''Nanahughmilleria'' ("dwarf ''

Hughmilleria ''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 Hughmille ...

''") is a genus of

eurypterid Eurypterids, often informally called sea scorpions, are a group of extinct arthropods that form the Order (biology), order Eurypterida. The earliest known eurypterids date to the Darriwilian stage of the Ordovician period 467.3 Myr, million yea ...

, an extinct group of aquatic

arthropod Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and Arth ...

s. Fossils of ''Nanahughmilleria'' have been discovered in deposits of

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, whe ...

and

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 beginning of the Devonian Period, Mya. The Silurian is the shortest period of the Paleozo ...

age in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

Norway Norway, officially the Kingdom of Norway, is a Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of the Scandinavian Peninsula. The remote Arctic island of Jan Mayen and t ...

Russia Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the ...

England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...

and

Scotland Scotland (, ) is a country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a border with England to the southeast and is otherwise surrounded by the Atlantic Ocean to the ...

, and have been referred to several different species. ''Nanahughmilleria'' is classified in the family Adelophthalmidae, the only clade in the superfamily

Adelophthalmoidea Adelophthalmidae (the name deriving from the type genus ''Adelophthalmus'', meaning "no obvious eyes") is a family of eurypterids, an extinct group of aquatic arthropods. Adelophthalmidae is the only family classified as part of the superfamily ...

. This clade was characterised by their small size, their parabolic (approximately U-shaped) carapaces and the presence of epimera (lateral "extensions" of the segment) on the seventh segment, among others. ''Nanahughmilleria'' was different from its relatives by the presence of more spines in its

appendages An appendage (or outgrowth) is an external body part, or natural prolongation, that protrudes from an organism's body. In arthropods, an appendage refers to any of the homologous body parts that may extend from a body segment, including anten ...

(limbs) and by its genital

morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines * Morphology (archaeology), study of the shapes or forms of artifacts * Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies ...

. The largest species confidently assigned to the genus was ''N. norvegica'' at 10 cm (3.9 in), making it a comparatively small eurypterid.

Description

Like the other adelophthalmid

s, ''Nanahughmilleria'' was a comparatively small eurypterid. The largest species confidently assigned to the genus, ''N. norvegica'', only reached 10 cm (3.9 in), while the smallest one, ''N. clarkei'', did not exceed 4 cm (1.6 in). Although ''N. lanceolata'' reached 16 cm (6.3 in), this species is probably not an adelophthalmid, but an eurypteroid. Other species such as ''N. notosibirica'' reached 9 cm (3.5 in) in length, while ''N. pygmaea'' had a total length of 8 cm (3.1 in). ''Nanahughmilleria'' had long and narrow reniform (bean-shaped) eyes placed in an intramarginal (occurring within the margin) position. The streamlined form of its body indicates that ''Nanahughmilleria'' was an active swimmer adapted to swim crosscurrent. It had epimera (lateral "extensions" of the segment) present in the seventh segment, separating the preadomen (body segments 1 to 7) from the postabodmen (segments 8 to 12). The genital spatulae, a long, flat piece in the genital aperture, was very short. The walking legs (first to fifth appendages) of ''Nanahughmilleria'' were probably of ''

''-type, that is, with a pair of spines in each

podomere The arthropod leg is a form of jointed appendage of arthropods, usually used for walking. Many of the terms used for arthropod leg segments (called podomeres) are of Latin origin, and may be confused with terms for bones: ''coxa'' (meaning hip, pl ...

(leg segment). The paddle of the swimming leg was relatively wide. As in the other adelophthalmids, the telson was lanceolate and not very expanded. ''Nanahughmilleria'' is only distinguished from the more derived members of Adelophthalmidae in the shorter and smaller spatulae and in the increased spinosity in the appendages.

History of research

First discoveries

The first species of what today is recognized as ''Nanahughmilleria'' was described in 1859 by

John William Salter John William Salter (15 December 1820 – 2 December 1869) was an England, English natural history, naturalist, geologist, and palaeontologist. Salter was apprenticed in 1835 to James De Carle Sowerby, and was engaged in drawing and engraving ...

as "'' Eurypterus pygmaeus''". Although Richard Banks first mentioned this species in 1856, this act is currently considered as ''

nomen nudum In taxonomy, a ''nomen nudum'' ('naked name'; plural ''nomina nuda'') is a designation which looks exactly like a scientific name of an organism, and may have originally been intended to be one, but it has not been published with an adequate descr ...

'' ("naked name", a name coined without an adequate or completely missing description of it). The fossils mentioned by Banks consisted of two specimens, the first of which included carapace with the first five

tergite A ''tergum'' (Latin for "the back"; plural ''terga'', associated adjective tergal) is the dorsal ('upper') portion of an arthropod segment other than the head. The anterior edge is called the 'base' and posterior edge is called the 'apex' or 'mar ...

s (

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 * Dorsal co ...

parts of the body segments) and the 8th and 9th segments of the swimming leg and the second including another nearly complete carapace. Both were collected in Kington,

Herefordshire Herefordshire () is a county in the West Midlands of England, governed by Herefordshire Council. It is bordered by Shropshire to the north, Worcestershire to the east, Gloucestershire to the south-east, and the Welsh counties of Monmouthshire ...

. ''N. pygmaea'' had an elongated carapace rounded along the

anterior Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

margin which narrows gradually anteriorly. A thin rim surrounded the carapace. The eyes were narrow, reniform and intramarginal. Its ocelli (light-sensitive simple eyes) were very small and located centrally. As in most eurypterid groups, the

chelae A chela ()also called a claw, nipper, or pinceris a pincer (biology), pincer-like organ at the end of certain limbs of some arthropods. The name comes from Ancient Greek , through New Latin '. The plural form is chelae. Legs bearing a chela are ...

(pincers) were small. It differs from other species in the more convergent form of the carapace and in the large size of the eyes, which were furthest from the margin. This species reached a length of 8 cm (3.1 in) in total. Erik N. Kjellesvig-Waering classified this species as part of the

subgenus In biology, a subgenus (plural: subgenera) is a taxonomic rank directly below genus. In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between t ...

''Hughmilleria'' (''Nanahughmilleria'') in 1961 along many other species. In 1884, James Hall described another species of ''Eurypterus'', ''E. prominens'', based on a single carapace from the

Clinton Group The Clinton Group (also referred to as the Clinton Formation or the Clinton Shale) is a mapped unit of sedimentary rock found throughout eastern North America. The interval was first defined by the geologist Lardner Vanuxem, who derived the name f ...

, a

geological formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...

of the

. This species differs from the others by the anterior position of its eyes placed in a submarginal (almost in the margin) point, unlike other species of ''Nanahughmilleria'' and '' Parahughmilleria''. In addition, the carapace of this species was long and with ocelli placed forward. It has been suggested that this species could represent a separate genus. In fact, notes left by Kjellesvig-Waering in museum drawers indicate that he wanted to erect a new genus for ''N. prominens'', ''Clintonipterus''. As in ''N. pygmaea'', this species was assigned to ''Nanahughmilleria'' in 1961. In 1911, the

Norwegian Norwegian, Norwayan, or Norsk may refer to: *Something of, from, or related to Norway, a country in northwestern Europe *Norwegians, both a nation and an ethnic group native to Norway *Demographics of Norway *The Norwegian language, including the ...

paleontologist Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of fossi ...

and

geologist A geologist is a scientist who studies the solid, liquid, and gaseous matter that constitutes Earth and other terrestrial planets, as well as the processes that shape them. Geologists usually study geology, earth science, or geophysics, althou ...

Johan Aschehoug Kiær Johan Aschehoug Kiær (October 11, 1869 – October 31, 1931) was a Norwegian paleontologist and geologist. Biography Johan Kiær was born in Drammen, Norway. He was the son of parish priest Hagbarth Kiær (1829–1903) and grandson of shipown ...

described a new species of ''Eurypterus'', ''E. norvegica''. The carapace of this species was parabolic (approximately U-shaped) with small intramarginal arcuate eyes. The metastoma (a large plate that is part of the abdomen) was oval. Its operculum (a plate-like segment which contains the genital aperture) had a long, narrow spatulae (compared to most eurypterids). The telson was lanceolate, with a keel on both dorsal and

ventral Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek language, Greek roots, describe something in its standard anatomical position. Th ...

sides. It had a pair of spines in each podomere of the fifth appendage. The paddle of the swimming leg was relatively wide. It was designated the type species of ''Nanahughmilleria'' by Kjellesvig-Waering in his description of the subgenus. ''N. norvegica'' was the largest species of ''Nanahughmilleria'', measuring 10 cm (3.9 in, with the exception of ''N. lanceolata'', which may represent a separate genus). In 1957, L. P. Pirozhnikov described two new species of eurypterids, ''N. schiraensis'' and ''Parahughmilleria matarakensis'', and erroneously assigned them to the stylonurine genus '' Rhenopterus''. This species is only known by a poorly preserved carapace which was semi-oval and elongated, with a narrow margin surrounding it. The posterior margin was slightly concave. There is only one preserved eye, which was reniform, large and rose slightly from the surface of the carapace. At the closest point between both eyes, the ocelli were placed. The fossils were found at the Matarak Formation in

Minusinsk Minusinsk (russian: Минуси́нск; kjh, Минсуғ) is a historical types of inhabited localities in Russia, town in Krasnoyarsk Krai, Russia. Population: 44,500 (1973). Geography Minusinsk marks the center of the Minusinsk Hollow ...

Siberia Siberia ( ; rus, Сибирь, r=Sibir', p=sʲɪˈbʲirʲ, a=Ru-Сибирь.ogg) is an extensive geographical region, constituting all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has been a part of ...

. Kjellesvig-Waering and Willard P. Leutze noticed that the species did not really represent a ''Rhenopterus'' and they assigned it in 1966 to its current genus. It has been suggested that this species is a synonym of ''P. matarakensis'', but the Russian paleontologist Evgeniy S. Shpinev doesn't agree with this since the prosoma of ''N. schiraensis'' was longer and its eyes were closer to the margin than in ''P. matarakensis''.

Creation of the subgenus and further discoveries

Nanahughmilleria clarkei Eurypterida of New York

In 1961, Kjellesvig-Waering separated ''Hughmilleria'' into two subgenera according to the morphology of the eyes, ''H.'' (''Hughmilleria'') for species with large ovoid marginal eyes and ''H.'' (''Nanahughmilleria'') for species with small reniform intramarginal eyes. For the latter one, ''H.'' (''N.'') ''norvegica'' was designated as subgenotype. He assigned a total of seven species to the subgenus, of which only four (two of them tentatively) are still in ''Nanahughmilleria''. The generic name is composed by the

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

word ''

nana Nana, Nanna, Na Na or NANA may refer to: People and fictional characters * Nana (given name), including a list of people and characters with the given name * Nana (surname), including a list of people and characters with the surname * Nana ( ...

'' ("dwarf") and ''Hughmilleria''. ''N. clarkei'' is based on a series of fossils described and assigned to ''Hughmilleria shawangunk'' by

John Mason Clarke John Mason Clarke (April 15, 1857 – May 29, 1925) was an American teacher, geologist and paleontologist. __TOC__ Early career Born in Canandaigua, New York, the fifth of six children of Noah Turner Clarke and Laura Mason Merrill, he attended ...

and

Rudolf Ruedemann Rudolf Ruedemann (October 16, 1864–June 18, 1956) was a German American paleontologist, widely known as an expert in graptolites, enigmatic fossil animals. He worked at the New York State Museum for over 40 years, including a decade as Stat ...

in 1912. They believed that the carapaces with intramarginal eyes were modified by the compression. While this could happen in a single specimen, it is impossible to be in so many. Kjellesvig-Waering realized this and erected the species ''N. clarkei'' in 1964, named after Clarke, who described the original Shawangunk eurypterid fauna. This small species of only 4 cm (1.6 in) had a lanceolate carapace with intramarginal eyes located anteriorly. The telson was broad and lanceolate. This species is characterized by the presence of spurs in the genal angles (a "flat" part of the carapace edge). It would not be until 2012 when another new species, ''N. notosibirica'', was described by Shpinev. This species is known from two specimens, the

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

(PIN 1139/1) and

paratype In zoology and botany, a paratype is a specimen of an organism that helps define what the scientific name of a species and other taxon actually represents, but it is not the holotype (and in botany is also neither an isotype nor a syntype). Of ...

(PIN 1139/2). Its specific name, ''notosibirica'', comes from the

Greek Greek may refer to: Greece 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 ...

word ''notos'' (southern) and Siberia, referring to the place where it was discovered. The carapace was parabolic and surrounded by a narrow marginal rim and with elongated eyes probably reniform. Only the fourth and fifth pair of prosomal appendages is known. These were of ''Hughmilleria''-type and with rather small spines. The telson was small and wedge-shaped, known from fragmentary remains. The

metasoma The metasoma is the posterior part of the body, or tagma, of arthropods whose body is composed of three parts, the other two being the prosoma and the mesosoma. In insects, it contains most of the digestive tract, respiratory system, and circula ...

(the posterior "part" of the body) was notably narrower than the

mesosoma The mesosoma is the middle part of the body, or tagma, of arthropods whose body is composed of three parts, the other two being the prosoma and the metasoma. It bears the legs, and, in the case of winged insects, the wings. In hymenopterans of t ...

(the "median part"). The total size of the species could be of 9 cm (3.5 in), being one of the largest species of ''Nanahughmilleria''. This species differs from the others in the proportions of the body and position of the eyes. In addition, the species ''N. lanceolata'' is tentatively classified as part of ''Nanahughmilleria''. This species was originally described by Salter in 1856 as another species of his new genus ''Himantopterus''. The swimming legs of this species were long and narrow, reaching the sixth segment of the body. The telson was lanceolate and with a keel in the middle. All known specimens of ''N. lanceolata'' lacks of eyes, making it difficult to determine their phylogenetic position. However, the prosomal and genital appendages were not typical of the Adelophthalmoidea, but probably of the Eurypteroidea.

Classification

''Nanahughmilleria'' is classified as part of the family Adelophthalmidae, the only family within the superfamily

.Dunlop, J. A., Penney, D. & Jekel, D. 2018
A summary list of fossil spiders and their relatives
In World Spider Catalog. Natural History Museum Bern. ''Nanahughmilleria'' was originally considered a subgenus of ''Hughmilleria'', but Kjellesvig-Waering and Leutze considered it sufficiently different from ''Hughmilleria'' and elevated the subgenus to the genus level. It is the only

polyphyletic A polyphyletic group is an assemblage of organisms or other evolving elements that is of mixed evolutionary origin. The term is often applied to groups that share similar features known as homoplasies, which are explained as a result of converg ...

genus (with grouped species that do not share an immediate common ancestor) of Adelophthlmidae, with the species ''N. prominens'' and ''N. lanceolata'' probably representing new and different forms. In 2004, O. Erik Tetlie erected the family Nanahughmilleridae in a thesis to contain the adelophthalmoids with no or reduced genital spatulae and the second to fifth pair of

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 ...

l appendages of ''Hughmilleria''-type. This family contained ''Nanahughmileria'', '' Pittsfordipterus'' and perhaps ''Parahughmilleria''. However, the clade has almost never been used in subsequent studies and lists of eurypterids, and instead, they classify the nanahughmillerids as part of Adelophthalmidae. A basal clade between '' Bassipterus'' and ''Pittsfordipterus'' is better supported than the Nanahughmilleridae, while ''Nanahughmilleria'' is considered the

sister taxon 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 t ...

(closest relative) of the "derived clade" composed by ''Parahughmilleria'' and ''Adelophthalmus''. These eurypterids shared a series of characteristics such as the almost identical carapace, paddle, eye shapes and eye position. However, its short telson, thin cuticular sculpture (ornamentation consisting of small, minute, scales across the back), very small spatulae and increased spinosity in the appendages suggest a more basal position. Before 2004, ''Nanahughmilleria'' was classified in the

Hughmilleriidae Hughmilleriidae (the name deriving from the type genus '' Hughmilleria'', which is named in honor of Scottish geologist Hugh Miller) is a family of eurypterids, an extinct group of aquatic arthropods. The hughmilleriids were the most basal memb ...

family. The cladogram below presents the inferred phylogenetic positions of most of the genera included in the three most derived superfamilies of the

Eurypterina Eurypterina is one of two suborders of eurypterids, an extinct group of chelicerate arthropods commonly known as "sea scorpions". Eurypterine eurypterids are sometimes informally known as "swimming eurypterids". They are known from fossil deposi ...

suborder of eurypterids (Adelophthalmoidea,

Pterygotioidea Pterygotioidea (the name deriving from the type genus ''Pterygotus'', meaning "winged one") is a superfamily of eurypterids, an extinct group of aquatic arthropods. Pterygotioids were the most derived members of the infraorder Diploperculata and ...

and the waeringopteroids), as inferred by O. Erik Tetlie and Markus Poschmann in 2008, based on the results of a 2008 analysis specifically pertaining to the Adelophthalmoidea and a preceding 2004 analysis.

Paleoecology

Fossils of ''Nanahughmilleria'' have been found from the

deposits of the

Llandovery Llandovery (; cy, Llanymddyfri ) is a market town and community in Carmarthenshire, Wales. It lies on the River Tywi and at the junction of the A40 and A483 roads, about north-east of Carmarthen, north of Swansea and west of Brecon. Histo ...

epoch In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured. The moment of epoch is usually decided by ...

to the

deposits of the

Eifelian The Eifelian is the first of two faunal stages in the Middle Devonian Epoch. It lasted from 393.3 ± 1.2 million years ago to 387.7 ± 0.8 million years ago. It was preceded by the Emsian Stage and followed by the Givetian Stage. North American s ...

epoch in

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

and Siberia. It is believed that ''Nanahughmilleria'', along with ''Parahughmilleria'', ''Hughmilleria'' and the

pterygotid Pterygotidae (the name deriving from the type genus ''Pterygotus'', meaning "winged one") is a family of eurypterids, an extinct group of aquatic arthropods. They were members of the superfamily Pterygotioidea. Pterygotids were the largest known ...

s, lived mainly in shallow lakes. In addition, the streamlined shape of the body of ''Nanahughmilleria'' suggests that it was an active swimmer capable of swimming against currents. ''Nanahughmilleria'' can occur in an environment where eurypterids were abundant or scarce. The Silurian deposits of Ringerike,

, where fossils of ''N. norvegica'' have been discovered, include fossil remains of '' Mixopterus kiaeri'', '' Stylonuroides dolichopteroides'', '' Kiaeropterus ruedemanni'' and '' Erettopterus holmi'', among other organisms like the

malacostraca Malacostraca (from New Latin; ) is the largest of the six classes of crustaceans, containing about 40,000 living species, divided among 16 orders. Its members, the malacostracans, display a great diversity of body forms and include crabs, lobst ...

n '' Dictyocaris slimoni'' or the

chasmataspidid Chasmataspidids, sometime referred to as chasmataspids, are a group of extinct chelicerate arthropods that form the order Chasmataspidida. Chasmataspidids are probably related to horseshoe crabs (Xiphosura) and/or sea scorpions (Eurypterida), wit ...

Kiaeria limuloides ''Kiaeria'' is a genus of chasmataspidid, a group of extinct aquatic arthropods. It was originally classified as a xiphosuran of the monotypic family Kiaeriidae. However, in 2019, the British geologist and paleobiologist James C. Lamsdell assi ...

''. On the other hand, ''Nanahughmilleria schiraensis'' and ''Parahughmilleria matakarensis'' are the only animals of the Devonian deposits of

Khakassia Khakassia (russian: Хакасия; kjh, Хакасия, Хакас Чирі, ''Khakasiya'', ''Khakas Çiri''), officially the Republic of Khakassia (russian: Республика Хакасия, r=Respublika Khakasiya, ; kjh, Хакас Рес ...

, Russia, together with land

plant Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclud ...

s. In addition, the English species ''N. pygmaea'' from the Silurian has been associated with '' Salteropterus abbreviatus'', ''Parahughmilleria salteri'', ''Erettopterus spatulatus'' and '' Herefordopterus banksii'', as well as some indeterminate species of cephalaspidomorphs and coelolepids. In the Silurian deposits of the

Shawangunk Formation The Silurian Shawangunk Formation is a mapped bedrock unit in eastern Pennsylvania, New Jersey, and New York (state), New York. It is named for the Shawangunk Ridge for which it is the dominant rock type. The division of the Shawangunk between ...

Pennsylvania Pennsylvania (; ( Pennsylvania Dutch: )), officially the Commonwealth of Pennsylvania, is a state spanning the Mid-Atlantic, Northeastern, Appalachian, and Great Lakes regions of the United States. It borders Delaware to its southeast, ...

, ''N. clarkei'' occur together with ''Parahughmilleria maria'', '' Ruedemannipterus stylonuroides'', '' Hardieopterus myops'' and ''Hughmilleria shawangunk''. Species of the

gnathostomes Gnathostomata (; from Greek: (') "jaw" + (') "mouth") are the jawed vertebrates. Gnathostome diversity comprises roughly 60,000 species, which accounts for 99% of all living vertebrates, including humans. In addition to opposing jaws, living ...

'' Vernonaspis'' and '' Arthrophycus'' have also been found. ''Nanahughmilleria'' fossils have also been found in Scotland.

References

{{Taxonbar, from=Q6962360 Adelophthalmoidea Silurian eurypterids Devonian eurypterids Eurypterids of North America Eurypterids of Europe Eurypterids of Asia Fossil taxa described in 1961