This timeline of eurypterid research is a chronologically ordered list of important fossil discoveries, controversies of interpretation, and taxonomic revisions of eurypterids, a group of extinct aquatic arthropods closely related to modern arachnids and horseshoe crabs that lived during the Paleozoic Era.

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 and a missing link between trilobites and branchiopods, the fossil became the type species of first ever eurypterid to be scientifically described, Eurypterus remipes, in 1825.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, possibly due to the catfish-like appearance of its carapace.

1820s

1825 James E. DeKay recognized the fossil described by Mitchill as an arthropod and named it Eurypterus remipes, the first eurypterid to be described scientifically. DeKay interpreted the animal as a crustacean and as the missing link between trilobites and branchiopods.

1830s

1831 John Scouler examines and figures fossil remains from Lower Carboniferous 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, believing the fossils to represent a large fish.

1840s

1843 Burmeister created the family Eurypteridae to contain Eurypterus.Burmeister, Hermann (1843). Die Organisation der Trilobiten aus ihren lebenden Verwandten entwickelt. Georg Reimer.

1844 Agassiz recognized Pterygotus as an arthropod after the discovery of more complete remains, he classified it as a crustacean of the Entomostraca subclass.

1849 Agassiz described the species Pterygotus anglicus.

1850s

1851 Hermann Jordan excavates the first fossils of the genus Adelophthalmus.

1852 John William Salter described the species Pterygotus problematicus.

1854 Jordan and Hermann von Meyer describe the new species and genus Adelophthalmus granosus.

1855 August Emanuel 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) 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 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 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 Eurypterida as the taxonomic unit it is seen as today.

1866 Woodward created the subclass Merostomata 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 and Amos Henry Worthen 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.Goldenberg, Friedrich (1873). Fauna Saraepontana Fossilis. Die fossilien Thiere aus der Steinkohlenformation von Saarbrücken. Chr. Möllinger Verlag.

1874 Samuel Almond Miller described the new genus and species Megalograptus welchi, mistakenly believing the fragmentary fossils to represent a graptolite.

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 John William Dawson 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 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. 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 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 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 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 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 described the new species Pterygotus rhenaniae, later designated as the type species of Jaekelopterus. Erwin H. Barbour described the new species Anthraconectes nebraskensis. The discovery helped reinforce the idea as Adelophthalmus (or Anthraconectes) as a freshwater animal.

1915