The

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 is a group of 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 ...

s whose

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

record extends from the late

Silurian The Silurian ( ) is a geologic period and system spanning 23.5 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the third and shortest period of t ...

to the early

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 ...

( Pridoli to Sakmarian).Dunlop, J. A., Penney, D. & Jekel, D. 2020
A summary list of fossil spiders and their relatives
In World Spider Catalog. Natural History Museum Bern, online at http://wsc.nmbe.ch , version 20.5 These animals are known from several localities in

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

and

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

, as well as a single record from

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

. Trigonotarbids can be envisaged as

spider Spiders (order (biology), order Araneae) are air-breathing arthropods that have eight limbs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude spider silk, silk. They are the largest order of arachnids and ran ...

-like arachnids, but without silk-producing

spinneret A spinneret is a silk-spinning organ of a spider or the larva of an insect. Some adult insects also have spinnerets, such as those borne on the forelegs of Embioptera. Spinnerets are usually on the underside of a spider's opisthosoma, and ar ...

s. They ranged in size from a few millimetres to a few centimetres in body length and had segmented abdomens (

opisthosoma The opisthosoma is the posterior part of the body in some arthropods, behind the prosoma ( cephalothorax). It is a distinctive feature of the subphylum Chelicerata (arachnids, horseshoe crabs and others). Although it is similar in most respects ...

), with the dorsal exoskeleton ( tergites) across the backs of the animals' abdomens, which were characteristically divided into three or five separate plates. Probably living as predators on other

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, some later trigonotarbid species were quite heavily armoured and protected themselves with spines and tubercles. About seventy species are currently known, with most fossils originating 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 ...

coal measures.

Historical background

The first trigonotarbid was described in 1837 from the coal measures of

Coalbrookdale Coalbrookdale is a town in the Ironbridge Gorge and the Telford and Wrekin borough of Shropshire, England, containing a settlement of great significance in the history of iron ore smelting. It lies within the civil parish called The Gorge, Shro ...

England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It is located on the island of Great Britain, of which it covers about 62%, and List of islands of England, more than 100 smaller adjacent islands. It ...

by the famous English geologist Dean

William Buckland William Buckland Doctor of Divinity, DD, Royal Society, FRS (12 March 1784 – 14 August 1856) was an English theologian, geologist and paleontology, palaeontologist. His work in the early 1820s proved that Kirkdale Cave in North Yorkshire h ...

. He believed it to be a fossil

beetle Beetles are insects that form the Taxonomic rank, order Coleoptera (), in the superorder Holometabola. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 40 ...

and named it ''Curculoides prestvicii''. A much better preserved example was later discovered from Coseley near

Dudley Dudley ( , ) is a market town in the West Midlands, England, southeast of Wolverhampton and northwest of Birmingham. Historically part of Worcestershire, the town is the administrative centre of the Metropolitan Borough of Dudley. In the ...

; also in the English

West Midlands conurbation The West Midlands conurbation is the large conurbation in the West Midlands region of England. The area consists of two cities and numerous towns: to the east, the city of Birmingham, along with adjacent towns of Solihull and Sutton Coldfield; a ...

. Described in 1871 by Henry Woodward, he correctly identified it as an arachnid and renamed it '' Eophrynus prestvicii''—whereby the genus name comes from (', meaning 'dawn'), and '' Phrynus'', a genus of living whip spider (

Amblypygi Amblypygi is an order of arachnids also known as whip-spiders or tailless whip-scorpions, not to be confused with whip-scorpions or vinegaroons that belong to the related order Thelyphonida. The name "amblypygid" means "blunt tail", a referen ...

). Woodward subsequently described another trigonotarbid, ''Brachypyge carbonis'', from the coal measures of

Mons Mons commonly refers to: * Mons, Belgium, a city in Belgium * Mons pubis (mons Venus or mons veneris), in mammalian anatomy, the adipose tissue lying above the pubic bone * Mons (planetary nomenclature), a sizable extraterrestrial mountain * Batt ...

Belgium Belgium, officially the Kingdom of Belgium, is a country in Northwestern Europe. Situated in a coastal lowland region known as the Low Countries, it is bordered by the Netherlands to the north, Germany to the east, Luxembourg to the southeas ...

; although this fossil is known only from its abdomen and was initially mistaken for those of a

crab Crabs are decapod crustaceans of the infraorder Brachyura (meaning "short tailed" in Greek language, Greek), which typically have a very short projecting tail-like abdomen#Arthropoda, abdomen, usually hidden entirely under the Thorax (arthropo ...

A new arachnid order

In 1882, the German

zoologist Zoology ( , ) is the scientific study of animals. Its studies include the structure, embryology, classification, habits, and distribution of all animals, both living and extinct, and how they interact with their ecosystems. Zoology is one ...

Ferdinand Karsch described a number of fossil arachnids from the coal measures of Neurode in

Silesia Silesia (see names #Etymology, below) is a historical region of Central Europe that lies mostly within Poland, with small parts in the Czech Silesia, Czech Republic and Germany. Its area is approximately , and the population is estimated at 8, ...

(now

Poland Poland, officially the Republic of Poland, is a country in Central Europe. It extends from the Baltic Sea in the north to the Sudetes and Carpathian Mountains in the south, bordered by Lithuania and Russia to the northeast, Belarus and Ukrai ...

), including one he named ''Anthracomartus voelkelianus'' in honour of Herr Völkel, the foreman of the mine where it was discovered. This species was raised to a new, extinct, arachnid order which Karsch called Anthracomarti. The name is derived from ('), the Greek word for

coal Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other Chemical element, elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal i ...

. A number of other fossils which would eventually be placed in Trigonotarbida were discovered around this time. Hanns Bruno Geinitz described ''Kreischeria wiedei'' from the coal measures of

Zwickau Zwickau (; ) is the fourth-largest city of Saxony, Germany, after Leipzig, Dresden and Chemnitz, with around 88,000 inhabitants,. The West Saxon city is situated in the valley of the Zwickau Mulde (German: ''Zwickauer Mulde''; progression: ), ...

Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...

, although he interpreted it as a fossil

pseudoscorpion Pseudoscorpions, also known as false scorpions or book scorpions, are small, scorpion-like arachnids belonging to the order Pseudoscorpiones, also known as Pseudoscorpionida or Chelonethida. Pseudoscorpions are generally beneficial to humans bec ...

. Johann Kušta described ''Anthracomartus krejcii'' from Rakovník 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 ...

, and published further descriptions in a number of subsequent papers. In 1884,

Samuel Hubbard Scudder Samuel Hubbard Scudder (April 13, 1837 – May 17, 1911) was an American entomologist and paleontologist. He was a leading figure in entomology during his lifetime and the founder of insect paleontology in America. In addition to fossil insects, ...

described ''Anthracomartus trilobitus'' from

Fayetteville, Arkansas Fayetteville ( ) is the List of cities and towns in Arkansas, second-most populous city in the U.S. state of Arkansas, the county seat of Washington County, Arkansas, Washington County, and the most populous city in Northwest Arkansas. The city ...

—the first trigonotarbid from

Relationships

Early studies tended to confuse trigonotarbids with other living or extinct groups of arachnids; particularly harvestmen (

Opiliones The Opiliones (formerly Phalangida) are an Order (biology), order of arachnids, Common name, colloquially known as harvestmen, harvesters, harvest spiders, or daddy longlegs (see below). , over 6,650 species of harvestmen have been discovered w ...

). Petrunkevitch's division of the trigonotarbids into two, unrelated, orders was noted above. In detail, he divided the arachnids into suborders based on the width of the division between the two parts of the body (the

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 ...

and

). Anthracomartida and another extinct order, Haptopoda, were grouped into a subclass Stethostomata defined by a broad division of the body and downward-hanging mouthparts. Trigonotarbida was placed in its own subclass Soluta and defined as having a division of the body which was variable in width. Petrunkevitch's scheme was largely followed in subsequent studies of fossil arachnids.

Pantetrapulmonata

In the 1980s, Bill Shear and colleagues carried out an important study on well preserved Mid Devonian trigonotarbids from Gilboa, New York. They questioned whether it was appropriate to define a group of animals on a variable character state and carried out the first

cladistic Cladistics ( ; from Ancient Greek 'branch') is an approach to biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is ...

analysis of fossil and living arachnids. They showed that trigonotarbids are closely related to a group of arachnids which have gone under various names (Caulogastra, Arachnidea, ''etc.''), but for which the name

Tetrapulmonata Tetrapulmonata is a Taxonomic rank, non-ranked Order (biology), supra-ordinal clade of arachnids. It is composed of the Extant taxon, extant orders Uropygi (whip scorpions), Schizomida (short-tailed whip scorpions), Amblypygi (tail-less whip scor ...

has become most widespread. Members of the Tetrapulmonata include

s ( Araneae), whip spiders (

), whip scorpions (

Uropygi Uropygi is an arachnid order comprising invertebrates commonly known as whip scorpions or vinegaroons (also spelled vinegarroons and vinegarones). They are often called uropygids. The name "whip scorpion" refers to their resemblance to scorpion ...

) and shorttailed whipscorpion (

Schizomida Schizomida, also known as sprickets or short-tailed whip-scorpions, is an order of arachnids, generally less than in length. The order is not yet widely studied. E. O. Wilson has identified schizomids as among the "groups of organisms that des ...

) and, together with trigonotarbids, share characters like two pairs of book lungs and similar mouthparts with fangs operating rather like a pocket knife. In a 2007 study of arachnid relationships, the Shear ''et al.'' hypothesis was largely supported and a group Pantetrapulmonata was proposed which comprises Trigonotarbida + Tetrapulmonata. This has since been corroborated in more recent cladistic analyses.

Trigonotarbids and ricinuleids

In 1892, Ferdinand Karsch suggested that the rare and rather bizarre-looking ricinuleids ( Ricinulei) were the last living descendants of the trigonotarbids. A similar hypothesis was reintroduced by Dunlop, who pointed out distinct similarities and possible

sister group In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

relationship between these arachnid groups. Both have opisthosomal tergites divided into median and lateral plates and both have a complicated coupling mechanism between the prosoma and the opisthosoma which 'locks' the two halves of the body together. Although cladistic analysis has tended to recover ricinuleids in their traditional position closely related to mites and ticks, further discoveries have revealed that the tip of the pedipalp ends in a small claw in both trigonotarbids and ricinuleids. If the hypothesis is true, ricinuleids, despite the lack of tetrapulmonate key characters (e.g. book lungs), may represent part of the pantetrapulmonate clade alongside trigonotarbids as well.

Internal relationships

The first cladistic analysis of the trigonotarbids was published in 2014. This recovered the families Anthracomartidae, Anthracosironidae, and Eophrynidae as monophyletic. In contrast Trigonotarbidae, Aphantomartidae, Palaeocharinidae, and Kreischeriidae were not. Two clades were consistently recovered with strong support—('' Palaeocharinus'' (Archaeomartidae + Anthracomartidae)), and '' Lissomartus'' as sister group the 'eophrynid assemblage' ('' Aphantomartus'' ('' Alkenia'' ('' Pseudokreischeria'' ('' Kreischeria'' ('' Eophrynus'' + '' Pleophrynus''))))).

Description

20201108 Trigonotarbida dorsal ventral morphology

20201109 Trigonotarbida sagittal external morphology

Trigonotarbids superficially resemble

s, but can be easily recognised by having tergites on the dorsal side of the opisthosoma divided into median and lateral plates. This character is shared with ricinuleids ( Ricinulei) (see also Ricinulei#Relationships). As in other arachnids, the body is divided into a

(or cephalothorax) and

(or abdomen). Body length ranges from a couple of millimetres up to about .

Prosoma

The prosoma is covered by 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 ...

and always bears a pair of median eyes. In the probably basal families Palaeocharinidae, Anthracomartidae—and perhaps also Anthracosironidae—there is an additional pair of lateral eye tubercles which, at least in palaeocharinids, appear to have borne a series of individual lenses. In this sense palaeocharinids seem to be in the process of reducing a

compound eye A compound eye is a Eye, visual organ found in arthropods such as insects and crustaceans. It may consist of thousands of ommatidium, ommatidia, which are tiny independent photoreception units that consist of a cornea, lens (anatomy), lens, and p ...

. Anterior margin of the carapace protrude into a projection referred to as clypeus. The

chelicerae The chelicerae () are the arthropod mouthparts, mouthparts of the subphylum Chelicerata, an arthropod group that includes arachnids, horseshoe crabs, and sea spiders. Commonly referred to as "jaws", chelicerae may be shaped as either articulated ...

are of the "pocket-knife" type consisting of a basal segment and a sharp, curving fang. The chelicerae are described as ''paleognathic'': the fangs are held parallel to one another, like those of mesothele and mygalomorph spiders, but the chelicerae hang downwards like those of araneomorph spiders. There is no evidence in well-preserved fossils for the opening of a venom gland, thus trigonotarbids were probably not venomous. The chelicerae may have been slightly retractable into the prosoma. Well-preserved palaeocharinids show evidence for a small, slit-like mouth with an upper lip (a labrum or rostrum) and a lower lip (or labium). Inside the mouth there is some sort of filtering system formed from hairs or platelets which strongly suggests that trigonotarbids (like spiders and many other arachnids) could eat only preorally digested, liquified prey. The

pedipalp Pedipalps (commonly shortened to palps or palpi) are the secondary pair of forward appendages among Chelicerata, chelicerates – a group of arthropods including spiders, scorpions, horseshoe crabs, and sea spiders. The pedipalps are lateral to ...

s have the typical arachnid structure with a coxa, trochanter, femur, patella, tibia and tarsus. They are ''pediform'', i.e. they look like small legs and were not highly modified. There is no evidence for a special sperm transfer device as in the modified palpal organ of male spiders. In at least the palaeocharinids and anthracomartids the tip of the pedipalp is modified into a small chela (claw) formed from the tarsal claw (or apotele) and a projection from the tarsus. As mentioned above, a very similar arrangement is seen at the end of the pedipalp in Ricinulei. The walking legs again follow the typical arachnid plan with a coxa, trochanter, femur, patella, tibia, metatarsus and tarsus. The coxae surround a single sternum. In well preserved palaeocharinids there is a ring, or annulus, around the trochanter–femur joint which may be the remains of an earlier leg segment. The legs are largely unmodified, although in Anthracosironidae the forelegs are quite large and spiny, presumably to help catch prey. The legs end in three claws, two large ones and a smaller median claw.

Opisthosoma

The opisthosoma is largely suboval in outline with a flatten dorsal surface. It compose of 12 segments, with some of them had undergone degrees of fusion or reduction, hence the previous misinterpretation of around 8 to 11 segments. Tergite of the first segment partially covered by the posterior margin of preceding carapace, forming a complicated coupling mechanism known as 'locking ridge'. Tergites of segment 2 to 8 (segment 9 in some species) were all laterally divided into 3 (one median and two lateral) plates, with those of segment 2 and 3 fused to each other in most species. However, the corresponding tergites of the family Anthracomartidae are further subdivided into 5 plates. The last 3 segments are usually only visible from the ventral side, with the 2 final segments constricted into a tiny ring-like section known as pygidium. Ventral side of opisthosomal segment 2 to 9 covered by series of lung-bearing opercula (2 and 3) and curved sternites (4 to 9). The first segment apparently lacking any ventral plates. Just like other lung-bearing

s (

scorpion Scorpions are predatory arachnids of the Order (biology), order Scorpiones. They have eight legs and are easily recognized by a pair of Chela (organ), grasping pincers and a narrow, segmented tail, often carried in a characteristic forward cur ...

and tetrapulmonate), the book lungs of trigonotarbids formed by layers of trabecula-bearing lamellae, which is a feature adapted to a terrestrial, air-breathing lifestyle. A pair of ventral sacs located between the posterior operculum and following sternite had been observed in some species.

Paleobiology

In July 2014 scientists used computer-based techniques to re-create a possible walking gait for the animal. A subsequent review article suggested by comparison with mites, with presumably similar lifestyle and environment, a metachronal rather than alternating leg coordination was more likely. Subsequent work by the researchers behind the initial publication used simulation approaches to assess the efficiency of a range of gaits using an updated trigonotarbid model.

Included taxa

As of 2020, 70 valid

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

had been included under Trigonotarbida as follows: ; plesion taxa * '' Palaeotarbus'' Dunlop, 1999 ** '' Palaeotarbus jerami'' (Dunlop, 1996) – Late Silurian, England ; Palaeocharinidae Hirst, 1923 * '' Aculeatarbus'' Shear, Selden & Rolfe, 1987 ** '' Aculeatarbus depressus'' Shear, Selden & Rolfe, 1987 – Mid Devonian, United States * '' Gelasinotarbus'' Shear, Selden & Rolfe, 1987 ** '' Gelasinotarbus bifidus'' Shear, Selden & Rolfe, 1987 – Mid Devonian, United States ** '' Gelasinotarbus bonamoae'' Shear, Selden & Rolfe, 1987 – Mid Devonian, United States ** '' Gelasinotarbus heptops'' Shear, Selden & Rolfe, 1987 – Mid Devonian, United States ** '' Gelasinotarbus reticulatus'' Shear, Selden & Rolfe, 1987 – Mid Devonian, United States * '' Gigantocharinus'' Shear, 2000 ** '' Gigantocharinus szatmaryi'' Shear, 2000 – Late Devonian, United States * '' Gilboarachne'' Shear, Selden & Rolfe, 1987 ** '' Gilboarachne griersoni'' Shear, Selden & Rolfe, 1987 – Mid Devonian, United States * '' Palaeocharinus'' Hirst, 1923 ** '' Palaeocharinus calmani'' Hirst, 1923 – Early Devonian, Scotland ** '' Palaeocharinus hornei'' Hirst, 1923 – Early Devonian, Scotland ** '' Palaeocharinus kidstoni'' Hirst, 1923 – Early Devonian, Scotland ** '' Palaeocharinus rhyniensis'' Hirst, 1923 – Early Devonian, Scotland ** '' Palaeocharinus scourfieldi'' Hirst, 1923 – Early Devonian, Scotland ** '' Palaeocharinus tuberculatus'' Fayers, Dunlop & Trewin, 2005 – Early Devonian, Scotland *'' Spinocharinus'' Poschmann & Dunlop, 2011 **'' Spinocharinus steinmeyeri'' Poschman & Dunlop, 2011 - Devonian, Bürdenbach ; Archaeomartidae Haase, 1890 * '' Archaeomartus'' Størmer, 1970 ** '' Archaeomartus levis'' Størmer, 1970 - Devonian, Alken an der Mosel ; Anthracomartidae Haase, 1890 *synonyms **= Promygalidae Frič, 1904 **= Brachypygidae Pocock, 1911 **= Coryphomartidae Petrunkevitch, 1945 **= Pleomartidae Petrunkevitch, 1945 *'' Anthracomartus'' Karsch, 1882 ** synonyms *** = ''Brachylycosa'' Frič, 1904 *** = ''Cleptomartus'' Petrunkevitch, 1949 *** = ''Coryphomartus'' Petrunkevitch, 1945 *** = ''Cryptomartus'' Petrunkevitch, 1945 *** = ''Oomartus'' Petrunkevitch, 1953 *** = ''Perneria'' Frič, 1904 *** = ''Pleomartus'' Petrunkevitch, 1945 *** = ''Promygale'' Frič, 1901 ** '' Anthracomartus bohemica'' (Frič, 1901) – Late Carboniferous, Czech Republic ** '' Anthracomartus carcinoides'' (Frič, 1901) – Late Carboniferous, Czech Republic *** synonyms **** = ''Promygale rotunda'' Frič, 1901 **** = ''Perneria salticoides'' Frič, 1904 ** '' Anthracomartus elegans'' Frič, 1901 – Late Carboniferous, Czech Republic ** '' Anthracomartus hindi'' Pocock, 1911 – Late Carboniferous, England *** synonyms **** = ''Cleptomartus hangardi'' Guthörl, 1965 **** = ''Cryptomartus meyeri'' Guthörl, 1964 **** = ''Cleptomartus planus'' Petrunkevitch, 1949 **** = ''Cryptomartus rebskei'' Brauckmann, 1984 ** '' Anthracomartus granulatus'' Frič, 1904 – Late Carboniferous, Poland ** '' Anthracomartus janae'' (Opluštil, 1986) – Late Carboniferous, Czech Republic ** '' Anthracomartus kustae'' Petrunkevitch, 1953 – Late Carboniferous, Czech Republic ** '' Anthracomartus minor'' Kušta, 1884 – Late Carboniferous, Czech Republic *** synonym **** = ''Anthracomartus socius'' Kušta, 1888 ** '' Anthracomartus nyranensis'' (Petrunkevitch, 1953) – Late Carboniferous, Czech Republic ** '' Anthracomartus palatinus'' Ammon, 1901 – Late Carboniferous, Germany ** '' Anthracomartus priesti'' Pocock, 1911 – Late Carboniferous, England *** synonyms ****= ''Anthracomartus denuiti'' Pruvost, 1922 ****= ''Cleptomartus plautus'' Petrunkevitch, 1949 ** '' Anthracomartus radvanicensis'' (Opluštil, 1985) – Late Carboniferous, Czech Republic ** '' Anthracomartus triangularis'' Petrunkevitch, 1913 – Late Carboniferous, Canada ** '' Anthracomartus trilobitus'' Scudder, 1884 – Late Carboniferous, United States ** '' Anthracomartus voelkelianus'' Karsch, 1882 – Late Carboniferous, Poland * '' Brachypyge'' Woodward, 1878 ** '' Brachypyge carbonis'' Woodward, 1878 – Late Carboniferous, Belgium * '' Maiocercus'' Pocock, 1911 ** '' Maiocercus celticus'' (Pocock, 1902) – Late Carboniferous, Europe ***synonym ****= ''Maiocercus orbicularis'' Gill, 1911 ; Anthracosironidae Pocock, 1903 * '' Anthracosiro'' Pocock, 1903 ** '' Anthracosiro fritschii'' Pocock, 1903 – Late Carboniferous, Europe ***synonym ****= ''Anthracosiro elongatus'' Waterlot, 1934 ** '' Anthracosiro woodwardi'' Pocock, 1903 – Late Carboniferous, Europe ***synonyms ****= ''Anthracosiro corsini'' Pruvost, 1926 ****= ''Anthracosiro latipes'' Gill, 1909 * '' Arianrhoda'' Dunlop & Selden, 2004 ** '' Arianrhoda bennetti'' Dunlop & Selden, 2004 – Early Devonian, Wales *'' Vratislavia'' Frič, 1904 **'' Vratislavia silesica'' (Roemer, 1878) - Carboniferous, Silesia ; Trigonotarbidae Petrunkevitch, 1949 * '' Trigonotarbus'' Pocock, 1911 ** '' Trigonotarbus arnoldi'' Petrunkevitch, 1955 – Late Carboniferous, France ** '' Trigonotarbus johnsoni'' Pocock, 1911 – Late Carboniferous, England ** '' Trigonotarbus stoermeri'' Schultka, 1991 – Early Devonian, Germany ; Lissomartidae Dunlop, 1995 * '' Lissomartus'' Petrunkevitch, 1949 ** '' Lissomartus carbonarius'' (Petrunkevitch, 1913) – Late Carboniferous, United States ** '' Lissomartus schucherti'' (Petrunkevitch, 1913) – Late Carboniferous, United States ; Aphantomartidae Petrunkevitch, 1945 * synonym **= Trigonomartidae Petrunkevitch, 1949 *'' Alkenia'' Størmer, 1970 **'' Alkenia mirabilis'' Størmer, 1970 - Devonian, Alken an der Mosel *'' Aphantomartus'' Pocock, 1911 ** synonyms ***= Trigonomartus Petrunkevitch, 1913 ***= Phrynomartus Petrunkevitch, 1945a **'' Aphantomartus areolatus'' Pocock, 1911 – Early/Late Carboniferous, Europe ***synonyms ****= ''Aphantomartus pococki'' Pruvost, 1912 ****= ''Trigonomartus dorlodoti'' Pruvost, 1930 ****= ''Eophrynus waechteri'' Guthörl, 1938 ****= ?''Trigonomartus pruvosti'' van der Heide, 1951 ****= ?''Brachylycosa manebachensis'' Müller, 1957 ** '' Aphantomartus ilfeldicus'' (Scharf, 1924) – Permian, Germany ** '' Aphantomartus pustulatus'' (Scudder, 1884) – Late Carboniferous, Europe, North America ***synonyms ****= ?''Kreischeria villeti'' Pruvost, 1912 ****= ''Cleptomartus plötzensis'' Simon, 1971 ; Kreischeriidae Haase, 1890 * '' Anzinia'' Petrunkevitch, 1953 ** '' Anzinia thevenini'' (Pruvost, 1919) – Late Carboniferous, France * '' Gondwanarache'' Pinto & Hünicken, 1980 ** '' Gondwanarache argentinensis'' Pinto & Hünicken, 1980 – Late Carboniferous, Argentina * '' Hemikreischeria'' Frič, 1904 ** '' Hemikreischeria geinitzi'' (Thevenin, 1902) – Late Carboniferous, France * '' Kreischeria'' Geinitz, 1882 ** '' Kreischeria wiedei'' Geinitz, 1882 – Late Carboniferous, Germany * '' Pseudokreischeria'' Petrunkevitch, 1953 ** '' Pseudokreischeria pococki'' (Gill, 1924) – Late Carboniferous, England ***synonym ****= ''Eophrynus varius'' Petrunkevitch, 1949 ; Eophrynidae Karsch, 1882 * synonym **= Hemiphrynidae Frič, 1904 * '' Eophrynus'' Woodward, 1871 ** '' Eophrynus prestvicii'' (Buckland, 1837) – Late Carboniferous, England ** '' Eophrynus udus'' Brauckmann, Koch & Kemper, 1985 – Late Carboniferous, Germany * '' Nyranytarbus'' Harvey & Selden, 1995 ** synonym ***''Hemiphrynus'' Frič, 1901 **'' Nyranytarbus hofmanni'' (Frič, 1901) – Late Carboniferous, Czech Republic ** '' Nyranytarbus longipes'' (Frič, 1901) – Late Carboniferous, Czech Republic * '' Petrovicia'' Frič, 1904 ** '' Petrovicia proditoria'' Frič, 1904 – Late Carboniferous, Czech Republic * '' Planomartus'' Petrunkevitch, 1953 ** '' Planomartus krejcii'' (Kušta, 1883) – Late Carboniferous, Czech Republic ***synonym ****= ''Anthracomartus affinis'' Kušta, 1885 * '' Pleophrynus'' Petrunkevitch, 1945a ** '' Pleophrynus verrucosus'' (Pocock, 1911) – Late Carboniferous, UK, United States ***synonym ****= ''Eophrynus warei'' Dix & Pringle, 1930 ****= ''Pleophrynus ensifer'' Petrunkevitch, 1945a ****= ''Eophrynus jugatus'' Ambrose & Romano, 1972 * '' Pocononia'' Petrunkevitch, 1953 ** '' Pocononia whitei'' (Ewing, 1930) – Early Carboniferous, United States * '' Somaspidion'' Jux, 1982 ** '' Somaspidion hammapheron'' Jux, 1982 * '' Stenotrogulus'' Frič, 1904 ** synonyms ***= ''Cyclotrogulus'' Frič, 1904 ***= ''Pseudoeophrynus'' Příbyl, 1958 **'' Stenotrogulus salmii'' (Stur, 1877) – Late Carboniferous, Czech Republic ***synonyms ****= ''Cyclotrogulus sturii'' Frič, 1904 on Hasse, 1890/small> ****= ''Pseudoeophrynus ostraviensis'' Příbyl, 1958 ;Family uncertain * '' Aenigmatarbus'' Poschmann, Dunlop, Bértoux & Galtier, 2016 **'' Aenigmatarbus rastelli'' Poschmann, Dunlop, Bértoux & Galtier, 2016 - Carboniferous, Graissessac, France *'' Namurotarbus'' Poschmann & Dunlop, 2010 **'' Namurotarbus roessleri'' (Dunlop & Brauckmann, 2006) - Carboniferous, Hagen-Vorhalle ***synonyms ****= ''Archaeomartus roessleri'' Dunlop & Brauckmann, 2006 *'' Permotarbus'' Dunlop & Rößler, 2013 **'' Permotarbus schuberti'' Dunlop & Rößler, 2013 Permian, Chemnitz *'' Tynecotarbus'' Hradská & Dunlop, 2013 **'' Tynecotarbus tichaveki'' Hradská & Dunlop, 2013 - Carboniferous, Týnec ;''

incertae sedis or is a term used for a taxonomy (biology), taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertainty ...

'' * '' Anthracophrynus'' Andrée, 1913 ** '' Anthracophrynus tuberculatus'' Andrée, 1913 – Late Carboniferous, Germany * Areomartus Petrunkevitch, 1913 **'' Areomartus ovatus'' Petrunkevitch, 1913 - Carboniferous, West Virginia *‘''Eophrynus''’ ''scharfi'' Scharf, 1924 – Early Permian, Germany *'' Aphantomartus'' Pocock, 1911 **'' Aphantomartus woodruffi'' (Scudder, 1893) - Carboniferous, Rhode Island ;'' nomina dubia'' * ''Anthracomartus buchi'' (Goldenberg, 1873) – Late Carboniferous, Germany * ''Anthracomartus hageni'' (Goldenberg, 1873) – Late Carboniferous, Germany * ''Elaverimartus pococki'' Petrunkevitch, 1953 – Late Carboniferous, Scotland * ''Eurymartus latus'' Matthew, 1895 – Late Carboniferous, Canada * ''?Eurymartus spinulosus'' Matthew, 1895 – Late Carboniferous, Canada

References

{{Taxonbar, from=Q19107 Arachnid orders Prehistoric arthropod orders Silurian arachnids Devonian arachnids Carboniferous arachnids Permian arachnids Devonian arthropods of North America Carboniferous arthropods of North America Permian arthropods of North America Carboniferous arthropods of Europe Devonian arthropods of Europe Permian arthropods of Europe Silurian arthropods of Europe Silurian first appearances Cisuralian extinctions Taxa named by Alexander Petrunkevitch