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 preserved ...

discoveries, controversies of interpretation, and taxonomic revisions of

eurypterid Eurypterids, often informally called sea scorpions, are a group of extinct arthropods that form the order Eurypterida. The earliest known eurypterids date to the Darriwilian stage of the Ordovician period 467.3 million years ago. The group is l ...

s, a group of extinct aquatic

arthropod Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and cuticle made of chiti ...

s closely related to modern

arachnid Arachnida () is a class of joint-legged invertebrate animals (arthropods), in the subphylum Chelicerata. Arachnida includes, among others, spiders, scorpions, ticks, mites, pseudoscorpions, harvestmen, camel spiders, whip spiders and vinegar ...

s and

horseshoe crab Horseshoe crabs are marine and brackish water arthropods of the family Limulidae and the only living members of the order Xiphosura. Despite their name, they are not true crabs or crustaceans: they are chelicerates, most closely related to ar ...

s that lived during the

Paleozoic The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon. The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838 by combining the Greek words ''palaiós'' (, "old") and ' ...

Era An era is a span of time defined for the purposes of chronology or historiography, as in the regnal eras in the history of a given monarchy, a calendar era used for a given calendar, or the geological eras defined for the history of Earth. Comp ...

. 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 (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group can ...

and a missing link between

trilobite Trilobites (; meaning "three lobes") are extinct marine arthropods that form the class Trilobita. Trilobites form one of the earliest-known groups of arthropods. The first appearance of trilobites in the fossil record defines the base of the ...

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 a ...

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

Silurus ''Silurus'' is a genus of catfishes Catfish (or catfishes; order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior ...

'', possibly due to the

catfish Catfish (or catfishes; order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the three largest species alive ...

-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 (surname) *Lower Township, New Jersey *Lower Receiver (firearms) *Lower Wick Gloucestershire, England See also *Nizhny Nizhny (russian: Ни́жний; masculine), Nizhnyaya (; feminine), or Nizhneye (russian: Ни́� ...

Scotland which will later be referred to '' Hibbertopterus scouleri''. *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 described the new genus ''

Pterygotus ''Pterygotus'' is a 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 several ...

'', 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, Cepha ...

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 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 at Frankfurt am Ma ...

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

August Emanuel von Reuss August Emanuel Rudolph von Reuss (8 July 1811 in Bílina, Bohemia26 November 1873 in Vienna), Austrian geologist and palaeontologist, was the son of Franz Ambrosius Reuss (1761–1830) and the father of ophthalmologist August Leopold von Reuss ( ...

described the new species and genus ''Lepidoderma imhofi''. 1856 *Salter described the new genus '' Himantopterus'' (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''. *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''.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 specialising in comparative anatomy. He has become known as "Darwin's Bulldog" for his advocacy of Charles Darwin's theory of evolution. The stori ...

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'' 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 Scotti ...

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 arthropods that form the order Eurypterida. The earliest known eurypterids date to the Darriwilian stage of the Ordovician period 467.3 million years ago. The group is l ...

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

Merostomata Xiphosura () is an order of arthropods related to arachnids. They are more commonly known as horseshoe crabs (a name applied more specifically to the only extant family, Limulidae). They first appeared in the Hirnantian (Late Ordovician). Current ...

to contain eurypterids and xiphosurans. * Ernst Haeckel 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 bu ...

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 Ad ...

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. 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. alveolatu ...

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 geologist ...

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 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 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 marine and brackish chelicerate arthropod. Despite their name, horseshoe crabs are more closely related to spiders, ticks, and sco ...

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

20th century

1900s

1901 *

Charles Emerson Beecher Charles Emerson Beecher (October 9, 1856 – February 14, 1904) was an American paleontologist most famous for the thorough excavation, preparation and study of trilobite ventral anatomy from specimens collected at Beecher's Trilobite Bed. B ...

described the new genus and species '' Strabops thacheri'' 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 Neusalz (Nowa Sól), Prussian Silesia, the son of a builder and the youngest of seven children. He studied at ...

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

Jaekelopterus ''Jaekelopterus'' is a genus of predatory eurypterid, a group of extinct aquatic arthropods. Fossils of ''Jaekelopterus'' have been discovered in deposits of Early Devonian age, from the Pragian and Emsian stages. There are two known species: th ...

''. * 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 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, paleobotan ...

described the species ''Anthraconectes brasdorensis''. 1924 * Carl Owen Dunbar 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''. *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, 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 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 ...

'' 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 Nestor Ivanovich Novozhilov was a Soviet paleontologist. In 1948, Novozhilov described a pliosaur specimen discovered on the banks of Russia's Volga Riveras a new species, ''Pliosaurus rossicus''. The specimen, while large, was damaged during the e ...

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.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 tu ...

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 San Luis, Argentina. The fossils of the single and ...

'' as a

mygalomorph The Mygalomorphae, or mygalomorphs, are an infraorder of spiders, and comprise one of three major groups of living spiders with over 3000 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 sen ...

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 Chasmataspidida. Chasmataspidids are probably related to horseshoe crabs ( Xiphosura) and/or sea scorpions ( Eurypterida), wi ...

.''''

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 '' Ciurcopterus'' 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 ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical ...

. * 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'', 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