Slimonia

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Slimonia
Temporal range: Silurian, 436–420  Ma
Slimonia acuminata 1.jpg
Fossil of S. acuminata housed at the Senckenberg Museum of Frankfurt
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Chelicerata
Order:† Eurypterida
Superfamily:† Pterygotioidea
Family:† Slimonidae
Genus:† Slimonia
Page, 1856
Type species
†Slimonia acuminata
Salter, 1856
Species
  • †S. acuminataSalter, 1856
  • †S. bolivianaKjellesvig-Waering, 1973
  • †S. dubiaLaurie, 1899
  • †?S. stylopsSalter, 1859

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.

Contents

Out of the four described species of Slimonia, three measured below or up to 20 centimetres (7.9 in) in length. Only S. acuminata was larger, with the largest specimens measuring 100 centimetres (39 in) in length. Though this is large for a predatory arthropod, Slimonia would be exceeded in length by later and more derived (more "advanced") members of the closely related pterygotid family of eurypterids, which would become the largest known arthropods to ever live.

Description

Life restoration of S. acuminata. The short chelicerae are hidden beneath the head. Slimonia acuminata reconstruction.jpg
Life restoration of S. acuminata. The short chelicerae are hidden beneath the head.

Slimonia is in many ways similar to the more derived (more "advanced") eurypterids of its superfamily, the Pterygotioidea. In particular, the expanded and flattened telson (the most posterior segment of the body) of Slimonia is similar to that of the pterygotid eurypterids and is a feature that Slimonia and the pterygotids only share with some derived hibbertopterid eurypterids (where the feature convergently evolved). [1] The pterygotid telson was in general slightly larger than that of Slimonia and was more slender. The telson spike of Slimonia was much longer than any seen in the Pterygotidae (constituting just over half of the total telson length) however, serrated and ending in a fine point. [2] The largest species of Slimonia, S. acuminata, reached a maximum length of 100 cm (39 in) whilst the smallest, S. dubia, grew to 12 cm (5 in) in length. [3] Though 100 cm is large for a predatory arthropod, Slimonia would be exceeded in length by later and more derived (more "advanced") members of the closely related pterygotid family of eurypterids, which would become the largest known arthropods to ever live. [4]

Slimonia can be distinguished from other members of its family, the Slimonidae, by a variety of characteristics. The prosoma (head) is quadrate (square-shaped) in shape and had small compound eyes on the frontal corners. The bodies were large and cordate (heart-shaped), with a narrow postabdomen and a telson with a strongly expanded anterior half. The chelicerae (frontal appendages) were small in comparison to those of the pterygotids and the walking legs had denticles, but no spines. Genital appendages were long and narrow in both males and females. [5]

History of research

Fossil of S. acuminata A monograph of the British fossil Crustacea (Pl. XVII) (7394026154).jpg
Fossil of S. acuminata

The type species of Slimonia, S. acuminata, was first described as a species of Pterygotus, "Pterygotus acuminata" (acuminata being Latin for "sharp" or "tapering"), by John William Salter in 1856, based on fossils recovered from deposits of Llandovery-Wenlock (Early to Middle Silurian) age in Lesmahagow, Scotland. That same year David Page erected a new genus to contain the species, as several distinctive characteristics made the species considerably different from other known species of Pterygotus, among them the shape of the carapace and S. acuminata lacking the large cheliceral claws known from Pterygotus. [6] The generic name is derived from and honors Robert Slimon, a fossil collector and surgeon from Lesmahagow. Slimon was the first to discover eurypterid fossils in Lesmahagow, bringing them to the attention of Roderick Murchison in 1851. [7] S. acuminata remains the largest known species, with the largest specimens measuring up to 100 cm (39 in) in length. [3]

In 1899, an additional species, S. dubia, would be referred to the genus. This species was recovered from slightly earlier deposits (Llandovery age) in the Pentland Hills of Scotland and could be distinguished from S. acuminata by the more elongated telson (also not as broad in the parts furthest back), thinner telson spike and a slightly different, tapering, body shape that tapers evenly the whole way instead of suddenly narrowing near the seventh segment as in S. acuminata. [8] [9] The type specimen of S. dubia is a badly preserved carapace, with fragments of various degrees of completion of the first eleven segments found associated. Despite its fragmentary nature, the quadrangular (square) shape of the carapace and the eyes placed at its corners allowed zoologist and paleontologist Malcolm Laurie to place it within Slimonia when describing it in 1899. [8] The size of the carapace suggests that the species would have grown to 12 cm (5 in) in length. [3]

Another species, S. stylops, was first considered a species of Pterygotus when described by John William Salter in 1859, and the highly fragmentary nature of the known fossils make a precise identification difficult and problematic. Only one specimen, the anterior part of a carapace with the compound eyes placed on the margin, is known and though it does resemble Slimonia, it could also potentially be referred to Hughmilleria or even represent the carapace of Salteropterus abbreviatus (a closely related slimonid eurypterid known only from the telson and metastoma, a large plate part of the abdomen). [10] The fossils were recovered from deposits of Pridoli (Late Silurian) age in Herefordshire, England and suggest that the species grew to 12 cm (5 in) in length. [3] Due to its problematic nature, S. stylops is seen as a nomen dubium by modern researchers. [11]

In 1973, another species of Slimonia was named by Kjellesvig-Waering based on one single fossil recovered by Eduardo Rodriguez from the Kirusillas Formation, of Ludlow-Pridoli (Late Silurian) age, in Cochabamba, Bolivia. Named S. boliviana, the holotype (BLV15, deposited at the National Museum of Natural History of France) comprises a well-preserved telson typical of the genus, being laterally inflated and with a dagger-like terminal point. It was anteriorly covered with small scales semilunar to mucronitic ("spined") grouped into a single row of large marginal scales that form a linear serrated edge. A slight dorsal keel is present along the telson. There was a triangular area at the base of the telson which could have been a point of union with the muscles. S. boliviana differed from S. acuminata in having the keel much less developed, narrower and not reaching the terminal spike. The latter was wider, not as pointed and with less developed serrations. The telson itself was wider and shorter than in the type species. This species was the third Silurian eurypterid in the Southern Hemisphere to be described, the other two coming from Australia. [12] The fossil suggest a total body length of 20 centimetres (7.9 in). [3]

Classification

Ventral and dorsal views of S. acuminata. Note the ventral view is missing the short chelicerae that were actually present. A monograph of the British fossil Crustacea (Pl. XX) (7394030590).jpg
Ventral and dorsal views of S. acuminata. Note the ventral view is missing the short chelicerae that were actually present.
Life restoration of S. acuminata. Note the short chelicerae are hidden beneath the head. Slimonia NT small.jpg
Life restoration of S. acuminata. Note the short chelicerae are hidden beneath the head.

Slimonia is classified as part of the eurypterid family Slimonidae, within the superfamily Pterygotioidea. [11] Historically Slimonia was first considered a member of the Pterygotidae, until it was reclassified alongside Hughmilleria and other genera to the family Hughmilleriidae in 1951 by Erik N. Kjellesvig-Waering. [13] Nestor Ivanovich Novojilov classified Slimonia as part of a family of its own in 1968. [11]

Slimonia is one of the most closely related genera to the pterygotid family and the Slimonidae is often interpreted as a sister-taxon to the Pterygotidae. The other Pterygotioid family, the Hughmilleriidae, has also been interpreted as the most closely related sister-taxon to the pterygotids. 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 is more closely related to the Pterygotidae than the Hughmilleriidae is. [14]

The cladogram below is simplified from a study by O. Erik Tetlie (2007), [15] and showcases the position of Slimonia relative to the rest of the Eurypterina suborder of eurypterids, with the Stylonurina suborder as an outgroup.

Eurypterida

Paleobiology

Drawing of the holotype of S. boliviana, a telson. Slimonia boliviana telson.png
Drawing of the holotype of S. boliviana, a telson.

In 2017, W. Scott Persons IV and John Acorn reported finding an S. acuminata specimen, MB.A 863, in the Patrick Burn Formation of Scotland, dated to the Telychian, around 430 million years ago. The specimen was a complete and articulated series of telsonal, postabdominal and preabdominal segments, and it showed a very strong lateral curvature in the postabdomen. Persons and Acorn admitted that it might have experienced some disarticulation postmortem or could represent a partial molt (exuviae), but concluded that since there was no apparent disarticulation in the metasoma, it was likely that the articulation seen in the postabdominal segments (which is also seen in some other eurypterid fossils, such as of Eurypterus and Alkenopterus ) would have been possible in life. [2]

Biomechanical studies on the telsons and postabdominal segments of eurypterids closely related to Slimonia, particularly those of the family Pterygotidae, had revealed that the body was very stiff, and that the flattened telson would likely have served as a rudder that would have allowed the animals to be agile and capable of quick turns when chasing after prey, contradicting previous hypotheses that the telson would have served a propulsive function. [1] Whilst the postabdomen of Slimonia was likely similarly stiff and inflexible dorsally (up and down), Persons and Acorn claimed that their specimen suggested that it was highly flexible laterally (side to side). As such, they theorised that the tail may have been used as a weapon. The telson spine, serrated along the sides and exceeding the flattened telson in length, ends in a sharp tip, and they proposed that it could have been capable of piercing prey. [2] [16]

However, the Persons and Acorn theory was challenged in 2018 by James Lamsdell, David Marshall, and Derek Briggs. Even though the Persons and Acorn study claimed that the fossil didn't show any signs of disarticulation, Lamsdell, Marshall, and Briggs showed this is likely not true. They argued that both tergite 8 and 10 clearly overlapped the other tergites in an unnatural way. Furthermore, they noted that the specimen was definitely a molt rather than a carcass, and argued that this meant that the pose the fossil was in did not represent a possible life position. They further argued that since the telson of Slimonia also possessed a keel, this would have created significant drag on it while Slimonia was trying to laterally sweep the telson to stab its prey. Lastly, they argued that the serrations on the telson would most likely be attachment points for setae that would have aided the animal in sensing the water flow to make steering much easier. [17]

Reconstruction of Slimonia acuminata featuring short chelicerae below the head. Slimonia.jpg
Reconstruction of Slimonia acuminata featuring short chelicerae below the head.

Visual acuity, the clarity of vision, can be determined in arthropods by determining number of lenses in their compound eyes and the interommatidial angle (shortened as IOA and referring to the angle between the optical axes of the adjacent lenses). The IOA is especially important as it can be used to distinguish different ecological roles in arthropods, being low in modern active arthropod predators. [18] Slimonia was very similar to the basal pterygotid Erettopterus in terms of visual acuity, with the number of lenses being comparable to those of Pterygotus and Jaekelopterus and possessing an IOA between 2 and 3 (which is higher than the IOA of Pterygotus and Jaekelopterus, suggesting that the visual acuity of Slimonia was good, but not as good as in the derived pterygotids). [18]

Paleoecology

The size of the largest (S. acuminata) and smallest (S. dubia) species of Slimonia compared to a human. Slimonia Size.png
The size of the largest (S. acuminata) and smallest (S. dubia) species of Slimonia compared to a human.

Fossils of Slimonia have been recovered in deposits home to diverse eurypterid faunas. Telychian deposits in the Pentland Hills, where remains of S. dubia have been found, preserve fossils of a large amount of other eurypterids, including Drepanopterus pentlandicus , Laurieipterus elegans , Parastylonurus ornatus , Hardieopterus macrophthalmus , Carcinosoma scoticus , Stoermeropterus conicus and Pentlandopterus minor . Also preserved are fossils of orthocerids, such as Geisonoceras maclareni . [8] Similar levels of eurypterid diversity are also observed in fossil deposits where other species of Slimonia have been found. S. acuminata has been found associated with Nanahughmilleria lanceolata , Hardieopterus lanarkensis , Eusarcana obesus , Parastylonurus sigmoidalis , Carcinosoma scorpionis and Erettopterus bilobus [19] [20] and S. stylops have been found associated with Nanahughmilleria pygmaea , Eusarcana salteri , Hardieopterus megalops , Erettopterus brodiei , E. gigas, Hughmilleria banksi , Eurypterus cephalaspis and Pterygotus ludensis . [21]

The living environment of the pterygotids differed from genus to genus, with some (such as Pterygotus ) being found in estuaries, while other (such as Jaekelopterus ) were found in freshwater environments; Slimonia has been found in environments which appear to have been intertidal to marine, Patrick Burn Formation for example is estimated to be non-marine or marginal marine [22] or just marine [23] environment. Slimonia likely preyed on smaller fish, as it lacked the enlarged cheliceral claws of the pterygotids and was smaller in size than the largest members of that group. Prey likely included jawless fish such as heterostracans and early osteostracans, which Slimonia would have seized with its frontal appendages. Slimonia traversed its living environment on spindly legs or through using its swimming appendages. The lungs of the genus were located on the underside of the body in a series of folds. [24]

Like many eurypterid species, Slimonia acuminata requires a modern re-description to properly establish defining traits and characteristics. Some traits that appear to be unique to S. acuminata have been described based on specimens housed at the Doncaster Museum and Art Gallery, including rows of pustules (bulges) along the marginal rim of the body and appendages. In some arthropods, pustules serve as attachment points of setae (bristle- or hair-like structures with sensory functions). Similar pustule rows have been discovered in the other eurypterid Drepanopterus abonensis , a sweep-feeder that used the marginal rim to search the substrate of its living environment for prey. If the pustules of S. acuminata had setae, these pustules may have functioned as tactile and sensory organs used for locating and identifying prey, together with the pedipalps (the gracile second pair of appendages, behind the chelicerae). [25]

See also

Related Research Articles

<span class="mw-page-title-main">Eurypterid</span> Order of arthropods (fossil)

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.

<i>Eurypterus</i> Extinct genus of sea scorpions

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.

<i>Pterygotus</i> Extinct genus of eurypterid

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.

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

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 period in Scotland, Ireland, the Czech Republic and South Africa. The type species, H. scouleri, was first named as a species of the significantly different Eurypterus by Samuel Hibbert in 1836. The generic name Hibbertopterus, coined more than a century later, combines his name and the Greek word πτερόν (pteron) meaning "wing".

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

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.

<i>Hughmilleria</i> Genus of extinct arthropods

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.

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

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".

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.

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

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".

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

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.

<span class="mw-page-title-main">Pterygotidae</span> Extinct family of eurypterids

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.

<span class="mw-page-title-main">Carcinosomatidae</span> Extinct family of arthropods

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.

<span class="mw-page-title-main">Pterygotioidea</span> Extinct superfamily of eurypterids

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.

<span class="mw-page-title-main">Mycteropoidea</span> Extinct superfamily of arthropods

Mycteropoidea is an extinct superfamily of eurypterids, an extinct group of chelicerate arthropods commonly known as "sea scorpions". It is one of four superfamilies classified as part of the suborder Stylonurina. Mycteropoids have been recovered from Europe, Russia, South America and South Africa. Mycteropoid specimens are often fragmentary, making it difficult to establish relationships between the included taxa. Only two mycteropoid taxa are known from reasonable complete remains, Hibbertopterus scouleri and H. wittebergensis.

<span class="mw-page-title-main">Hughmilleriidae</span> Extinct family of eurypterids

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.

<span class="mw-page-title-main">Slimonidae</span> Extinct family of eurypterids

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.

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

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>Ciurcopterus</i> Extinct genus of arthropods

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.

<span class="mw-page-title-main">Timeline of eurypterid research</span>

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

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  9. ↑ Lamont, Archie (1955-01-01). "Scottish Silurian Chelicerata". Transactions of the Edinburgh Geological Society. 16 (2): 200–216. doi:10.1144/transed.16.2.200. ISSN   0371-6260. S2CID   131492354.
  10. ↑ Kjellesvig-Waering, Erik N. (1961). "The Silurian Eurypterida of the Welsh Borderland". Journal of Paleontology. 35 (4): 789–835. JSTOR   1301214.
  11. 1 2 3 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).
  12. ↑ Kjellesvig-Waering, Erik N. (1973). "A new Silurian Slimonia (Eurypterida) from Bolivia". Journal of Paleontology . 47 (3): 549–550. JSTOR   1303202.
  13. ↑ 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.
  14. ↑ 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.
  15. ↑ O. Erik Tetlie (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.
  16. ↑ "A killer tail spine likely helped this ancient sea scorpion subdue its prey". Science | AAAS. 2017-04-17. Retrieved 2018-03-18.
  17. ↑ James C. Lamsdell; David J. Marshall; Derek E. G. Briggs (2018). "Hit and Miss: (A Comment on Persons and Acorn, "A Sea Scorpion's Strike: New Evidence of Extreme Lateral Flexibility in the Opisthosoma of Eurypterids")". The American Naturalist. 191 (3): 352–354. doi:10.1086/695955. S2CID   90575897.
  18. 1 2 McCoy, Victoria E.; Lamsdell, James C.; Poschmann, Markus; Anderson, Ross P.; Briggs, Derek E. G. (2015-08-01). "All the better to see you with: eyes and claws reveal the evolution of divergent ecological roles in giant pterygotid eurypterids". Biology Letters. 11 (8): 20150564. doi:10.1098/rsbl.2015.0564. PMC   4571687 . PMID   26289442.
  19. ↑ "Eurypterid-Associated Biota of the Patrick Burn Fm., Lesmahagow (Siltstones) (Silurian to of the United Kingdom) - Fossilworks". fossilworks.org. Retrieved 17 December 2021.
  20. ↑ "Eurypterid-Associated Biota of the Kip Burn Fm., Lesmahagow, Scotland (Silurian to of the United Kingdom) - Fossilworks". fossilworks.org. Retrieved 17 December 2021.
  21. ↑ "Eurypterid-Associated Biota, Platyschisma Beds, Downton Castle Sst., Herefordsh. (Silurian of the United Kingdom) - Fossilworks". fossilworks.org. Retrieved 17 December 2021.
  22. ↑ Tetlie, O. Erik; Braddy, Simon J. (2003). "The first Silurian chasmataspid, Loganamaraspis dunlopi gen. et sp. nov. (Chelicerata: Chasmataspidida) from Lesmahagow, Scotland, and its implications for eurypterid phylogeny" . Earth and Environmental Science Transactions of the Royal Society of Edinburgh. 94 (3): 227–234. doi:10.1017/S0263593300000638. ISSN   1473-7116. S2CID   73596575.
  23. ↑ Bicknell, Russell D. C.; Pates, Stephen (2020). "Pictorial Atlas of Fossil and Extant Horseshoe Crabs, With Focus on Xiphosurida". Frontiers in Earth Science. 8: 98. Bibcode:2020FrEaS...8...98B. doi: 10.3389/feart.2020.00098 . ISSN   2296-6463.
  24. ↑ Fortey, Richard A. (1998). Life: A Natural History of the First Four Billion Years of Life on Earth. New York: Alfred A. Knopf. pp.  146–7. ISBN   978-0-375-40119-0.
  25. ↑ Lomax, Dean; Lamsdell, James; Ciurca, Samuel (2011-01-01). "A collection of eurypterids from the Silurian of Lesmahagow collected pre 1900". Geological Curator. 9 (6): 331–348. doi: 10.55468/GC75 . S2CID   251123684.
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