Hughmilleriidae

Hughmilleriidae; Temporal range: Silurian, 442–418.7 Ma PreꞒ Ꞓ O S D C P T J K Pg N
	Fossils of Hughmilleria socialis
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Chelicerata
Order:	† Eurypterida
Infraorder:	† Diploperculata
Superfamily:	† Pterygotioidea
Family:	† Hughmilleriidae ; Kjellesvig-Waering, 1951
Type species
	† Hughmilleria socialis ; Sarle, 1903
Genera
	† Herefordopterus ; † Hughmilleria ;

Last updated September 25, 2023

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 members of the superfamily Pterygotioidea, in contrast with the more derived (more "advanced") families Pterygotidae and Slimonidae. Despite their classification as pterygotioids, the hughmilleriids possessed several characteristics shared with other eurypterid groups, such as the lanceolate telson (the most posterior segment of the body).

Hughmilleriids are defined as pterygotioid eurypterids with swimming legs similar to those of the type genus, Hughmilleria (that is, 7th and 8th leg segments narrow and 9th segment very small), and whose second to fifth pair of appendages were spiniferous. Some further diagnostic characters unite the group, such as the slightly enlarged chelicerae (frontal appendages) and the streamlined shape of their bodies. The family contains only two genera, Hughmilleria and Herefordopterus , though other genera have been referred to the family in the past, such as genera now considered part of families such as the Mycteroptidae and the Waeringopteridae.

The hughmilleriids were the most basal group of pterygotioid eurypterids, lacking the derived features that would come to evolve in the Slimonidae and Pterygotidae, such as flattened and expanded telsons (the posteriormost segment of the body, this feature is shared by both derived families) and enlarged cheliceral claws (exclusive to the pterygotids). In spite of the great similarity of both genera, Herefordopterus had derived characteristics that suggest a close relationship with Slimonidae and Pterygotidae, such as the marginal ornamentation of the telson. On the other hand, Hughmilleria had certain resemblance to the basal adelophthalmid Eysyslopterus , sharing a triangular anterior carapace margin, possibly a plesiomorphic (of a common ancestor) trait.

Description

Hughmilleriid eurypterids ranged in size from 6 to 20 centimetres (2 to 8 inches),^[1] representing a group of relatively small eurypterids. Hughmilleriids would be dwarfed by some of their more derived (more "advanced") relatives within their superfamily, especially the pterygotids which would surpass lengths of 2 metres and become the largest known arthropods to ever live.^[1]

Like all other chelicerates, and other arthropods in general, the hughmilleriid eurypterids possessed segmented bodies and jointed appendages (limbs) covered in a cuticle composed of proteins and chitin. 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 hughmilleriids as being spiniferous (possessing spines), a feature that distinguishes the group from the pterygotids and the slimonids, both groups possessing non-spiniferous appendages.^[2] The telson (the posteriormost segment of the body), which was lanceolate and styliform, is a feature shared with other eurypterid groups, such as the closely related Adelophthalmoidea.^[3] Although these telsons were not flattened and expanded as in both derived families, Herefordopterus had a keel and marginal ornamentation, characteristics also noted within Pterygotidae.^[4] The lanceolate shape of their telsons suggests they did not use it as a rudder to swim.^[5]

The family is characterized by the presence of spines in the second to fifth pair of appendages, swimming legs with the 7th and 8th leg segments narrow, both twice as long as wide, and the 9th segment small,^[2] small and streamlined bodies, slightly enlarged chelicerae (frontal appendages) and a marginal rim in the carapace much broader anteriorly than posteriorly.^[6]^[4]

History of research

The genus Hughmilleria was erected by Clifton J. Sarle in 1903 to contain the species H. socialis, which was recovered for the first time in the Pittsford Shale Member of the Vernon Formation.^[7]^[8] The generic name derives from Hugh Miller, a Scottish geologist and writer that found fossils of several Silurian eurypterids, such as Hughmilleria itself.^[9] Sarle considered Hughmilleria as an intermediate form between Eurypterus and Pterygotus. However, he did not assigned Hughmilleria to any family.^[7]

Hughmilleria was first considered as a genus in the Pterygotidae, being one of the initial members of that family alongside Pterygotus , Slimonia and Hastimima upon its creation by John Mason Clarke and Rudolf Ruedemann in 1912. The family Hughmilleriidae was created by Erik N. Kjellesvig-Waering in 1951, who considered the genera Hastimima, Slimonia and Hughmilleria and the new genus Grossopterus sufficiently distinct from Pterygotus to be in a family of their own.^[10]Slimonia was considered too distinct from Hughmilleria in 1962, placed by Nestor Ivanovich Novojilov in its own family, the Slimonidae.^[4] The other hughmilleriids would also be reclassified, Hastimima representing a mycteroptidae and Grossopterus a waeringopterid.^[11]

This left Hughmilleria as the only genus in the family, rendering it monotypic (including only one subordinate taxon). Hughmilleriidae remained monotypic until a species of Hughmilleria, H. banksii, was raised to the level of a separate genus, Herefordopterus , by O. Erik Tetlie in 2006. With two genera of hughmilleriids known, several diagnostic traits of the family could properly be established, such as the presence of spiniferous appendages.^[12]

Classification

The Hughmilleriidae are classified as part of the Pterygotioidea superfamily, within the Diploperculata infraorder and Eurypterina suborder.^[11] The Hughmilleriidae has sometimes been interpreted as the sister-taxon of the Pterygotidae. Sarle interpreted Hughmilleria in 1903 as an intermediate form between Eurypterus and Pterygotus, being closer to the latter. For this to happen, the loss of spines in Slimonia and the pterygotids would be convergent.^[12] The discovery of Ciurcopterus , the most primitive known pterygotid, and studies revealing that Ciurcopterus combines features of Slimonia (the appendages are particularly similar) and of more derived pterygotids, revealed that the Slimonidae was more closely related to the Pterygotidae than the Hughmilleriidae was, establishing Hughmilleriidae as the most basal group of pterygotioid eurypterids.^[12] The family has been recovered as paraphyletic in a number of phylogenetic analyses and does thus not form an actually valid scientific grouping.^[13]^[12]^[4] Nevertheless, the family is retained and routinely used by eurypterid researchers.^[11]

Within the family, both genera shared several characteristics such as the carapace being much broader anteriorly than posteriorly, appendages II-V being spiniferous (possessing spines),^[4] swimming legs similar to those of Hughmilleria itself, the slight enlargement of their chelicerae and their small and streamlined bodies.^[2]^[6] However, the marginal ornamentation of the telson and the possession of 12-13 gnathobasic (of the gnathobase, a lower appendage used in feeding) teeth in the appendage VI suggests that Herefordopterus was a derived hughmilleriid. In turn, Hughmilleria lacked the marginal ornamentation of the telson and its appendage VI had 18-20 gnathobasic teeth, so it is considered the most basal genus of Pterygotioidea.^[4] The triangular anterior carapace margin present in Hughmilleria is shared by the adelophthalmid eurypterid Eysyslopterus , indicating that it might be a plesiomorphic trait (a trait present in a common ancestor).^[14]

The cladogram presented below, derived from a 2007 study by researcher O. Erik Tetlie, showcases the interrelationships between the pterygotioid eurypterids.^[13]

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

Paleoecology

The fossils of the hughmilleriids have been found in Silurian deposits ranging from the Llandovery to Ludlow epochs in the United States, China and England.^[11] While Hughmilleria lived in brackish and fresh water communities,^[15]Herefordopterus was present in a benthic (at the lowest level of water) environment near an intertidal sandy shore and intertidal sandy mudflat environments.^[16]

The Silurian deposits of the Pittsford Shale Member in which fossils of Hughmilleria socialis have been found shelter various faunas of eurypterids, including Mixopterus multispinosus , Erettoperus osiliensis , Eurypterus pittsfordensis and Carcinosoma spiniferus , among others.^[17] In the other hand, the Late Silurian of Herefordshire, where most of the fossils of Herefordopterus have been discovered, was home to a wide array of different eurypterids, like Erettopterus gigas , Eurypterus cephalaspis , Nanahughmilleria pygmaea , Marsupipterus sculpturatus , Salteropterus abbreviatus and potentially Slimonia (depending on the identity of S. stylops).^[18]

Related Research Articles

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 well-known eurypterid. Eurypterus fossil specimens probably represent more than 95% of all known eurypterid specimens.

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.

Carcinosoma is a genus of eurypterid, an extinct group of aquatic arthropods. Fossils of Carcinosoma are restricted to deposits of late Silurian age. Classified as part of the family Carcinosomatidae, which the genus lends its name to, Carcinosoma contains seven species from North America and Great Britain.

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. Seven 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>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.

Unionopterus is a genus of eurypterid, an extinct group of aquatic arthropods commonly known as "sea scorpions". Fossils have been registered from the Early Carboniferous period. The genus contains only one species, U. anastasiae, recovered from deposits of Tournaisian to Viséan stages in Kazakhstan. Known from one single specimen which was described in a publication of Russian language with poor illustrations, Unionopterus' affinities are extremely poorly known.

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.

Carcinosomatidae is a family of eurypterids, an extinct group of aquatic arthropods. They were members of the superfamily Carcinosomatoidea, also named after Carcinosoma. Fossils of carcinosomatids have been found in North America, Europe and Asia, the family possibly having achieved a worldwide distribution, and range in age from the Late Ordovician to the Early Devonian. They were among the most marine eurypterids, known almost entirely from marine environments.

Pterygotioidea 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.

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 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.
1 2 3 Tollerton, V. P. (1989). "Morphology, taxonomy, and classification of the order Eurypterida Burmeister, 1843". Journal of Paleontology. 63 (5): 642–657. doi:10.1017/S0022336000041275. ISSN 0022-3360. S2CID 46953627.
↑ Erik Tetlie; Paul A Selden; Dong Ren (2007). "A new Silurian eurypterid (Arthropoda: Chelicerata) from China". Palaeontology. 50 (3): 619–625. doi:10.1111/j.1475-4983.2007.00651.x. hdl: 1808/8354 . S2CID 56066870.
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.
↑ Plotnick, Roy E.; Baumiller, Tomasz K. (1988-01-01). "The pterygotid telson as a biological rudder". Lethaia. 21 (1): 13–27. doi:10.1111/j.1502-3931.1988.tb01746.x. ISSN 1502-3931.
1 2 Paul A. Selden. "Autecology of Silurian eurypterids". Special Papers in Palaeontology. 32.
1 2 Sarle, Clifton J. (1902). "A new eurypterid fauna from the base of the Salina of western New York". 69. New York State Museum Bulletin: 1080–1108.{{cite journal}}: Cite journal requires |journal= (help)
↑ Clarke, J. K., Ruedemann R. (1912) "The Eurypterida of New York"
↑ Charles Blinderman (1 January 1990). Biolexicon: A Guide to the Language of Biology. Charles C Thomas Publisher. ISBN 978-0-398-08227-7.
↑ 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.
1 2 3 4 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 18.5 http://www.wsc.nmbe.ch/resources/fossils/Fossils18.5.pdf (PDF).
1 2 3 4 Tetlie, O. Erik; Briggs, Derek E. G. (2009-09-01). "The origin of pterygotid eurypterids (Chelicerata: Eurypterida)". Palaeontology. 52 (5): 1141–1148. doi: 10.1111/j.1475-4983.2009.00907.x . ISSN 1475-4983.
1 2 Tetlie, O. Erik (2007). "Distribution and dispersal history of Eurypterida (Chelicerata)" (PDF). Palaeogeography, Palaeoclimatology, Palaeoecology . 252 (3–4): 557–574. doi:10.1016/j.palaeo.2007.05.011. Archived from the original (PDF) on 2011-07-18.
↑ 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.
↑ Michael J. Benton & David A. T. Harper (2009). "Ecdysozoa: arthropods". Introduction to paleobiology and the fossil record. Wiley-Blackwell. pp. 361–388. ISBN 978-1-4051-4157-4.
↑ Burkert, C. (2018). "Environment preference of eurypterids–indications for freshwater adaptation?".{{cite journal}}: Cite journal requires |journal= (help)
↑ "Eurypterid-Associated Biota of the Pittsford Shale, Pittsford, New York: Ludlow, New York". The Paleobiology Database.
↑ "Fossilworks - Eurypterid-Associated Biota of the Temeside Shale, Ludlow and Perton, England (Silurian of the United Kingdom)". fossilworks.org.

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[:32-1] 1 2 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.

[:0-2] 1 2 3 Tollerton, V. P. (1989). "Morphology, taxonomy, and classification of the order Eurypterida Burmeister, 1843". Journal of Paleontology. 63 (5): 642–657. doi:10.1017/S0022336000041275. ISSN 0022-3360. S2CID 46953627.

[newsp-3] Erik Tetlie; Paul A Selden; Dong Ren (2007). "A new Silurian eurypterid (Arthropoda: Chelicerata) from China". Palaeontology. 50 (3): 619–625. doi:10.1111/j.1475-4983.2007.00651.x. hdl: 1808/8354 . S2CID 56066870.

[:13-4] 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.

[telson-5] Plotnick, Roy E.; Baumiller, Tomasz K. (1988-01-01). "The pterygotid telson as a biological rudder". Lethaia. 21 (1): 13–27. doi:10.1111/j.1502-3931.1988.tb01746.x. ISSN 1502-3931.

[selden-6] 1 2 Paul A. Selden. "Autecology of Silurian eurypterids". Special Papers in Palaeontology. 32.

[l-7] 1 2 Sarle, Clifton J. (1902). "A new eurypterid fauna from the base of the Salina of western New York". 69. New York State Museum Bulletin: 1080–1108.{{cite journal}}: Cite journal requires |journal= (help)

[fi-8] Clarke, J. K., Ruedemann R. (1912) "The Eurypterida of New York"

[miller-9] Charles Blinderman (1 January 1990). Biolexicon: A Guide to the Language of Biology. Charles C Thomas Publisher. ISBN 978-0-398-08227-7.

[:22-10] 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.

[:1-11] 1 2 3 4 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 18.5 http://www.wsc.nmbe.ch/resources/fossils/Fossils18.5.pdf (PDF).

[:022-12] 1 2 3 4 Tetlie, O. Erik; Briggs, Derek E. G. (2009-09-01). "The origin of pterygotid eurypterids (Chelicerata: Eurypterida)". Palaeontology. 52 (5): 1141–1148. doi: 10.1111/j.1475-4983.2009.00907.x . ISSN 1475-4983.

[tetlie2007-13] 1 2 Tetlie, O. Erik (2007). "Distribution and dispersal history of Eurypterida (Chelicerata)" (PDF). Palaeogeography, Palaeoclimatology, Palaeoecology . 252 (3–4): 557–574. doi:10.1016/j.palaeo.2007.05.011. Archived from the original (PDF) on 2011-07-18.

[:5-14] 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.

[15] Michael J. Benton & David A. T. Harper (2009). "Ecdysozoa: arthropods". Introduction to paleobiology and the fossil record. Wiley-Blackwell. pp. 361–388. ISBN 978-1-4051-4157-4.

[16] Burkert, C. (2018). "Environment preference of eurypterids–indications for freshwater adaptation?".{{cite journal}}: Cite journal requires |journal= (help)

[17] "Eurypterid-Associated Biota of the Pittsford Shale, Pittsford, New York: Ludlow, New York". The Paleobiology Database.

[y-18] "Fossilworks - Eurypterid-Associated Biota of the Temeside Shale, Ludlow and Perton, England (Silurian of the United Kingdom)". fossilworks.org.

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