Campylocephalus
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''Campylocephalus'' is a genus of
eurypterid Eurypterids, often informally called sea scorpions, are a group of extinct marine arthropods that form the Order (biology), order Eurypterida. The earliest known eurypterids date to the Darriwilian stage of the Ordovician period, 467.3 Myr, mil ...
, a group of extinct aquatic
arthropod Arthropods ( ) are invertebrates in the phylum Arthropoda. They possess an arthropod exoskeleton, exoskeleton with a cuticle made of chitin, often Mineralization (biology), mineralised with calcium carbonate, a body with differentiated (Metam ...
s. Fossils of ''Campylocephalus'' have been discovered in deposits ranging from the
Carboniferous The Carboniferous ( ) is a Geologic time scale, geologic period and System (stratigraphy), system of the Paleozoic era (geology), era that spans 60 million years, from the end of the Devonian Period Ma (million years ago) to the beginning of the ...
period in the
Czech Republic The Czech Republic, also known as Czechia, and historically known as Bohemia, is a landlocked country in Central Europe. The country is bordered by Austria to the south, Germany to the west, Poland to the northeast, and Slovakia to the south ...
(the species ''C. salmi'') to the
Permian The Permian ( ) is a geologic period and System (stratigraphy), stratigraphic system which spans 47 million years, from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.902 Mya. It is the s ...
period of
Russia Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...
(species ''C. oculatus'' and ''C. permianus''). The generic name is composed of the
Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...
words καμπύλος (''kampýlos''), meaning "curved", and κεφαλή (''kephalē''), meaning "head". It was a member of the
hibbertopterid Hibbertopteridae (the name deriving from the type genus ''Hibbertopterus'', meaning "Samuel Hibbert-Ware, Hibbert's wing") is a family of Eurypterid, eurypterids, an extinct group of aquatic Arthropod, arthropods. They were members of the superfam ...
family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...
of eurypterids and probably looked much the same as the other members of the family, ''
Hibbertopterus ''Hibbertopterus'' is a genus of eurypterid, a group of extinct marine arthropods. Fossils of ''Hibbertopterus'' have been discovered in deposits ranging from the Devonian period in Belgium, Scotland and the United States to the Carboniferous pe ...
'' and '' Vernonopterus'', in that it was a large, broad and heavy animal quite different from the famous swimming eurypterids (such as ''
Pterygotus ''Pterygotus'' is an extinct 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 s ...
'' and ''
Eurypterus ''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 ...
'') which had been common during earlier periods. Like all other stylonurine eurypterids, ''Campylocephalus'' completely lacked swimming paddles. Hibbertopterids such as ''Campylocephalus'' were, as many other families within the stylonurine
suborder Order () is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and recognized ...
, sweep-feeders. Sweep-feeding food strategies involve specialized
appendages An appendage (or outgrowth) is an external body part or natural prolongation that protrudes from an organism's body such as an arm or a leg. Protrusions from single-celled bacteria and archaea are known as cell-surface appendages or surface app ...
with blades that could be used by the animals to rake through the
substrate Substrate may refer to: Physical layers *Substrate (biology), the natural environment in which an organism lives, or the surface or medium on which an organism grows or is attached ** Substrate (aquatic environment), the earthy material that exi ...
of their living environments in search for small prey items. The species ''C. permianus'', known from deposits of
Late Permian Late or LATE may refer to: Everyday usage * Tardy, or late, not being on time * Late (or the late) may refer to a person who is dead Music * ''Late'' (The 77s album), 2000 * Late (Alvin Batiste album), 1993 * Late!, a pseudonym used by Dave Groh ...
age in Russia, is the only species of ''Campylocephalus'' preserved well enough to allow for size estimates, published estimates putting its size at potentially 1.4 metres (4.6 feet) in length. This species was among the last known surviving eurypterid, living just before or during the
Permian–Triassic extinction event The Permian–Triassic extinction event (also known as the P–T extinction event, the Late Permian extinction event, the Latest Permian extinction event, the End-Permian extinction event, and colloquially as the Great Dying,) was an extinction ...
251.9 million years ago. Before the extinction event, eurypterids had been declining in numbers and diversity for millions of years; ''Campylocephalus'' had been the only known genus of living eurypterids for more than 20 million years since the extinction of the related genus '' Hastimima''.


Description

Classified as a member of the
hibbertopterid Hibbertopteridae (the name deriving from the type genus ''Hibbertopterus'', meaning "Samuel Hibbert-Ware, Hibbert's wing") is a family of Eurypterid, eurypterids, an extinct group of aquatic Arthropod, arthropods. They were members of the superfam ...
family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...
of
eurypterid Eurypterids, often informally called sea scorpions, are a group of extinct marine arthropods that form the Order (biology), order Eurypterida. The earliest known eurypterids date to the Darriwilian stage of the Ordovician period, 467.3 Myr, mil ...
s, ''Campylocephalus'' was overall similar to the other members of the family. It was a large, broad and heavy creature quite unlike most earlier and more famous swimming eurypterids such as ''
Pterygotus ''Pterygotus'' is an extinct 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 s ...
'' and ''
Eurypterus ''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 ...
''. As a member of the stylonurine
suborder Order () is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and recognized ...
, ''Campylocephalus'' completely lacked swimming paddles. Several distinguishing features separate ''Campylocephalus'' from other genera in its family, in particular from the closely related ''
Hibbertopterus ''Hibbertopterus'' is a genus of eurypterid, a group of extinct marine arthropods. Fossils of ''Hibbertopterus'' have been discovered in deposits ranging from the Devonian period in Belgium, Scotland and the United States to the Carboniferous pe ...
''. ''Campylocephalus'' had a subelliptical (almost elliptical)
prosoma The cephalothorax, also called prosoma in some groups, is a tagma of various arthropods, comprising the head and the thorax fused together, as distinct from the abdomen behind. (The terms ''prosoma'' and ''opisthosoma'' are equivalent to ''cepha ...
(head), which was subsemicircular (almost shaped like a
semicircle In mathematics (and more specifically geometry), a semicircle is a one-dimensional locus of points that forms half of a circle. It is a circular arc that measures 180° (equivalently, radians, or a half-turn). It only has one line of symmetr ...
) and strongly convex, being at its broadest in the midsection. The
compound eyes A compound eye is a visual organ found in arthropods such as insects and crustaceans. It may consist of thousands of ommatidia, which are tiny independent photoreception units that consist of a cornea, lens, and photoreceptor cells which distin ...
of ''Campylocephalus'' were laterally placed (on the sides of the head) and were separated from each other by inflated lobes in the middle. Behind the eyes on the
carapace A carapace is a dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tortoises, the unde ...
(the
exoskeleton An exoskeleton () . is a skeleton that is on the exterior of an animal in the form of hardened integument, which both supports the body's shape and protects the internal organs, in contrast to an internal endoskeleton (e.g. human skeleton, that ...
segment covering the head) there were some further lobe-like structures referred to as palpebral lobes. As with the prosoma, the tergites (segments on the upper side of the body) of the abdomen were convex in shape, and possessed
articular processes The articular process or zygapophysis ( + apophysis) of a vertebra is a projection of the vertebra that serves the purpose of fitting with an adjacent vertebra. The actual region of contact is called the ''articular facet''.Moore, Keith L. et al. ...
(projecting structures that helped the segments to fit together). The
appendages An appendage (or outgrowth) is an external body part or natural prolongation that protrudes from an organism's body such as an arm or a leg. Protrusions from single-celled bacteria and archaea are known as cell-surface appendages or surface app ...
(limbs) of ''Campylocephalus'' are only very rarely preserved and are as such almost completely unknown. Due to just how incomplete the fossil remains referred to ''Campylocephalus'' are, determining its size is difficult and as of yet, no formal published size estimates exist for either the
type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...
''C. oculatus'' or the species ''C. salmi''. The sole known fossil remains of ''C. permianus'', a massive incomplete carapace, suggests a very large eurypterid, potentially reaching lengths of 1.4 metres (4.6 feet). In ''C. oculatus'', the eyes were semilunar in shape (almost moon-shaped) and placed near the middle of the carapace, with small
ocelli A simple eye or ocellus (sometimes called a pigment pit) is a form of eye or an optical arrangement which has a single lens without the sort of elaborate retina that occurs in most vertebrates. These eyes are called "simple" to distinguish the ...
(light-sensitive simple eyes) between them. Its carapace had small irregular prominences, a rounded
anterior Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...
edge and an indented posterior edge. The thoracic segments (segments of the
thorax The thorax (: thoraces or thoraxes) or chest is a part of the anatomy of mammals and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main di ...
) of the species were straight and narrow. The eyes of ''C. salmi'' were similar, being placed very close together. The eyes were also a distinguishing feature in ''C. permianus'', where they were placed more posteriorly than in the other species.


History of research

Fossils today recognized as belonging to ''Campylocephalus'' were first described in 1838 as belonging to a species of the genus ''
Limulus ''Limulus'' is a genus of horseshoe crab, with one extant species, the Atlantic horseshoe crab (''Limulus polyphemus''). One fossil species is currently assigned to the genus though several other species have been named, which have since been a ...
'', the same genus as the modern
atlantic horseshoe crab The Atlantic horseshoe crab (''Limulus polyphemus''), also known as the American horseshoe crab, is a species of horseshoe crab, a kind of marine biology, marine and Brackish water, brackish chelicerate arthropod. It is found in the Gulf of Mexic ...
, by Russian paleontologist Stepan S. Kutorga. Citing similarities with members of the modern genus in the appearance and anatomy of the somewhat incomplete fossil, Kutorga named it ''Limulus oculatus''. Scottish naturalist John Scouler described the genus ''Eidothea'' in 1831 based on a single fossil prosoma from
Scotland Scotland is a Countries of the United Kingdom, country that is part of the United Kingdom. It contains nearly one-third of the United Kingdom's land area, consisting of the northern part of the island of Great Britain and more than 790 adjac ...
, but did not grant it any
specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...
. Creating a genus with no species goes against orthodox zoological nomenclature, specifically conflicting for instance with Opinion 65 of the
International Commission on Zoological Nomenclature The International Commission on Zoological Nomenclature (ICZN) is an organization dedicated to "achieving stability and sense in the scientific naming of animals". Founded in 1895, it currently comprises 26 commissioners from 20 countries. Orga ...
; Any taxonomical difficulties implied with Scouler's designation were easily avoided, however, by the discovery that the genus name was preoccupied by a genus of molluscs described in 1826. Nevertheless, the name ''Eidothea'' would be associated with the Scottish eurypterid species ''Eurypterus scouleri'', with a near identical prosoma, described in 1836. In 1860 French paleontologist Edouard D'Eichwald recognized that the carapace and thoracic segments which had been described by Kutorga were quite distinct from ''Limulus'', and thus a new genus was named to contain ''Limulus oculatus'', dubbed by D'Eichwald as ''Campylocephalus''. This generic name is composed of the
Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...
words καμπύλος (''kampýlos''), meaning "curved", and κεφαλή (''kephalē''), meaning "head". The second species of ''Campylocephalus'' to be described, ''C. salmi'', was named as a species of the quite distantly related ''Eurypterus'' by the Slovak geologist and paleontologist Dionýs Štúr in 1877. Štúr's description was based on two incomplete fossil carapaces. The first fragmentary carapace only preserved the lower part of the head, ending in two pointed and concave arches. The eyes of this carapace were close together, in the middle of the carapace, and on a triangularly shaped elevated portion similar to some specimens of the related ''Hibbertopterus scouleri''. In the second carapace specimen, the carapace began to stretch forward above the eyes. Both of these fossils also possessed protuberances of different sizes across the exoskeleton, showing vague forms and shapes not seen in other specimens of the genus. Fossils of ''Eurypterus scouleri'' were compared to the carapace described by Kutorga in 1838 by Norwegian paleontologist Leif Størmer in 1951, who concluded that the two were clearly congeneric. At this point, D'Eichwald had already recognized the fossils designated as "''Eidothea''" by Scouler as representatives of ''Campylocephalus''. As such, ''E. scouleri'' was classified as ''Campylocephalus scouleri''. Though the legs of ''Campylocephalus'' were still unknown at the time, even with the addition of the Scottish species, any grouping with other genera would have to be made using features of the carapace. Comparing the ornamentation of the carapace to other eurypterids, Størmer found it to be similar to the genus '' Tarsopterella'' (where the legs were also more or less unknown) which allowed ''Campylocephalus'' to be firmly placed within the family Stylonuridae (which would later be raised to become the suborder Stylonurina, not to be confused with the presently recognized eurypterid family Stylonuridae). English paleontologist Charles D. Waterston was the first to suggest that ''C. scouleri'' perhaps shouldn't be considered as congeneric with ''Campylocephalus'', raising the issue in a 1958 paper. He posited that though the
dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage The fus ...
anatomy of the prosoma was quite similar between ''C. scouleri'' and ''C. oculatus'', the designated type species, multiple well-preserved fossils had allowed for detailed research into the
ventral Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...
anatomy and appendages of ''C. scouleri'' since the two had been placed in the same genus, whilst the ventral anatomy and appendages of ''C. oculatus'' remained unknown. A year later, in 1959, American paleontologist Erik Norman Kjellesvig-Waering created the new genus ''Hibbertopterus'' to contain ''C. scouleri'' (now ''Hibbertopterus scouleri'') and placed both genera within the family Hibbertopteridae. Described by Russian paleontologist Alexey G. Ponomarenko in 1985, ''C. permianus'' was originally named as a species of ''Hibbertopterus''. The only known specimen of this species is the holotype, PIN N1209/2, an incomplete carapace, but Ponomarenko could list several features that distinguished it from other species referred to ''Hibbertopterus''. Among these were most prominently the posterior position of the lateral eyes and said eyes not being circular in shape. In 2012, American paleontologist James C. Lamsdell could demonstrate that these unique features were actually diagnostic features of the genus ''Campylocephalus'' and thus reclassified it as its current combination. Though Ponomarenko had mentioned several features that also distinguished ''C. permianus'' from the then currently recognized species of ''Campylocephalus'', including a different carapace shape and some thickening of the exoskeleton around the eyes, Lamsdell determined that these distinctions were not valid. In the view of Lamsdell, specimens of the type species ''C. oculatus'' are not well preserved enough to determine the precise structure of the eyes and because fossils of its carapace are either flattened or incomplete, its shape can not be ascertained with complete accuracy.


Classification

''Campylocephalus'' is classified as part of the family Hibbertopteridae, a family of eurypterids within the superfamily Mycteropoidea, alongside the genera ''Hibbertopterus'' and '' Vernonopterus''. The genus contains three species; ''C. oculatus'' and ''C. permianus'' from the
Permian The Permian ( ) is a geologic period and System (stratigraphy), stratigraphic system which spans 47 million years, from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.902 Mya. It is the s ...
of
Russia Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...
and ''C. salmi'' from the
Carboniferous The Carboniferous ( ) is a Geologic time scale, geologic period and System (stratigraphy), system of the Paleozoic era (geology), era that spans 60 million years, from the end of the Devonian Period Ma (million years ago) to the beginning of the ...
of the
Czech Republic The Czech Republic, also known as Czechia, and historically known as Bohemia, is a landlocked country in Central Europe. The country is bordered by Austria to the south, Germany to the west, Poland to the northeast, and Slovakia to the south ...
. The classification of ''C. salmi'' is considered somewhat uncertain,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). with ''C. salmi'' being fragmentary (as all other species of the genus) and possessing some unique features (e.g. the differently sized protuberances around the carapace). The hibbertopterids are united as a group by being large mycteropoids with broad prosomas, a hastate (e.g. shaped like a ''
gladius ''Gladius'' () is a Latin word properly referring to the type of sword that was used by Ancient Rome, ancient Roman foot soldiers starting from the 3rd century BC and until the 3rd century AD. Linguistically, within Latin, the word also came t ...
'', a
Roman Roman or Romans most often refers to: *Rome, the capital city of Italy *Ancient Rome, Roman civilization from 8th century BC to 5th century AD *Roman people, the people of Roman civilization *Epistle to the Romans, shortened to Romans, a letter w ...
sword)
telson The telson () is the hindmost division of the body of an arthropod. Depending on the definition, the telson is either considered to be the final segment (biology), segment of the arthropod body, or an additional division that is not a true segm ...
(which was the posteriormost division of the body) with paired keels on the ventral side, ornamentation consisting of scales or other similar structures on the exoskeleton, the fourth pair of appendages possessing spines, the more posterior tergites of the abdomen possessing tongue-shaped scales near their edges and there being lobes positioned posterolaterally (posteriorly on both sides) on the prosoma. The features of ''Campylocephalus'' and ''Vernonopterus'' makes it clear that both genera represent hibbertopterid eurypterids, but the incomplete nature of all fossil specimens referred to them make any further study of the precise
phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...
relationships within the Hibbertopteridae difficult. Both genera could even represent synonyms of ''Hibbertopterus'' itself, though the highly incomplete nature of their remains again makes that hypothesis impossible to confirm. The cladogram below is adapted from Lamsdell (2012), collapsed to only show the superfamily Mycteropoidea.


Paleoecology

Hibbertopterids such as ''Campylocephalus'' were sweep-feeders, having modified spines on their forward-facing prosomal appendages that allowed them to rake through the
substrate Substrate may refer to: Physical layers *Substrate (biology), the natural environment in which an organism lives, or the surface or medium on which an organism grows or is attached ** Substrate (aquatic environment), the earthy material that exi ...
of their living environments. Though sweep-feeding was used as a strategy by many genera within the Stylonurina, it was most developed within the hibbertopterids, which possessed blades on the second, third and fourth pair of appendages. Some species of the closely related ''Hibbertopterus'' had specialized comb-like
rachis In biology, a rachis (from the [], "backbone, spine") is a main axis or "shaft". In zoology and microbiology In vertebrates, ''rachis'' can refer to the series of articulated vertebrae, which encase the spinal cord. In this case the ''rachi ...
(shafts) that were able to entrap small prey and other organic food particles. Though they would have been slow owing to their massive size and robust form, studies on ''Hibbertopterus'' footprints discovered in Scotland have demonstrated that hibbertopterids would have been able to walk on land for at least short periods of time. The tracks discovered indicate that they would have utilized a lumbering, jerking and dragging movement and that the keeled belly and the telson left a central groove behind. Some studies suggest that eurypterids possessed a dual respiratory system, which would have allowed for this kind of occasional terrestrial movement. ''C. salmi'' is known from the Ostrava Formation of the Czech Republic and would have lived during the Arnsbergian age (326.4–318.1 million years ago) of the Carboniferous period. The deposits were the eurypterid fossils were found are
lacustrine A lake is often a naturally occurring, relatively large and fixed body of water on or near the Earth's surface. It is localized in a basin or interconnected basins surrounded by dry land. Lakes lie completely on land and are separate from t ...
, meaning that they formed on the bottom of an ancient lake. Spiders of the genus ''
Eophrynus ''Eophrynus'' is an extinct genus of arachnids from the extinct order Trigonotarbida, which lived during the Late Carboniferous period in Europe. The genus was first described in 1871 by Henry Woodward (geologist). The name comes from ''Eo'', me ...
'', part of the extinct
arachnid Arachnids are arthropods in the Class (biology), class Arachnida () of the subphylum Chelicerata. Arachnida includes, among others, spiders, scorpions, ticks, mites, pseudoscorpions, opiliones, harvestmen, Solifugae, camel spiders, Amblypygi, wh ...
order Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood ...
Trigonotarbida The order Trigonotarbida is a group of extinct arachnids whose fossil record extends from the late Silurian to the early Permian ( Pridoli to Sakmarian).Dunlop, J. A., Penney, D. & Jekel, D. 2020A summary list of fossil spiders and their relative ...
, are known from the same location and age, and numerous
anthozoa Anthozoa is one of the three subphyla of Cnidaria, along with Medusozoa and Endocnidozoa. It includes Sessility (motility), sessile marine invertebrates and invertebrates of brackish water, such as sea anemones, Scleractinia, stony corals, soft c ...
ns (the group that contains animals such as
coral Corals are colonial marine invertebrates within the subphylum Anthozoa of the phylum Cnidaria. They typically form compact Colony (biology), colonies of many identical individual polyp (zoology), polyps. Coral species include the important Coral ...
s and
sea anemone Sea anemones ( ) are a group of predation, predatory marine invertebrates constituting the order (biology), order Actiniaria. Because of their colourful appearance, they are named after the ''Anemone'', a terrestrial flowering plant. Sea anemone ...
s) are known from the same age within the Ostrava Formation. It is difficult to make any statements on the paleoecology of the type species, ''C. oculatus'', as the precise location and dating of the fossil specimen remains somewhat unclear. Most accounts place the fossil as having been found at a location named Dourasovo in Russia and being from the
Guadalupian The Guadalupian is the second and middle Series (stratigraphy), series/Epoch (geology), epoch of the Permian. The Guadalupian was preceded by the Cisuralian and followed by the Lopingian. It is named after the Guadalupe Mountains of New Mexico an ...
epoch (272.3–259.8 million years ago) of the Permian period. The species of ''C. permianus'' is one of the latest known surviving eurypterid species. The sole fossil representing the species was discovered in the
Komi Autonomous Soviet Socialist Republic The Komi Autonomous Soviet Socialist Republic (; ), abbreviated as Komi ASSR (Komi and ), was an autonomous republic of the Russian SFSR within the Soviet Union, established in 1936 as successor of Komi-Zyryan Autonomous Oblast. In 1991, it b ...
of the
Soviet Union The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...
(the modern
Komi Republic The Komi Republic (; ), sometimes simply referred to as Komi, is a republics of Russia, republic of Russia situated in the northeast of European Russia. Its capital city, capital is the types of inhabited localities in Russia, city of Syktyvka ...
of Russia) in deposits of approximately the age of the
Permian–Triassic extinction event The Permian–Triassic extinction event (also known as the P–T extinction event, the Late Permian extinction event, the Latest Permian extinction event, the End-Permian extinction event, and colloquially as the Great Dying,) was an extinction ...
251.9 million years ago. In the Permian, Komi would have been a coastal region of the supercontinent
Pangaea Pangaea or Pangea ( ) was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from the earlier continental units of Gondwana, Euramerica and Siberia during the Carboniferous period approximately 335 mi ...
. Though no other fossils of the exact same age have been reported, other Permian-age life known from the region include
bryozoa Bryozoa (also known as the Polyzoa, Ectoprocta or commonly as moss animals) are a phylum of simple, aquatic animal, aquatic invertebrate animals, nearly all living in sedentary Colony (biology), colonies. Typically about long, they have a spe ...
ns and
bivalve Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of aquatic animal, aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed b ...
s. By the beginning of the Permian, the eurypterids were already in decline relative to what their numbers and diversity had once been. The group was one of many heavily affected by the
Late Devonian extinction The Late Devonian mass extinction, also known as the Kellwasser event, was a mass extinction event which occurred around 372 million years ago, at the boundary between the Frasnian and Famennian ages of the Late Devonian period.Racki, 2005McGh ...
, which rendered all but a single genus of eurypterine (those with swimming paddles) eurypterids extinct ('' Adelophthalmus''). Of the 16 eurypterid families that had lived during the beginning of the
Devonian The Devonian ( ) is a period (geology), geologic period and system (stratigraphy), system of the Paleozoic era (geology), era during the Phanerozoic eon (geology), eon, spanning 60.3 million years from the end of the preceding Silurian per ...
period, three families survived and persisted into the Carboniferous period, all of which contained only non-marine species. By the Permian, only four genera were still alive; ''Adelophthalmus'' (a adelophthalmid), '' Hastimima'' and '' Woodwardopterus'' ( mycteroptids), and ''Campylocephalus'' itself. Both ''Adelophthalmus'' and ''Hastimima'' went extinct during the
Early Permian 01 or 01 may refer to: * The year 2001, or any year ending with 01 * The month of January * 1 (number) Music * '01 (Richard Müller album), ''01'' (Richard Müller album), 2001 * 01 (Urban Zakapa album), ''01'' (Urban Zakapa album), 2011 * ''01011 ...
, which left ''Campylocephalus'' as one of only two living genera of eurypterids for more than 20 million years until its own extinction in the Permian–Triassic extinction event. ''Woodwardopterus'' also went extinct around this time.


See also

*
List of eurypterid genera This list of eurypterid genera is a comprehensive listing of all genera that have ever been included in the order Eurypterida, excluding purely vernacular terms. The list includes all commonly accepted genera, but also genera that are now consider ...
*
Timeline of eurypterid research This timeline of eurypterid research is a chronologically ordered list of important fossil discoveries, controversies of interpretation, and Biological taxonomy, taxonomic revisions of eurypterids, a group of extinct aquatic arthropods closely re ...


References

{{Taxonbar, from=Q5028750 Stylonurina Fossils of the Czech Republic Fossils of Russia Permian eurypterids Carboniferous eurypterids Eurypterids of Europe Permian genus extinctions Eurypterids of Asia