Dawson (1820–1899) was a Canadian geologist and university administrator. Life and work John William Dawson was born on 13 October 1820 in Pictou, Nova Scotia, where he attended and graduated from Pictou Academy. Of Sco ...

named a new species of plant, ''Selaginites formosus''. 1865 * Henry Woodward described the genus ''Stylonurus'' (named and figured, but not thoroughly described, by David Page in 1856) and raised the rank of the Eurypteridae to that of order, effectively creating the

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 ...

a as the taxonomic unit it is seen as today. 1866 *Woodward created the subclass

Merostomata Merostomata is a class of chelicerate arthropods that contains the extinct Eurypterida (sea scorpions) and the extant Xiphosura (horseshoe crabs). The term was originally used by James Dwight Dana to refer to Xiphosura only, but was emended by ...

to contain eurypterids and xiphosurans. *

Ernst Haeckel Ernst Heinrich Philipp August Haeckel (; ; 16 February 1834 – 9 August 1919) was a German zoologist, natural history, naturalist, eugenics, eugenicist, Philosophy, philosopher, physician, professor, marine biology, marine biologist and artist ...

classified the Merostomata (containing virtually only the Eurypterida) and Xiphosura within a group he named Gigantostraca within the crustaceans. "Gigantostraca" is later treated as a synonym of Mersostomata. 1868 * Salter described the species ''Pterygotus taurinus''. *Woodward described the species ''Eurypterus obesus''. *Woodward described the species ''Eurypterus scorpioides''. *

Fielding Bradford Meek Fielding Bradford Meek (December 10, 1817 – December 22, 1876) was an American geologist and a paleontologist who specialized in the invertebrates. Biography The son of a lawyer, he was born in Madison, Indiana. In early life he was in ...

and

Amos Henry Worthen Amos Henry Worthen (1813–1888) was an American geologist and paleontologist from Illinois. He was the second state geologist of Illinois and the first curator of the Illinois State Museum. He was a fellow of the American Association for the Adv ...

described the new species and genus ''Anthraconectes mazonensis''. ''Anthraconectes'' was designated a subgenus of ''Eurypterus''.

1870s

1870 * Henry Woodward described the species ''Necrogammarus salweyi'', believing it to represent an

amphipod Amphipoda () is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods () range in size from and are mostly detritivores or scavengers. There are more than 10,700 amphipod species cur ...

. 1871 * Dawson reclassified his plant ''Selaginites formosus'' as a eurypterid. 1872 * Barrande describes ''Pterygotus bohemicus'', later considered part of the genus ''Acutiramus'', ''P. kopaninensis'' and ''P. nobilis''. *Walcott described the genus and species ''Echinognathus clevelandi''. 1873 * Friedrich Goldenberg coined the name ''Polyzosternites'' to replace ''Adelophthalmus''. 1874 * Samuel Almond Miller described the new genus and species ''

Megalograptus ''Megalograptus'' is a genus of eurypterid, an extinct group of aquatic arthropods. Fossils of ''Megalograptus'' have been recovered in deposits of Katian (Late Ordovician) age in North America. The genus contains five species: ''M. alveolatus ...

welchi'', mistakenly believing the fragmentary fossils to represent a

graptolite Graptolites are a group of colonial animals, members of the subclass Graptolithina within the class Pterobranchia. These filter-feeding organisms are known chiefly from fossils found from the Middle Cambrian ( Miaolingian, Wuliuan) through t ...

. 1875 * Grote and Pitt describe ''Pterygotus cummingsi'', later considered the type species of ''Acutiramus''. *Grote and Pitt describe the species '' Eusarcus scorpionis''. 1877 * Dionýs Štúr described the species ''Eurypterus salmi'', later referred to ''Campylocephalus''. *Meek and Worthen described the species ''Eurypterus pennsylvanicus'', later referred to ''Adelophthalmus''. *Hall described the species ''Eurypterus mansfieldi'', later referred to ''Adelophthalmus''. 1879 *

described the species ''Erettopterus canadensis''.

1880s

1881 * Pohlman described the species ''Pterygotus buffaloensis''. It is later synonymized with ''P. cummingsi''. *Pohlman described the species ''Erettopterus grandis''. *The type and only known specimen of ''Tylopterella boylei'' (first named ''Eurypterus boylei'') is discovered. 1882 *

Ben Peach Benjamin Neeve Peach (6 September 1842 – 29 January 1926) was a British geologist. Life Peach was born at Gorran Haven in Cornwall on 6 September 1842 to Jemima Mabson and Charles William Peach, an amateur British naturalist and geologis ...

named the genus ''Glyptoscorpius'' to include some fossils from the Carboniferous of Scotland, including the species ''G. perornatus'', ''G. caledonicus'' and ''G. kidstoni''. He mistakenly believed the fossils to represent the remains of scorpions. 1883 * Carl Friedrich Schmidt described the species ''Erettopterus osiliensis''.Schmidt, Friedrich (1883)
Die Crustaceenfauna der Eurypterenschichten von Rootziküll auf Oesel
1884 * The holotype and only known specimen of '' Vernonopterus minutisculptus'' is discovered. *

Joseph Frederick Whiteaves Joseph Frederick Whiteaves (December 26, 1835 – August 8, 1909), was a British palaeontologist. Born in Oxford, Whiteaves was educated at private schools, and afterwards worked under John Phillips at Oxford (1858–1861); he was led to st ...

described the species ''Eurypterus boylei''. *Hall described the species ''Eurypterus prominens''. 1888 * Hall and Clarke described the species ''Eurypterus approximatus'', later referred to ''Adelophthalmus''. * Woodward described the species ''Eurypterus wilsoni'', later referred to ''Adelophthalmus''. 1889 *Matthew described the new genus and species '' Bunodella horrida'' as a crustacean. *Dewalque described the species ''Eurypterus lohesti''.

1890s

1890 * Edward Waller Claypole described the genus and species ''Eurysoma newlini''. Later that same year he discovered ''Eurysoma'' to be pre-occupied, and coined the replacement name ''

Carcinosoma ''Carcinosoma'' (meaning "crab body") is a genus of eurypterid, an extinct group of aquatic arthropods. Fossils of ''Carcinosoma'' are restricted to deposits of late Silurian (Late Llandovery to Early Pridoli) age. Classified as part of the fam ...

''. *Pereira de Lima described the species ''Eurypterus douvillei'', later referred to ''Adelophthalmus''. 1893 * In the work ''Anatomy and Relations of the Eurypterida'' (1893),

Malcolm Laurie Malcolm Laurie FRSE FLS (27 February 1866 – 16 July 1932) was a Scottish zoologist and palaeontologist. Biography He was born in Brunstane House south of Portobello, Edinburgh on 27 February 1866, the son of Catherine Ann Hibburd and h ...

added considerably to the knowledge and discussion of eurypterid anatomy and relations. He focused on how the eurypterids related to each other and to trilobites, crustaceans, scorpions, other arachnids and horseshoe crabs. 1896 *Gerhard Holm described the species ''Eurypterus fischeri''. His description was so elaborate that the species became one of the most completely known of all extinct animals, so much so that the knowledge of ''E. fischeri'' was comparable with the knowledge of its modern relatives (such as the

Atlantic horseshoe crab The Atlantic horseshoe crab (''Limulus polyphemus''), also known as the American horseshoe crab, is a species of horseshoe crab, a kind of marine biology, marine and Brackish water, brackish chelicerate arthropod. It is found in the Gulf of Mexic ...

). The description also helped solidify the close relationship between the eurypterids and other chelicerates by showcasing numerous homologies between the two groups. *Samuel Almond Miller and William Frank Eugene Gurley described the species ''Eurypterus kokomoensis'', later considered the type species of the genus '' Onychopterella''. 1898 * Semper described the species ''Pterygotus barrandei'' and ''Eurypterus acrocephalus''. 1899 * Laurie described the species ''Slimonia dubia''. *Laurie described the species ''Eurypterus scoticus''. *McCoy described the species ''Pterygotus australis'', the first eurypterid known from

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

. *Fraipont described the species ''Eurypterus dewalquei''.

20th century

1900s

1901 * Charles Emerson Beecher described the new genus and species ''

Strabops thacheri ''Strabops'' is a genus of strabopid, an extinct group of arthropods. ''Strabops'' is known from a single specimen from the Late Cambrian (Furongian age) of the Potosi Dolomite, Missouri, collected by a former professor, Arthur Thacher. It is ...

'' as the only Cambrian eurypterid. 1902 * Sarle described the species ''Pterygotus monroensis''. 1903 *Clifton J. Sarle described the new species ''Pterygotus monroensis'' and ''Eurypterus pittsfordensis''. The new genus and species '' Hughmilleria socialis'' with the variety ''H. socialis'' var. ''robusta'' is also described. 1905 * Peach described the new species ''Glyptoscorpius minutisculptus''. 1907 *

John Mason Clarke John Mason Clarke (April 15, 1857 – May 29, 1925) was an American teacher, geologist and paleontologist. __TOC__ Early career Born in Canandaigua, New York, the fifth of six children of Noah Turner Clarke and Laura Mason Merrill, he attended ...

described the new species ''Pterygotus otisius'', ''Hughmilleria shawangunk'', ''Eurypterus maria'', ''E. myops'', ''E. cicerops'' and ''E. cestrotus''. *Woodward described the species ''Eurypterus moyseyi'', later referred to ''Adelophthalmus''. 1908 * Ruedemann recognizes that ''Megalograptus'' is an eurypterid, rather than a graptolite.

1910s

1911 *

Johan Aschehoug Kiær Johan Aschehoug Kiær (October 11, 1869 – October 31, 1931) was a Norwegian paleontologist and geologist. Biography Johan Kiær was born in Drammen, Norway. He was the son of parish priest Hagbarth Kiær (1829–1903) and grandson of shipown ...

described the species ''Eurypterus norvegica''. 1912 * Ruedemann and Clarke publish ''The Eurypterida of New York'', wherein several new speciesand taxonomic groupings are created. New species described are ''Eurypterus megalops'', ''Eurypterus pristinus'', ''Eurypterus ranilarva'', ''Eurypterus stellatus'', ''Eusarcus longiceps'', ''Eusarcus triangulatus'', ''Eusarcus vaningeni'', ''Dolichopterus frankfortensis'', ''Dolichopterus latifrons'', ''Dolichopterus siluriceps'', ''Dolichopterus testudineus'', ''Dolichopterus stylonuroides'', ''Stylonurus limbatus'', ''Ctenopterus multispinosus'', ''Drepanopterus longicaudatus'', ''Hughmilleria magna'', ''Pterygotus atlanticus'', ''Erettopterus globiceps'', ''Pterygotus nasatus'' and ''Pterygotus prolificus''. They also name the genus ''Tylopterus'' (later '' Tylopterella'') and the family Pterygotidae. There are also numerous taxonomic revisions. ''Eurypterus obesus'' and ''E. acrocephalus'' are referred to the genus ''Eusarcus''. The genus ''Carcinosoma'', to which the species ''Eurypterus scorpioides'' and ''Eurypterus scoticus'' are transferred, is designated as a junior synonym of ''Eusarcus''. The species ''Eurypterus kokomoensis'' is raised to the subgeneric level under the subgenus name ''Onychopterus''. 1914 *

Otto Jaekel Otto Max Johannes Jaekel (21 February 1863 – 6 March 1929) was a German paleontologist and geologist. Biography Jaekel was born in Nowa Sól, Neusalz (Nowa Sól), Prussian Silesia, the son of a builder and the youngest of seven children. He st ...

described the new species ''Pterygotus rhenaniae'', later designated as the type species of ''

Jaekelopterus ''Jaekelopterus'' is a genus of predatory 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 ...

''. * Erwin H. Barbour described the new species ''Anthraconectes nebraskensis''. The discovery helped reinforce the idea as ''Adelophthalmus'' (or ''Anthraconectes'') as a freshwater animal. 1915 * Xavier Stainier described the species ''Eurypterus dumonti'', later referred to ''Adelophthalmus''. *Ellis W. Shuler described the species ''Stylonurus'' (''Ctenopterus'') ''alveolatus'', later referred to ''Megalograptus''. 1916 *Thomas Edmund Savage described the species ''Eurypterus pumilus''.

1920s

1920 *

Amadeus William Grabau Amadeus William Grabau (January 9, 1870 – March 20, 1946) was an American geologist, teacher, stratigrapher, paleontologist, and author who worked in the United States and China. Biography Grabau's grandfather, J.A.A. Grabau, led a group of ...

described the species ''Anthraconectes chinensis''. 1921 * Ruedemann described the new species ''Pterygotus vernonensis''. *Ruedemann described the species ''Hughmilleria phelpsae'', later designated as the type species of '' Pittsfordipterus''. 1922 *

Walter A. Bell Walter Andrew Bell (January 4, 1889 – 1969) was a Canadian geologist. He worked for the Geological Survey of Canada for over 40 years and authored or co-authored 70 publications. Most of them concerning Carboniferous stratigraphy, paleobotany a ...

described the species ''Anthraconectes brasdorensis''. 1924 *

Carl Owen Dunbar Carl Owen Dunbar (January 1, 1891 – April 7, 1979) was an American paleontologist who specialized in invertebrate fossils. He was a Professor of Geology at Yale University from 1920 until 1959. He was also Director of the Peabody Museum of Natu ...

described the species ''Anthraconectes sellardsi''. 1926 *

Embrik Strand Embrik Strand (2 June 1876 – 3 November 1947) was an entomologist and arachnologist who classified many insect and spider species, including the greenbottle blue tarantula. Life and career Strand was born in Ål, Norway. He studied at t ...

described the species ''Pterygotus siemiradzkii''.

1930s

1933 * Boris Isidorovich Chernyshev described the species ''Eurypterus carbonarius'', later referred to ''Adelophthalmus''. 1934 * ''Eusarcus'' is recognized as a pre-occupied name by Størmer, who transfers its species to the next oldest available name, ''Carcinosoma''. *Størmer describes the species ''Hughmilleria patteni''. 1935 * Ruedemann names new subgenera of ''Pterygotus'': ''Curviramus'' and ''Acutiramus''. They are differentiated by the curvature of denticles in their chelicerae. 1936 * Størmer provides a more comprehensive and detailed description of ''Pterygotus rhenaniae''. *Etheridge, Jr. described the species ''Glyptoscorpius stevensoni''. 1938 * Carl E. Decker described the species ''Anthraconectes oklahomensis''. 1939 *Gilbert Oscar Raasch referred ''Strabops'' to the order Aglaspida. *Roy Woodhouse Pocock and A. J. Butler discover a relatively complete telson of ''Eurypterus abbreviatus'', showing that the species was highly distinct from other species referred to the genus. *Pruvost described the species ''Anthraconectes corneti''.

1940s

Unionopterus anastasiae carapace restoration

1942 * Strand proposes the replacement name ''

Eusarcana ''Eusarcana'' (meaning "true flesh") is a genus of eurypterid, an extinct group of aquatic arthropods. Fossils of ''Eusarcana'' have been discovered in deposits ranging in age from the Early Silurian to the Early Devonian. Classified as part of ...

'' for ''Eusarcus'' but it is ignored since ''Carcinosoma'' is already in use as the replacement name. 1948 * Kjellesvig-Waering described the new species ''Pterygotus ventricosus'', later considered the type species of ''

Ciurcopterus ''Ciurcopterus'' is a genus of eurypterid, an extinct group of aquatic arthropods. Fossils of ''Ciurcopterus'' have been discovered in deposits of Late Silurian age in North America. Formerly classified as part of the family Pterygotidae, but pl ...

''. *Kjellesvig-Waering raised the subgenus ''Onychopterus'' to the rank of a separate genus. He also assigned the species ''Eurypterus pumilus'' to the genus. *Boris Isidorovich Chernyshev described the new species '' Unionopterus anastasiae''.

1950s

1950 *Kjellesvig-Waering described the new species ''Hughmilleria bellistriata''. *Kjellesvig-Waering described the new species ''Pterygotus floridanus''. 1951 *Kjellesvig-Waering described the new family

Hughmilleriidae Hughmilleriidae (the name deriving from the type genus ''Hughmilleria'', which is named in honor of Scottish geologist Hugh Miller) is a family of eurypterids, an extinct group of aquatic arthropods. The hughmilleriids were the most basal member ...

, composed of ''Hughmilleria'', ''Slimonia'', ''Grossopterus'', ''Lepidoderma'', ''Hastimima'' and the new genus '' Salteropterus abbreviatus'' (formerly a species of ''Eurypterus''), leaving the Pterygotidae monotypic. *Størmer concluded that ''Campylocephalus'' and ''Hibbertopterus'' were congeneric. The fossils that had been referred to ''Ediothea'' were recognized as representatives of ''Campylocephalus''. *Størmer noted that the name ''Onychopterus'' was pre-occupied and coined the replacement name '' Onychopterella''. *Kjellesvig-Waering coined the replacement name '' Tylopterella'' for the genus ''Tylopterus'', as the name ''Tylopterus'' was found to be preoccupied. *Augusta and Pribyl described the species ''Ctenopterus ostraviensis''. 1952 * Přibyl described the species ''Anthraconectes zadrai''. 1953 * Russell described the new species ''Pterygotus gaspesiensis''. 1955 * Kjellesvig-Waering describes the new genus and species '' Dorfopterus angusticollis'' as part of Stylonuridae. * Kjellesvig-Waering and Caster describe the species ''Acutiramus floweri''. * Kjellesvig-Waering describes the species ''Acutiramus suwanneensis''. *Kjellesvig-Waering and Caster revise the genus ''Megalograptus'' after more complete fossils are recovered of a new species, ''M. ohioensis''. Carcinosoma_newlini

1956 * Fredrik Herman van Oyen designate ''Anthraconectes'', ''Glyptoscorpius'', ''Lepidoderma'' and ''Polyzosternites'' as junior synonyms of ''Adelophthalmus''. 1957 *Pirozhnikov described two new species, ''Rhenopterus matarakensis'' and ''R. schiraensis''. *Kjellesvig-Waering and Størmer describe the new species ''Pterygotus howelli'', which would later be assigned to ''Jaekelopterus''. *Waterston gives a more complete description of ''Glyptoscorpius minutisculptus'' and refers it to ''Eurypterus'' as ''Eurypterus minutisculptus''. 1958 *Kjellesvig-Waering reaffirmed the status of ''Tylopterella'' as a separate genus from ''Eurypterus''. *Kjellesvig-Waering publishes a study which determines the coloration of ''Carcinosoma newlini''; showing that it was light brown with darker scales and appendages and a black telson and spines. 1959 * Kjellesvig-Waering recognized ''Campylocephalus'' as being distinct from ''Eurypterus scouleri'' and erected the genus ''

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

'' to contain ''E. scouleri''. *''Adelophthalmus oklahomensis'' is designated a junior synonym of ''Adelophthalmus sellardsi''.

1960s

1961 *Kjellesvig-Waering described the new species ''Salteropterus longilabium'', ''Pterygotus'' (''Pterygotus'') ''denticulatus'', ''P.'' (''P.'') ''grandidentatus'', ''P.'' (''P.'') ''lightbodyi'', ''Carcinosoma harleyi'' and ''Dolichopterus bulbosus''. The new genus '' Parahughmilleria'' is described with ''P. salteri'' as the type species. ''Hughmilleria bellistriata'', ''H. phelpsae'' and ''Eurypterus maria'' are moved to this genus. The subgenus ''Erettopterus'' is regarded as a new genus and is separated into two new subgenera, ''E.'' (''Erettopterus''), including the new species ''E.'' (''E.'') ''brodiei'', ''E.'' (''E.'') ''marstoni'' and ''E.'' (''E.'') ''spatulatus'', and ''E.'' (''Truncatiramus''), including the new subspecies ''E.'' (''T.'') ''gigas megalodon''. The genus ''Hughmilleria'' is split into two new subgenera, ''H.'' (''Hughmilleria'') and ''H.'' ('' Nanahughmilleria''). *Kjellesvig-Waering transfers the species ''Pterygotus punctatus'' to ''Carcinosoma'' as ''Pterygotus punctatum''. 1962 * Nestor Ivanovich Novozhilov names the genus ''Rhinocarcinosoma'' to contain the species ''R. vaningeni'' and ''R. cicerops'', previously referred to ''Eusarcus'' (''Paracacinosoma'').'''' 1964 * Charles D. Waterston names the genus ''Jaekelopterus'' to contain the species ''Pterygotus rhenaniae''. *Kjellesvig-Waering described the species ''Pterygotus impacatus'' and ''Pterygotus lanarkensis''. *Kjellesvig-Waering described the species ''Pterygotus marylandicus''. *Kjellesvig-Waering questionably assigned ''Selaginites formosus'' to ''Pterygotus'' as ''Pterygotus formosus''. *Caster and Khellesvig-Waering recognize ''Eusarcus'' and ''Carcinosoma'' to represent distinct genera and since ''Eusarcus'' is pre-occupied, they coin the replacement name ''Paracarcinosoma'' for its species. *Caster and Kjellesvig-Waering described the species ''Eocarcinosoma batrachophthalmus''. *Caster and Kjellesvig-Waering describe two new species of ''Megalograptus'', ''M. williamsae'' and ''M. shideleri''. They also assign the species ''M. alveolatus'', named as a species of ''Ctenpterus'', to ''Megalograptus''. 1966 *Kjellesvig-Waering and Willard P. Leutze described the new species '' Bassipterus virginicus'' (a new genus), ''Drepanopterus nodosus'' and ''Erettopterus'' (''Truncatiramus'') ''exophthalmus''. The species ''H.'' (''N.'') ''phelpsae'' is classified as a new genus, '' Pittsfordipterus''. ''Rhenopterus matarakensis'' is assigned to ''Parahughmilleria'', ''R. schiraensis'' is assigned to ''Hughmilleria'' (''Nanahughmilleria''). 1968 *Nestor Ivanovich Novojilov classifies ''Slimonia'' into a new family of its own, the

Slimonidae Slimonidae (the name deriving from the type genus ''Slimonia'', which is named in honor of Welsh fossil collector and surgeon Robert Slimon) is a family of eurypterids, an extinct group of aquatic arthropods. Slimonids were members of the super ...

.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). *Waterston re-examines ''Eurypterus minutisculptus'' and concludes that it represents a genus of its own, which he names '' Vernonopterus''. *Størmer and Waterston re-examine the fossil species referred to ''Glyptoscorpius'' and name the new genus ''Cyrtoctenus'', containing the species ''C. caledonicus'', ''C. dewalquei'' (previously ''Eurypterus''), ''C. ostraviensis'' (previously ''Ctenopterus'') and ''C. peachi.'' They also name the genus ''Dunsopterus'' to contain the species ''G. stevensoni''. 1969 *Størmer described the species ''Rhenopterus sievertsi''.

1970s

1971 * Kjellesvig-Waering described the species ''Erettopterus serricaudatus'' and ''Erettopterus carinatus''. *Bermudo Meléndez described the species ''Lepidoderma asturica''. 1973 * Kjellesvig-Waering described the species ''Slimonia boliviana''. 1974 * Størmer creates the family Jaekelopteridae to contain ''Jaekelopterus''. This family has subsequently been treated as synonymous with the Pterygotidae. *Størmer raises the ''Pterygotus'' subgenus ''Acutiramus'' and the ''Erettopterus'' subgenus ''Truncatiramus'' to the level of separate genera. 1979 * Kjellesvig-Waering described the new genus and species '' Holmipterus suecicus''. * Waterston creates the family

Parastylonuridae The Parastylonuridae are a family of eurypterids, an extinct group of chelicerate arthropods commonly known as "sea scorpions". The family is one of two families contained in the superfamily Stylonuroidea (along with Stylonuridae), which in turn ...

and includes ''Hardieopterus'', ''Parastylonurus'' and, tentatively, ''Dorfopterus'' and ''Lamontopterus'' on it.

1980s

1980 *Mario Hünicken described the new genus and species ''

Megarachne servinei ''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 the Bajo de Véliz Formation of San Luis, Argenti ...

'' as a

mygalomorph The Mygalomorphae, or mygalomorphs, are an infraorder of spiders, and comprise one of three major groups of living spiders with over 3,000 species, found on all continents except Antarctica. Many members are known as trapdoor spiders due to t ...

spider. 1981 * Barry S. Kues and Kenneth K. Kietzke described the species ''Adelophthalmus luceroensis''. 1983 * Roy E. Plotnick reassigns the species ''Eurypterus lohesti'' to ''Adelophthalmus'' and renders ''Dorfopterus'' an ''incertae sedis'' genus within Eurypterida. 1985 * John E. Almond examined the ''Necrogammarus'' fossil, believing it to represent an early aquatic relative of the

Uniramia Uniramia (''uni'' – one, ''ramus'' – branch, i.e. single-branches) is a group within the arthropods. In the past this group included the Onychophora, which are now considered a separate category. The group is currently used in a narrower sens ...

subphylum of arthropods. *Alexey G. Ponomarenko described the species ''Hibbertopterus permianus'', the last known surviving eurypterid. *Waterston, Oelofsen and Oosthuizen describe ''Cyrtoctenus wittebergensis''. *Jones and Kjellesvig-Waering publish a study on eurypterids from Arctic Canada. 1986 *Paul Selden recognizes the fossil remains of ''Necrogammarus'', previously believed to possibly represent a crustacean or a millipede, to be fragmentary fossils of a pterygotid eurypterid. 1989 *''Salteropterus'' is placed in the family Slimonidae by Tollerton. *Tollerton publishes a major taxonomic revision of the Eurypterida, dividing it into suborders Eurypterina and Ptergotina and recognizing some eurypterids, such as the hibbertopterids, as outside the order and part of a distinct order he calls Cyrtoctenida. Modern research favors suborders Eurypterina and Stylonurina instead. *The fossil that will later be designated as the holotype of ''Rhinocarcinosoma dosonensis'' is discovered in northern Vietnam and initially misidentified as a

chasmataspidid Chasmataspidids, sometime referred to as chasmataspids, are a group of extinct chelicerate arthropods that form the Order (biology), order Chasmataspidida. Chasmataspidids are probably related to horseshoe crabs (Xiphosura) and/or sea scorpions (E ...

.''''

1990s

1992 * Ciurca reported specimens of ''Rhinocarcinosoma'' and ''Paracarcinosoma'' from elsewhere in the United States, the genera previously mainly being known from fossils found in New York State. 1993 * Further fossils of ''Rhinocarcinosoma'' are collected in northern Vietnam which will later form the basis of the new species ''R. dosonensis''.'''' 1994 * Chlupáč describes the species ''Acutiramus perneri''. 1995 *Braddy, Richard John Aldridge and Johannes N. Theron described the species ''Onychopterella augusti''.

21st century

2000s

2002 * Braddy, Selden and Truong described the species ''Rhinocarcinosoma dosonensis''.'''' 2003 * Tollerton revises the Ordovician eurypterid genera of New York, determining that many of them are based on pseudofossils and thus invalid. 2004 * Poschmann reassigned the species ''Rhenopterus sievertsi'' to ''Adelophthalmus''. 2005 *Selden, Corronca and Hünicken recognized ''Megarachne servinei'' as a mycteroptid eurypterid. 2006 *Tetlie interpreted ''Hughmilleria banksii'' as a new genus, '' Herefordopterus''. In addition, the species ''Hughmilleria acuminata'' was synonymized with ''Herefordopterus banksii''. *Evgenyi S. Shpinev described the species ''Adelophthalmus irinae''. 2007 *Tetlie, Selden & Ren described the new species ''Hughmilleria wangi''. *Miller and Tetlie determine that ''Bunodella'' represents an indeterminate species of ''Acutiramus''. However, it is not formally synonymized and is regarded as a ''nomen dubium''. *Poschmann and Tetlie determine that ''Jaekelopterus'' was a highly derived pterygotid, not a basal form as previously assumed. It is declared to represent the largest known eurypterid. *Tetlie described the new species ''Pterygotus sarlei''. *Ciurca and Tetlie transfer the species ''Pterygotus waylandsmithi'' to ''Erettopterus''. Additionally, they concluded that ''P. monroensis'' was synonymous with ''E. osiliensis''. *Tetlie suggests that ''Dorfopterus'' might represent a telson of ''Strobilopterus princetonii'' and tentatively synonymizes ''Dorfopterus'' into the species. 2008 * Tetlie and Poschmann reclassify ''Hughmilleria patteni'' as part of its own genus, '' Eysyslopterus''. 2009 *Tetlie and Briggs erect the new genus ''

'' to contain species ''Pterygotus ventricosus'' and ''Pterygotus sarlei''.

2010s

2012 *Shpinev described the new species ''Parahughmilleria longa'' and ''Nanahughmilleria notosibirica''. *Shpinev described the new species ''Adelophthalmus kamyshtensis'' and ''Adelophthalmus dubius''. *Lamsdell publishes a phylogenetic analysis which finds Merostomata to be invalid, as Xiphosura is paraphyletic, and finds eurypterids to be more closely related to

s than to horseshoe crabs. *Jason A. Dunlop and Lamsdell pointed out that ''Eusarcana'' holds priority over ''Paracarcinosoma'' as a replacement name for ''Eusarcus'', designating ''Paracarcinosoma'' as a junior synonym of ''Eusarcana''. *Lamsdell reassigned ''Hibbertopterus permianus'' to ''Campylocephalus'' as ''Campylocephalus permianus''. 2013 * Lamsdell, Simonetto and Selden described the species ''Adelophthalmus piussii'', the first eurypterid to be discovered in

Italy Italy, officially the Italian Republic, is a country in Southern Europe, Southern and Western Europe, Western Europe. It consists of Italian Peninsula, a peninsula that extends into the Mediterranean Sea, with the Alps on its northern land b ...

. * Tetlie's suggestion that ''Dorfopterus'' is a telson of ''Strobilopterus princetonii'' is put into question by Lamsdell and Selden. 2015 *Poschmann transferred ''Erieopterus statzi'' to the genus ''Parahughmilleria''. The new genus and species '' Wiedopterus noctua'' is described. *Lamsdell ''et al.'' described the new genus and species ''

Pentecopterus decorahensis ''Pentecopterus'' is a genus of eurypterid, an extinct group of aquatic arthropods. Fossils have been registered from the Darriwilian age of the Middle Ordovician period, as early as 467.3 million years ago. The genus contains only one species, ...

'', the oldest eurypterid known to date. *McCoy, Lamsdell, Poschmann, Anderson and Briggs conduct a study on the eyes of pterygotid eurypterids and determine that the genera included in the family, such as ''Jaekelopterus'', ''Acutiramus'' and ''Ptergyotus'', had divergent adaptations, suggesting they had different ecological roles despite their close outward resemblance. 2017 *Vrazo & Ciurca described the new ichnogenus and ichnospecies '' Arcuites bertiensis'', interpreted as traces of a swimming eurypterid. 2018 *Plax ''et al.'' described the new genus and species '' Soligorskopterus tchepeliensis''. *Shpinev & Filimonov described the new species ''Adelophthalmus khakassicus''. 2019 *Emily Hughes concludes that the genera ''Cyrtoctenus'' and ''Dunsopterus'' represent junior synonyms of ''Hibbertopterus''.Hughes, Emily Samantha (2019),
Discerning the Diets of Sweep-Feeding Eurypterids Through Analyses of Mesh-Modified Appendage Armature
. ''Graduate Theses, Dissertations, and Problem Reports''. 3890. *Schoenemann, Poschmann and Clarkson publish a study comparing the eyes of ''Jaekelopterus'' with those of horseshoe crabs, arachnids and other arthropods. *Naugolnykh and Areshin describe the new species ''Soligorskopterus shpinevi''.

2020s

2020 *Russell D. C. Bicknell, Patrick M. Smith and Poschmann classify the species ''Pterygotus australis'' as a ''nomen dubium''. *Poschmann describes the new genus and species '' Pruemopterus salgadoi''. *Lamsdell ''et al.'' describe the new species ''Adelophthalmus pyrrhae''. 2021 *Brandt publishes a study on the possible relationships between eurypterid morphology, the ease with which members of this group experienced ecdysis and the longevity of eurypterid species. *Wang ''et al.'' describe '' Terropterus xiushanensis'', to date the most recently described eurypterid genus and species.

References

External links

* {{Eurypterida

Eurypterida