Cheiruridae is a family of phacopid

trilobite Trilobites (; meaning "three lobes") are extinct marine arthropods that form the class Trilobita. Trilobites form one of the earliest-known groups of arthropods. The first appearance of trilobites in the fossil record defines the base of the ...

s of the suborder

Cheirurina Cheirurina is a suborder of the trilobite order Phacopida. Known representatives range from the uppermost Cambrian (upper Furongian) to the end of the Middle Devonian (Givetian The Givetian is one of two faunal stages in the Middle Devonian P ...

. Its members, as with other members of the suborder, had distinctive

pygidia The pygidium (plural pygidia) is the posterior body part or shield of crustaceans and some other arthropods, such as insects and the extinct trilobites. In groups other than insects, it contains the anus and, in females, the ovipositor. It is c ...

modified into finger-like spines. They first appeared in the uppermost

Cambrian The Cambrian Period ( ; sometimes symbolized Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million years ag ...

(upper

Furongian The Furongian is the fourth and final epoch and series of the Cambrian. It lasted from to million years ago. It succeeds the Miaolingian series of the Cambrian and precedes the Lower Ordovician Tremadocian Stage. It is subdivided into thre ...

), and persisted until the end of the Middle

Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, w ...

(

Givetian The Givetian is one of two faunal stages in the Middle Devonian Period. It lasted from million years ago to million years ago. It was preceded by the Eifelian Stage and followed by the Frasnian Stage. It is named after the town of Givet in ...

). Currently about 657 species assigned to 99 genera are included.

Distribution

The subfamily Cheirurinae with 269 species in 38 genera occur from the

Floian The Floian is the second stage of the Ordovician Period. It succeeds the Tremadocian with which it forms the Lower Ordovician epoch. It precedes the Dapingian Stage of the Middle Ordovician. The Floian extended from to million years ago. The ...

to the Givetian and are probably

monophyletic In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic ...

. The 109 species in 15 genera of the Acanthoparyphinae are also probably monophyletic, and are known from the

to the

Ludfordian In the geologic timescale, the Ludfordian is the upper of two chronostratigraphic stages within the Ludlow Series. Its age is the late Silurian Period, and within both the Palaeozoic Era and Phanerozoic Eon. The rocks assigned to the Ludfordi ...

. The Cyrtometopinae were present between the Floian and the Upper

Katian The Katian is the second stage of the Upper Ordovician. It is preceded by the Sandbian and succeeded by the Hirnantian Stage. The Katian began million years ago and lasted for about 7.8 million years until the beginning of the Hirnantian million ...

, enveloping 22 species in 5 genera, of which the monophyly is unclear. The Deiphoninae are probably monophyletic, occur from the

Dapingian The Dapingian is the third stage of the Ordovician period and the first stage of the Middle Ordovician series. It is preceded by the Floian and succeeded by the Darriwilian. The top of the Floian is defined as the first appearance of the conodont s ...

to the

Gorstian In the geologic timescale, the Gorstian is an age of the Ludlow Epoch of the Silurian Period of the Paleozoic Era of the Phanerozoic Eon that is comprehended between 427.4 ± 0.5 Ma and 425.6 ± 0.9 Ma (million years ago), approximately. The ...

, having 71 species assigned to 6 genera. The possibly

paraphyletic In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...

Eccoptochilinae with 67 species in 13 genera are known between the Floian and upper Katian. The Heliomerinae are a small monophyletic group with 13 species in 2 genera. The Pilekiinae are the earliest subfamilily and therefore certainly paraphyletic, occurring in the upper

and going extinct in the

Darriwilian The Darriwilian is the upper stage of the Middle Ordovician. It is preceded by the Dapingian and succeeded by the Upper Ordovician Sandbian Stage. The lower boundary of the Darriwilian is defined as the first appearance of the graptolite species ...

with 56 known species assigned to 19 genera. The

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

Sphaerexochinae has about 50 species between the Floian and Přídolí.

Genera

*'' Acanthoparypha'' *'' Actinopeltis'' *'' Anasobella'' *'' Ancyginaspis'' *'' Apollonaspis'' *'' Arcticeraurinella'' *'' Areia'' *'' Areiaspis'' *'' Azyptyx'' *'' Barrandeopeltis'' *'' Borealaspis'' *'' Bornholmaspis'' *'' Bufoceraurus'' *''

Ceraurinella ''Ceraurinella'' is an extinct genus of trilobite Trilobites (; meaning "three lobes") are extinct marine arthropods that form the class Trilobita. Trilobites form one of the earliest-known groups of arthropods. The first appearance of trilo ...

'' *'' Ceraurinium'' *''

Ceraurinus ''Ceraurinus'' is an extinct genus of trilobite in the order Phacopida. It contains one species, ''C. serratus''. External links ''Ceraurinus''at the Paleobiology Database The Paleobiology Database is an online resource for information on the ...

'' *'' Cerauromeros'' *'' Cerauropeltis'' *'' Ceraurus'' *''

Cheirurus ''Cheirurus'' (from Greek ''χείρ, cheir'' meaning "hand" and ''ουρά, oura'' meaning "tail") is a genus of phacopid trilobites that lived from the Ordovician to the Devonian. Its remains have been found in Africa, Asia, Australia, Europ ...

'' (

type genus In biological taxonomy, the type genus is the genus which defines a biological family and the root of the family name. Zoological nomenclature According to the International Code of Zoological Nomenclature, "The name-bearing type of a nomina ...

) *''

Chiozoon ''Chiozoon'' is a cheirurid phacopid trilobite that existed during the lower Silurian The Silurian ( ) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago ( Mya), to the ...

'' *'' Contracheirurus'' *'' Courtessolium'' *'' Crotalocephalides'' *''

Crotalocephalina ''Crotalocephalina'' is an extinct genus of trilobite in the order Phacopida found in Morocco. External links''Photo of a Crotocephalina'Crotalocephalina''at the Paleobiology Database The Paleobiology Database is an online resource for info ...

'' *''

Crotalocephalus ''Crotalocephalus'' is a genus of trilobites that lived from the Late Silurian to the Early Devonian. Its remains have been found in Asia, Australia, Africa, and Europe. References External links ''Crotalocephalus''in the Paleobiology ...

'' *'' Cybelloides'' *''

Cyrtometopus ''Cyrtometopus'' is an extinct genus of trilobite in the order Phacopida. Species * '' Cyrtometopus affinis'' * '' Cyrtometopus clavifrons'' * '' Cyrtometopus meridianus'' * '' Cyrtometopus sembnitzkii'' External links ''Cyrtometopus''at ...

'' *'' Deiphon'' *'' Didrepanon'' *''

Eccoptochile ''Eccoptochile'' is an extinct genus of trilobite in the order Phacopida. It contains one species, ''E. clavigera''. External links ''Eccoptochile''at the Paleobiology Database Cheiruridae Phacopida genera Ordovician trilobites of Euro ...

'' *'' Eccoptochiloides'' *'' Forteyops'' *'' Foulonia'' *'' Gabriceraurus'' *'' Geracephalina'' *'' Hadromeros'' *'' Hammannopyge'' *'' Hapsiceraurus'' *''

Heliomera ''Heliomera'' is an extinct genus of trilobite in the order Phacopida. It contains two species. ''H. albata'' and ''H. sol''. External links ''Heliomera''at the Paleobiology Database Cheiruridae Extinct animals of North America Devonia ...

'' *''

Heliomeroides ''Heliomeroides'' is a trilobite in the order Phacopida (family Cheiruridae), that existed during the upper Ordovician in what is now the United States. It was described by Evitt in 1951, and the type species is ''Heliomeroides teres''. The Type ...

'' *'' Holia'' *'' Hyrokybe'' *'' Junggarella'' *'' Kawina'' *''

Kolymella ''Kolymella'' is an extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, altho ...

'' *'' Krattaspis'' *'' Ktenoura'' *'' Laneites'' *''

Lehua Lehua Island is a small, crescent-shaped island in the Hawaiian islands, north of Niihau, due west of Kauai. The uninhabited, barren island is a tuff cone which is part of the active Niihau volcano. Lehua was one of the first five isla ...

'' *'' Leviceraurus'' *'' Nieszkowskia'' *'' Onycopyge'' *'' Osekaspis'' *'' Pandaspinapyga'' *''

Paraceraurus ''Paraceraurus'' is a genus of trilobites that lived in the Ordovician period (485.4 to 443.4 Ma). Its remains have been found in China, Estonia, Sweden and North America. These trilobites have a rounded and moderately convex ''cephalon''. ' ...

'' *'' Parasphaerexochus'' *'' Parayoungia'' *'' Parisoceraurus'' *'' Pateraspis'' *'' Patomaspis'' *'' Placoparina'' *'' Pompeckia'' *'' Proromma'' *'' Protocerauroides'' *'' Pseudocheirurus'' *'' Pseudosphaerexochus'' *'' Radiurus'' *'' Ratinkaspis'' *'' Reraspis'' *'' Skelipyx'' *''

Sphaerexochus ''Sphaerexochus'' is a genus of trilobite from the Middle Ordovician to Late Silurian (468.1 to 418.7 Ma) of Asia, Australia, Europe, and North America North America is a continent in the Northern Hemisphere and almost entirely ...

'' *'' Sphaerocoryphe'' *'' Stubblefieldia'' *''

Sycophantia ''Sycophantia'' is an extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, alt ...

'' *'' Turantyx'' *'' Valongia'' *'' Whittakerites'' *'' Xylabion'' *'' Xystocrania'' *'' Youngia'' *'' Zazvorkaspis''

References

External links

* Trilobite families Cambrian trilobites Ordovician trilobites Silurian trilobites Devonian trilobites Furongian first appearances Givetian extinctions Paleozoic life of Newfoundland and Labrador {{phacopida-stub