Pterygotioidea

Pterygotioidea; Temporal range: Early Silurian – Late Devonian, 442–372.2 Ma PreꞒ Ꞓ O S D C P T J K Pg N
	Fossil of Slimonia acuminata housed at the Senckenberg Museum of Frankfurt
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Chelicerata
Order:	† Eurypterida
Infraorder:	† Diploperculata
Superfamily:	† Pterygotioidea ; Clarke & Ruedemann, 1912
Type species
	† Pterygotus anglicus ; Agassiz, 1844
Families
	†Hughmilleriidae ; †Slimonidae ; †Pterygotidae ;
Synonyms
	Slimonioidea Novojilov, 1962; Hughmillerioidea Størmer, 1974;

Last updated January 24, 2024

Pterygotioidea (the name deriving from the type genus Pterygotus , meaning "winged one") is a superfamily of eurypterids, an extinct group of aquatic arthropods. Pterygotioids were the most derived members of the infraorder Diploperculata and the sister group of the adelophthalmoid eurypterids. The group includes the basal and small hughmilleriids, the larger and specialized slimonids and the famous pterygotids which were equipped with robust and powerful cheliceral claws.

Though the more primitive hughmilleriids were small, Hughmilleria wangi being the smallest of all pterygotioids at just 6 centimetres (2.4 in) in length, later members of the group, particularly in the Pterygotidae, would become the largest known arthropods to ever exist with several genera surpassing 2 metres (6.6 ft) in length.

Among all currently recognized eurypterid clades, the Pterygotioidea is the most diverse, containing over 50 species in 10 genera. With the number of recognized eurypterid species being around 250, pterygotioids account for more than a fifth of all known eurypterid species. Though the group only existed for around 70 million years and during a time when most continents were separated by large expanses of water (in contrast with previous and later periods of time when there had been supercontinents), the Pterygotioidea had the most cosmopolitan distribution of all eurypterid groups. Their fossils have been recovered from Europe, Africa, North America, South America, Asia and Australia, with the earliest remains being from the Early Silurian of Scotland and South China. The exact geographical origin of the group remains unknown, but is thought to have been in Laurentia.

Though several characteristic and diagnostic traits can be established for each of the families included within the Pterygotioidea, the group as a whole is primarily joined by the shared features of marginal eyes, that their compound eyes are placed near or on the margin of the carapace (the "head" plate).

Description

Restorations of slimonid Slimonia (top) and derived pterygotid Pterygotus (bottom).

Pterygotioid eurypterids, whose fossils are recovered in deposits ranging in age from the Early Silurian ^[1] to the Late Devonian,^[2] can be distinguished from all other eurypterine eurypterids by the placement of their eyes, being located near or in some cases on the margin of the carapace (the "head" plate).^[1] Pterygotioids ranged in size from small eurypterids, the smallest being Hughmilleria wangi at just 6 centimetres (2.4 in) in length, to the largest arthropods to ever live, the largest being Jaekelopterus rhenaniae which might have reached lengths of 2.6 metres (8.5 ft).^[3]^[4]

Like all other chelicerates, and other arthropods in general, pterygotioid eurypterids possessed segmented bodies and jointed appendages (limbs) covered in a cuticle composed of proteins and chitin. In the Pterygotidae, the outer surface of the exoskeleton was covered in a scale-like ornamentation but it was smooth within Slimonidae and Hughmilleriidae.^[5]

The chelicerate body is divided into two tagmata (sections); the frontal prosoma (head) and posterior opisthosoma (abdomen). The appendages were attached to the prosoma, and were characterized in pterygotids and slimonids by being small and slender and lacking spines.^[5] In contrast, the more basal Hughmilleriids did possess spines on their appendages.^[6]

In derived members of the group, Slimonidae and Pterygotidae, the telson (the posteriormost segment of the body) was expanded and flattened, often with a spike protruding from its end.^[7] The telsons of the Hughmilleriidae were not flattened, instead being lanceolate (in the shape of a lance or spike) and similar to those of more primitive eurypterids such as Eurypterus .^[8]

Like other chelicerates, pterygotioids possessed chelicerae. These appendages are the only ones that appear before the mouth and take the form of small pincers used to feed in most eurypterid groups. This function is retained in the more basal Hughmilleriidae and Slimonidae, but pterygotid chelicerae were large and long with strong and well developed teeth on specialized chelae (claws).^[1]

History of research

The first pterygotioid fossils to be uncovered were those of the type genus, Pterygotus. Louis Agassiz, a Swiss-American biologist and geologist, described the fossils in 1839 and named the genus Pterygotus, meaning "winged one". Agassiz mistakenly believed that the fossils were the remains of a large fish.^[9] Agassiz first recognized the true nature of the fossils as arthropod remains five years later in 1844 after having examined more complete fossils recovered in the Old Red Sandstone of Scotland.^[10]^[11]

In 1856, the species Pterygotus acuminata was named by John William Salter. The fossils referred to this species, recovered from Lesmahagow, Scotland, were soon realized to be distinct from other species of Pterygotus (such as the type species P. anglicus) and that same year geologist David Page erected a new genus to contain the species. The new genus, Slimonia , could be differentiated from other known species of Pterygotus most apparently by the lack of large cheliceral claws, otherwise a defining characteristic of Pterygotus.^[12]

In 1903, the genus Hughmilleria was created based on fossils discovered in the Pittsford Shale Member of the Vernon Formation. Its describer, the American geologist Clifton J. Sarle, considered the genus to represent an intermediate form between the more basal Eurypterus and the derived Pterygotus but did not assign Hughmilleria to any particular family.^[13]

The family Pterygotidae was erected in 1912 by John Mason Clarke and Rudolf Ruedemann to constitute a group for the genera Pterygotus, Slimonia, Hastimima and Hughmilleria.^[14]Pterygotus had also been designated as containing two subgenera; Pterygotus (Curviramus) and Pterygotus (Erettopterus), but Erettopterus would later be raised to its own genus.^[11] American paleontologist Erik N. Kjellesvig-Waering emended the Pterygotidae in 1951, referring the genera Hastimima, Hughmilleria and Slimonia, and the newly named Grossopterus , to their own family within the Eurypteracea, Hughmilleriidae, leaving Pterygotus as the sole pterygotid genus.^[11]

In 1955, Norwegian paleontologist and geologist Leif Størmer considered the pterygotid clade to represent a family within the eurypterid superfamily "Eurypteracea".^[5] In 1962, Russian paleontologist Nestor Ivanovich Novojilov raised the Eurypteracea and Pterygotidae to subordinal and superfamily status, Eurypteracea becoming the suborder Eurypterina and creating the superfamily Pterygotioidea, containing Hughmilleriidae and Pterygotidae.^[15]^[7] The same year, Novojilov also reclassified Slimonia into a pterygotioid family of its own as it was considered distinct enough from other hughmilleriids to warrant a separate family, the Slimonidae.^[10]

Classification

External phylogeny

Pterygotioids are classified within the infraorder Diploperculata, in the Eurypterina suborder of eurypterids.^[16] The infraorder Diploperculata contains the four most derived superfamilies of eurypterine eurypterids; Carcinosomatoidea, Adelophthalmoidea, Pterygotioidea and the waeringopteroids, united by the shared feature that the genital operculum (the structure that contains the genital appendage) is made up of two fused segments.^[17]

Pterygotioidea is the most derived superfamily of the suborder and contains over 50 species (the exact number obscured by dubious species and possible synonyms), which accounts for more than a fifth of the approximately 250 known eurypterid species. The closest sister group of the Pterygotioidea, Adelophthalmoidea, also contains a large amount of species, over 40, and is the second most diverse eurypterid superfamily.^[18]

The cladogram below is simplified from 2007 study by O. Erik Tetlie, showcasing the position of the pterygotioids within the suborder Eurypterina.^[18] Placement of Diploperculata follows Lamsdell et al. 2013.^[17]

Eurypterida

	Stylonurina

Pterygotioidea

	Pterygotidae

Internal phylogeny

Though the Pterygotidae are accepted to clearly represent the most derived group within the pterygotioid superfamily, there has been an ongoing debate on whether the hughmilleriids or the slimonids are the most closely related to the pterygotids, and thus also which of the two families is the most basal. This debate was resolved with the description of Ciurcopterus , a primitive pterygotid that clearly combines features of Slimonia (especially within the appendages) and of more derived pterygotid eurypterids, revealing that Slimonidae was the closest sister-group of the Pterygotidae.^[1]

The lack of ornamentation in the telson of Hughmilleria, combined with the fact that the genus shares certain characteristics with basal adelophthalmids (in particular the triangular anterior margin of the carapace), places it as the most basal genus in the superfamily.^[10]^[14]Hughmilleria also possessed far more gnathobasic (of the gnathobase, an appendage used in feeding) teeth than any other pterygotioid, possessing 18-20 whilst more derived pterygotioids (including related hughmilleriid Herefordopterus ) possessed only 12–13.^[10]

The cladogram presented below, derived from a 2007 study by researcher O. Erik Tetlie, showcases the interrelationships between the pterygotioid eurypterids.^[18] Whilst Slimonidae and Pterygotidae form monophyletic (and thus valid) groups,^[10] Hughmilleriidae has been recovered as paraphyletic in a number of phylogenetic analyses and does thus not form an actually valid scientific grouping.^[18]^[1]^[10] Nevertheless, the family is retained and routinely used by eurypterid researchers.^[16]

Pterygotioidea

Hughmilleria wangi

	Hughmilleria socialis

	Hughmilleria shawangunk

Herefordopterus banksii

Slimonia acuminata

Pterygotidae

Ciurcopterus ventricosus

Pterygotus anglicus

Jaekelopterus rhenaniae

	Acutiramus macrophthalmus

	Acutiramus bohemicus

Erettopterus bilobus

Erettopterus serricaudatus

	Erettopterus osiliensis

	Erettopterus waylandsmithi

Distribution

Eurypterids are most commonly recovered from fossil deposits in Scandinavia, Eastern Europe, Britain and North America. During the Silurian and Devonian periods, when pterygotioids were alive, these regions and continents were part of the continents Baltica (Scandinavia and Eastern Europe), Avalonia (Germany, Britain, parts of eastern North America) and Laurentia (most of eastern continental North America). It is around these continents, and the Rheno-Hercynian Terrane (western and central Europe), that pterygotioids are the most common.^[18]

Pterygotioid fossils have also been recovered from other parts of the world where fossils of other eurypterid groups are absent, including Australia, Morocco, Libya, Florida, Saudi Arabia, China, Paris, South America, Bohemia and Siberia, which indicates that the group had spread significantly during their 70 million year existence. Pterygotioids appear to have been relatively abundant throughout the Silurian and Devonian world, with unusually (in terms of eurypterids, most groups being absent entirely) large numbers recovered from the ancient continent of Gondwana (composed of Africa, India, South America, Australia and Antarctica).^[18]

The earliest known pterygotioids, belonging to the genus Hughmilleria, are from the Llandovery epoch of the Silurian and appear around the same time in Laurentia, Scotland and South China. With the group already being widespread at this seemingly early stage in their evolution, it is difficult to pinpoint their exact geographical point of origin. The closest relatives and sister clade of the pterygotioids, the superfamily Adelophthalmoidea, originated in Laurentia. Modern researchers assume that the case would be the same with the pterygotioids, which are thought to have originated within, or in close proximity to, Laurentia.^[18]

It remains unclear whether pterygotioids were capable of crossing oceans on a regular basis or if species recovered outside of Laurentia, Baltica and Avalonia represent isolated occurrences. Pterygotioids were, like the related adelophthalmoids, excellent swimmers which might help explain the intercontinental dispersal patterns and wide-ranging distribution seen in both superfamilies.^[18]

Related Research Articles

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 likely to have appeared first either during the Early Ordovician or Late Cambrian period. With approximately 250 species, the Eurypterida is the most diverse Paleozoic chelicerate order. Following their appearance during the Ordovician, eurypterids became major components of marine faunas during the Silurian, from which the majority of eurypterid species have been described. The Silurian genus Eurypterus accounts for more than 90% of all known eurypterid specimens. Though the group continued to diversify during the subsequent Devonian period, the eurypterids were heavily affected by the Late Devonian extinction event. They declined in numbers and diversity until becoming extinct during the Permian–Triassic extinction event 251.9 million years ago.

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 different species. Fossils have been recovered from four continents; Australia, Europe, North America and South America, which indicates that Pterygotus might have had a nearly cosmopolitan (worldwide) distribution. The type species, P. anglicus, was described by Swiss naturalist Louis Agassiz in 1839, who gave it the name Pterygotus, meaning "winged one". Agassiz mistakenly believed the remains were of a giant fish; he would only realize the mistake five years later in 1844.

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 related Salteropterus, the genus contains three valid species, S. acuminata from Lesmahagow, Scotland, S. boliviana from Cochabamba, Bolivia and S. dubia from the Pentland Hills of Scotland and one dubious species, S. stylops, from Herefordshire, England. The generic name is derived from and honors Robert Slimon, a fossil collector and surgeon from Lesmahagow.

Hughmilleria is a genus of eurypterid, an extinct group of aquatic arthropods. Fossils of Hughmilleria have been discovered in deposits of the Silurian age in China and the United States. Classified as part of the basal family Hughmilleriidae, the genus contains three species, H. shawangunk from the eastern United States, H. socialis from Pittsford, New York, and H. wangi from Hunan, China. The genus is named in honor of the Scottish geologist Hugh Miller.

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 North America and two from the Czech Republic. The generic name derives from Latin acuto and Latin ramus ("branch"), referring to the acute angle of the final tooth of the claws relative to the rest of the claw.

<i>Jaekelopterus</i> Extinct Devonian genus of the Eurypterida (sea scorpions)

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: the type species J. rhenaniae from brackish to fresh water strata in the Rhineland, and J. howelli from estuarine strata in Wyoming. The generic name combines the name of German paleontologist Otto Jaekel, who described the type species, and the Greek word πτερόν (pteron) meaning "wing".

<i>Nanahughmilleria</i> Extinct genus of arthropods

Nanahughmilleria is a genus of eurypterid, an extinct group of aquatic arthropods. Fossils of Nanahughmilleria have been discovered in deposits of Devonian and Silurian age in the United States, Norway, Russia, England and Scotland, and have been referred to several different species.

Pittsfordipterus is a genus of eurypterid, an extinct group of aquatic arthropods. Pittsfordipterus is classified as part of the family Adelophthalmidae, the only clade in the derived ("advanced") Adelophthalmoidea superfamily of eurypterids. Fossils of the single and type species, P. phelpsae, have been discovered in deposits of Silurian age in Pittsford, New York state. The genus is named after Pittsford, where the two only known specimens have been found.

Salteropterus is a genus of eurypterid, an extinct group of aquatic arthropods. Fossils of Salteropterus have been discovered in deposits of Late Silurian age in Britain. Classified as part of the family Slimonidae, the genus contains one known valid species, S. abbreviatus, which is known from fossils discovered in Herefordshire, England, and a dubious species, S. longilabium, with fossils discovered in Leintwardine, also in Herefordshire. The generic name honours John William Salter, who originally described S. abbreviatus as a species of Eurypterus in 1859.

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 to the Early Devonian, and have been referred to several different species. Fossils have been recovered from two continents; Europe and North America. The genus name is composed by the Ancient Greek words ἐρέττω (eréttō), which means "rower", and πτερόν (pterón), which means "wing", and therefore, "rower wing".

Parahughmilleria is a genus of eurypterid, an extinct group of aquatic arthropods. Fossils of Parahughmilleria have been discovered in deposits of the Devonian and Silurian age in the United States, Canada, Russia, Germany, Luxembourg and Great Britain, and have been referred to several different species. The first fossils of Parahughmilleria, discovered in the Shawangunk Mountains in 1907, were initially assigned to Eurypterus. It would not be until 54 years later when Parahughmilleria would be described.

Pterygotidae is a family of eurypterids, an extinct group of aquatic arthropods. They were members of the superfamily Pterygotioidea. Pterygotids were the largest known arthropods to have ever lived with some members of the family, such as Jaekelopterus and Acutiramus, exceeding 2 metres (6.6 ft) in length. Their fossilized remains have been recovered in deposits ranging in age from 428 to 372 million years old.

Adelophthalmidae is a family of eurypterids, an extinct group of aquatic arthropods. Adelophthalmidae is the only family classified as part of the superfamily Adelophthalmoidea, which in turn is classified within the infraorder Diploperculata in the suborder Eurypterina.

Eurypterina is one of two suborders of eurypterids, an extinct group of chelicerate arthropods commonly known as "sea scorpions". Eurypterine eurypterids are sometimes informally known as "swimming eurypterids". They are known from fossil deposits worldwide, though primarily in North America and Europe.

Hughmilleriidae is a family of eurypterids, an extinct group of aquatic arthropods. The hughmilleriids were the most basal members of the superfamily Pterygotioidea, in contrast with the more derived families Pterygotidae and Slimonidae. Despite their classification as pterygotioids, the hughmilleriids possessed several characteristics shared with other eurypterid groups, such as the lanceolate telson.

Slimonidae is a family of eurypterids, an extinct group of aquatic arthropods. Slimonids were members of the superfamily Pterygotioidea and the family most closely related to the derived pterygotid eurypterids, which are famous for their cheliceral claws and great size. Many characteristics of the Slimonidae, such as their flattened and expanded telsons, support a close relationship between the two groups.

Herefordopterus is a genus of eurypterid, an extinct group of aquatic arthropods. Herefordopterus is classified as part of the family Hughmilleriidae, a basal family in the highly derived Pterygotioidea superfamily of eurypterids. Fossils of the single and type species, H. banksii, have been discovered in deposits of Silurian age in Herefordshire and Shropshire, England. The genus is named after Herefordshire, where most of the Herefordopterus fossils have been found. The specific epithet honors Richard Banks, who found several well-preserved specimens, including the first Herefordopterus fossils.

<i>Necrogammarus</i> Extinct genus of arthropods

Necrogammarus salweyi is the binomial name applied to an arthropod fossil discovered in Herefordshire, England. The fossil represents a fragmentary section of the underside and an appendage of a pterygotid eurypterid, a group of large and predatory aquatic arthropods that lived from the late Silurian to the late Devonian. The Necrogammarus fossil is Late Silurian in age and its generic name means "dead lobster", deriving from Ancient Greek νεκρός and Latin gammarus ("lobster").

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. Classified as part of the family Pterygotidae, the genus contains two species, C. sarlei from Pittsford, New York and C. ventricosus from Kokomo, Indiana. The genus is named in honor of Samuel J. Ciurca, Jr., who has contributed significantly to eurypterid research by discovering a large amount of eurypterid specimens, including the four specimens used to describe Ciurcopterus itself.

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.

References

1 2 3 4 5 Tetlie, O. Erik; Briggs, Derek E. G. (2009-09-01). "The origin of pterygotid eurypterids (Chelicerata: Eurypterida)". Palaeontology. 52 (5): 1141–1148. Bibcode:2009Palgy..52.1141T. doi:10.1111/j.1475-4983.2009.00907.x. ISSN 1475-4983. S2CID 84268058.
↑ Olive, Sébastien; Pradel, Alan; Martinez-Pérez, Carlos; Janvier, Philippe; Lamsdell, James C.; Gueriau, Pierre; Rabet, Nicolas; Duranleau-Gagnon, Philippe; Cardenas-Rozo, Andres L.; Zapata Ramirez, Paula A.; Botella, Héctor (2019). "New insights into Late Devonian vertebrates and associated fauna from the Cuche Formation (Floresta Massif, Colombia)". Journal of Vertebrate Paleontology . 39 (3): e1620247. Bibcode:2019JVPal..39E0247O. doi:10.1080/02724634.2019.1620247. hdl: 10784/26939 . S2CID 198237241.
↑ Lamsdell, James C.; Braddy, Simon J. (2009). "Cope's rule and Romer's theory: patterns of diversity and gigantism in eurypterids and Palaeozoic vertebrates". Biology Letters . 6 (2): 265–269. doi:10.1098/rsbl.2009.0700. ISSN 1744-9561. PMC 2865068 . PMID 19828493. Supplemental material.
↑ Braddy, Simon J.; Poschmann, Markus; Tetlie, O. Erik (2007). "Giant claw reveals the largest ever arthropod". Biology Letters . 4 (1): 106–109. doi:10.1098/rsbl.2007.0491. PMC 2412931 . PMID 18029297.
1 2 3 Størmer, Leif (1955). "Merostomata". Treatise on Invertebrate Paleontology, Part P Arthropoda 2, Chelicerata. p. 23.
↑ Tollerton, V. P. (1989). "Morphology, taxonomy, and classification of the order Eurypterida Burmeister, 1843". Journal of Paleontology. 63 (5): 642–657. Bibcode:1989JPal...63..642T. doi:10.1017/S0022336000041275. ISSN 0022-3360. S2CID 46953627.
1 2 Plotnick, Roy E.; Baumiller, Tomasz K. (1988-01-01). "The pterygotid telson as a biological rudder". Lethaia. 21 (1): 13–27. Bibcode:1988Letha..21...13P. doi:10.1111/j.1502-3931.1988.tb01746.x. ISSN 1502-3931.
↑ Clarke, J. K., Ruedemann R. (1912) "The Eurypterida of New York"
↑ Murchison, Roderick Impey (1839). The Silurian System, Founded on Geological Researches in the Counties of Salop, Hereford, Radnor, Montgomery, Caermarthen, Brecon, Pembroke, Monmouth, Gloucester, Worcester, and Stafford: With Descriptions of the Coalfields and Overlying Formations. Albemarle Street. p. 606. Note that this work incorrectly translates Pterygotus as "winged fish", but there is no "fish" element in the name.
1 2 3 4 5 6 Tetlie, O. Erik (2006). "Eurypterida (Chelicerata) from the Welsh Borderlands, England". Geological Magazine. 143 (5): 723–735. Bibcode:2006GeoM..143..723T. doi:10.1017/S0016756806002536. ISSN 1469-5081. S2CID 83835591.
1 2 3 Kjellesvig-Waering, Erik N. (1964). "A Synopsis of the Family Pterygotidae Clarke and Ruedemann, 1912 (Eurypterida)". Journal of Paleontology. 38 (2): 331–361. JSTOR 1301554.
↑ Nicholson, Henry Alleyne (1868-01-01). "III. On the Occurrence of Fossils in the Old Red Sandstone of Westmoreland". Transactions of the Edinburgh Geological Society. 1 (1): 15–18. doi:10.1144/transed.1.1.15. ISSN 0371-6260. S2CID 131539776.
↑ Sarle, Clifton J. (1902). "A new eurypterid fauna from the base of the Salina of western New York". New York State Museum Bulletin. 69: 1080–1108.
1 2 Ciurca, Samuel J.; Tetlie, O. Erik (2007). "Pterygotids (Chelicerata; Eurypterida) from the Silurian Vernon Formation of New York". Journal of Paleontology. 81 (4): 725–736. doi:10.1666/pleo0022-3360(2007)081[0725:PEFTSV]2.0.CO;2. ISSN 0022-3360. S2CID 140668235.
↑ Novojilov, N. 1962: Order Eurypterida. In Orlov, J. A. (ed.): Osnovy Paleontologii - volume 7, 404-423. Akademii Nauk SSSR, Moscow.
1 2 Dunlop, J. A.; Penney, D.; Jekel, D. (2018). "A summary list of fossil spiders and their relatives" (PDF). World Spider Catalog. Natural History Museum Bern.
1 2 Lamsdell, James; Hoşgör, Izzet; Selden, Paul (2013-01-31). "A new Ordovician eurypterid (Arthropoda: Chelicerata) from southeast Turkey: Evidence for a cryptic Ordovician record of Eurypterida". Gondwana Research. 23 (1): 354–366. Bibcode:2013GondR..23..354L. doi:10.1016/j.gr.2012.04.006.
1 2 3 4 5 6 7 8 Tetlie, O. Erik (2007). "Distribution and dispersal history of Eurypterida (Chelicerata)" (PDF). Palaeogeography, Palaeoclimatology, Palaeoecology . 252 (3–4): 557–574. Bibcode:2007PPP...252..557T. doi:10.1016/j.palaeo.2007.05.011. Archived from the original (PDF) on 2011-07-18.

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[:0222-1] 1 2 3 4 5 Tetlie, O. Erik; Briggs, Derek E. G. (2009-09-01). "The origin of pterygotid eurypterids (Chelicerata: Eurypterida)". Palaeontology. 52 (5): 1141–1148. Bibcode:2009Palgy..52.1141T. doi:10.1111/j.1475-4983.2009.00907.x. ISSN 1475-4983. S2CID 84268058.

[fras-2] Olive, Sébastien; Pradel, Alan; Martinez-Pérez, Carlos; Janvier, Philippe; Lamsdell, James C.; Gueriau, Pierre; Rabet, Nicolas; Duranleau-Gagnon, Philippe; Cardenas-Rozo, Andres L.; Zapata Ramirez, Paula A.; Botella, Héctor (2019). "New insights into Late Devonian vertebrates and associated fauna from the Cuche Formation (Floresta Massif, Colombia)". Journal of Vertebrate Paleontology . 39 (3): e1620247. Bibcode:2019JVPal..39E0247O. doi:10.1080/02724634.2019.1620247. hdl: 10784/26939 . S2CID 198237241.

[:7-3] Lamsdell, James C.; Braddy, Simon J. (2009). "Cope's rule and Romer's theory: patterns of diversity and gigantism in eurypterids and Palaeozoic vertebrates". Biology Letters . 6 (2): 265–269. doi:10.1098/rsbl.2009.0700. ISSN 1744-9561. PMC 2865068 . PMID 19828493. Supplemental material.

[Braddy-4] Braddy, Simon J.; Poschmann, Markus; Tetlie, O. Erik (2007). "Giant claw reveals the largest ever arthropod". Biology Letters . 4 (1): 106–109. doi:10.1098/rsbl.2007.0491. PMC 2412931 . PMID 18029297.

[:4-5] 1 2 3 Størmer, Leif (1955). "Merostomata". Treatise on Invertebrate Paleontology, Part P Arthropoda 2, Chelicerata. p. 23.

[:02-6] Tollerton, V. P. (1989). "Morphology, taxonomy, and classification of the order Eurypterida Burmeister, 1843". Journal of Paleontology. 63 (5): 642–657. Bibcode:1989JPal...63..642T. doi:10.1017/S0022336000041275. ISSN 0022-3360. S2CID 46953627.

[:14-7] 1 2 Plotnick, Roy E.; Baumiller, Tomasz K. (1988-01-01). "The pterygotid telson as a biological rudder". Lethaia. 21 (1): 13–27. Bibcode:1988Letha..21...13P. doi:10.1111/j.1502-3931.1988.tb01746.x. ISSN 1502-3931.

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[:12-9] Murchison, Roderick Impey (1839). The Silurian System, Founded on Geological Researches in the Counties of Salop, Hereford, Radnor, Montgomery, Caermarthen, Brecon, Pembroke, Monmouth, Gloucester, Worcester, and Stafford: With Descriptions of the Coalfields and Overlying Formations. Albemarle Street. p. 606. Note that this work incorrectly translates Pterygotus as "winged fish", but there is no "fish" element in the name.

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[12] Nicholson, Henry Alleyne (1868-01-01). "III. On the Occurrence of Fossils in the Old Red Sandstone of Westmoreland". Transactions of the Edinburgh Geological Society. 1 (1): 15–18. doi:10.1144/transed.1.1.15. ISSN 0371-6260. S2CID 131539776.

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[15] Novojilov, N. 1962: Order Eurypterida. In Orlov, J. A. (ed.): Osnovy Paleontologii - volume 7, 404-423. Akademii Nauk SSSR, Moscow.

[:022-16] 1 2 Dunlop, J. A.; Penney, D.; Jekel, D. (2018). "A summary list of fossil spiders and their relatives" (PDF). World Spider Catalog. Natural History Museum Bern.

[:0-17] 1 2 Lamsdell, James; Hoşgör, Izzet; Selden, Paul (2013-01-31). "A new Ordovician eurypterid (Arthropoda: Chelicerata) from southeast Turkey: Evidence for a cryptic Ordovician record of Eurypterida". Gondwana Research. 23 (1): 354–366. Bibcode:2013GondR..23..354L. doi:10.1016/j.gr.2012.04.006.

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