''Hughmilleria'' 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 ''Hughmilleria'' have been discovered in deposits of the
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
China
China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...
and 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 ...
. Classified as part of the basal family
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 ...
, the genus contains three species, ''H. shawangunk'' from the eastern
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 ...
, ''H. socialis'' from
Pittsford, New York
Pittsford is a town in Monroe County, New York. A suburb of Rochester, its population was 30,617 at the time of the 2020 census.
The Town of Pittsford (formerly part of the town of Northfield) was settled in 1789 and incorporated in 1796. The ...
, and ''H. wangi'' from
Hunan
Hunan (, ; ) is a landlocked province of the People's Republic of China, part of the South Central China region. Located in the middle reaches of the Yangtze watershed, it borders the province-level divisions of Hubei to the north, Jiangxi to ...
,
China
China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...
. The genus is named in honor of the Scottish
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 ...
Hugh Miller
Hugh Miller (10 October 1802 – 23/24 December 1856) was a self-taught Scottish geologist and writer, folklorist and an evangelical Christian.
Life and work
Miller was born in Cromarty, the first of three children of Harriet Wright (''b ...
.
''H. socialis'' is the type species of
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 ...
, a
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 ...
family classified in the superfamily
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 ...
that is differentiated by their streamlined bodies, the enlargement of their medium-sized
chelicerae
The chelicerae () are the 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 fangs, or similarly ...
and the presence of paired
spines on the walking
appendage
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 ...
s. With the biggest specimen measuring 20 centimetres (8 inches) in length, ''Hughmilleria'' is considered a eurypterid of small size.
Description
![The Eurypterida of New York plate 59](https://upload.wikimedia.org/wikipedia/commons/c/c1/The_Eurypterida_of_New_York_plate_59.jpg)
''Hughmilleria'' is the most basal (primitive) known member of the
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 ...
.
It was a small-sized eurypterid, with the largest specimen measuring 20 cm (8 in), being surpassed by other members of its superfamily, such as ''
Slimonia acuminata
''Slimonia'' is a genus of eurypterid, an extinct group of aquatic arthropods. Fossils of ''Slimonia'' have been discovered in deposits of Silurian age in South America and Europe. Classified as part of the family Slimonidae alongside the relat ...
'', which measured 100 cm (39 in) in length, and ''
Pterygotus grandidentatus'', which could reach 1.75 meters (5 ft 8 in).
The
telson
The telson () is the posterior-most division of the body of an arthropod. Depending on the definition, the telson is either considered to be the final segment of the arthropod body, or an additional division that is not a true segment on accou ...
(the most posterior segment of the body), which was lanceolate and styliform, is distinctly a ''
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 ...
''-like feature. The marginal
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 ...
, the relatively large
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 ...
and the cordate (heart-shaped)
metastoma
The metastoma is a ventral single plate located in the opisthosoma of non-arachnid dekatriatan chelicerates such as eurypterids, chasmataspidids and the genus ''Houia''. The metastoma located between the base of 6th prosomal appendage pair and m ...
(a large plate that is part of the abdomen) show a great resemblance to ''Pterygotus''.
The
carapace
A carapace is a Dorsum (biology), 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 tor ...
was parabolic or subquadrate with oval marginal eyes, the chelicerae were able to extend beyond the carapace margin and the appendages II–V were spiniferous.
The genus is in various ways similar to the more
derived
Derive may refer to:
* Derive (computer algebra system), a commercial system made by Texas Instruments
* ''Dérive'' (magazine), an Austrian science magazine on urbanism
*Dérive, a psychogeographical concept
See also
*
*Derivation (disambiguatio ...
eurypterids of its superfamily, the Pterygotioidea, however, it lacked the expanded and flattened telson that 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 and ''Slimonia'' had. This suggests that ''Hughmilleria'' did not need to use the telson as a rudder to swim.
''Hughmilleria'' is distinguished from other members of
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 ...
by its streamlined body, its subquadrate prosoma (head), its medium-sized chelicerae, its small overall size and the various characteristics it shares with ''Eurypterus''.
History of research
![Hughmilleria shawangunk The Eurypterida of New York](https://upload.wikimedia.org/wikipedia/commons/3/35/Hughmilleria_shawangunk_The_Eurypterida_of_New_York.png)
The genus ''Hughmilleria'' was erected by the American
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 ...
Clifton J. Sarle in 1903 to contain the species ''H. socialis'', which was recovered for the first time in the Pittsford Shale Member of the
Vernon Formation,
New York
New York most commonly refers to:
* New York City, the most populous city in the United States, located in the state of New York
* New York (state), a state in the northeastern United States
New York may also refer to:
Film and television
* '' ...
.
This species is the most abundant species of pterygotioid in the area with around 450 specimens found.
The generic name derives from
Hugh Miller
Hugh Miller (10 October 1802 – 23/24 December 1856) was a self-taught Scottish geologist and writer, folklorist and an evangelical Christian.
Life and work
Miller was born in Cromarty, the first of three children of Harriet Wright (''b ...
, a Scottish geologist and writer who found fossils of eurypterids of the Silurian, among them ''Hughmilleria''.
A variety of ''H. socialis'' was also described, ''Hughmilleria socialis'' var. ''robusta'', but currently it is considered a synonym of the species mentioned.
[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 18.5 http://www.wsc.nmbe.ch/resources/fossils/Fossils18.5.pdf (PDF).]
Four years later, a second species was discovered among the fauna of the Shawangunk grit at
Otisville. It was described as ''Hughmilleria shawangunk'' and was smaller than ''H. socialis''.
The temporal range of ''H. shawangunk'' has been placed between 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 ...
and
Ludlow epoch
In the geological timescale, the Ludlow Epoch (from 427.4 ± 0.5 million years ago to 423.0 ± 2.3 million years ago) occurred during the Silurian Period, after the end of the Homerian Age. It is named for the town of Ludlow in Shropshire, England ...
.
The largest specimens measured 12 cm (5 in) in length,
and differ from the type species by the carapace, which was broader, and the compound eyes which were larger and more prominent than the eyes of ''H. socialis'', among other aspects.
The family
Pterygotidae
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 kno ...
was erected in 1912 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 ...
to constitute a group for the genera ''
Pterygotus
''Pterygotus'' is a genus of giant predatory eurypterid, a group of extinct aquatic arthropods. Fossils of ''Pterygotus'' have been discovered in deposits ranging in age from Middle Silurian to Late Devonian, and have been referred to several di ...
'', ''
Slimonia
''Slimonia'' is a genus of eurypterid, an extinct group of aquatic arthropods. Fossils of ''Slimonia'' have been discovered in deposits of Silurian age in South America and Europe. Classified as part of the family Slimonidae alongside the relat ...
'', ''
Hastimima'' and ''Hughmilleria''. However, Erik N. Kjellesvig-Waering emended the family in 1951, when the genera ''Hastimima'', ''Hughmilleria'', ''Grossopterus'' and ''Slimonia'' were referred to their own family, 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 ...
, which left ''Pterygotus'' as the only genus within the Pterygotidae. In 1961, Erik N. Kjellesvig-Waering split ''Hughmilleria'' into two
subgenera
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'' (''Hughmilleria'') and ''Hughmilleria'' (''Nanahughmilleria''),
although ''
Nanahughmilleria
''Nanahughmilleria'' ("dwarf ''Hughmilleria''") is a genus of eurypterid, an extinct group of aquatic arthropods. Fossils of ''Nanahughmilleria'' have been discovered in deposits of Devonian and Silurian age in the United States, Norway, Russia, ...
'' would be later raised to the genus level.
In 2007, a new species of ''Hughmilleria'' from Hunan, China, was described as ''H. wangi'' based on an almost complete specimen (CNU-E-HLT2006001). The
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 ...
is in honor of Junqing Wang, who found the fossil of the species in 1992. This species was recovered from the
Xiaoxiyu Formation of Hunan, in deposits that suggest that it lived in the
Telychian
In the geologic timescale, the Telychian is the geologic age, age of the Llandovery Epoch of the Silurian geologic period, Period of the Paleozoic geologic era, Era of the Phanerozoic geologic eon, Eon. The Telychian Age was between 438.5 ± 1.2 ...
age of the Silurian, which makes it the oldest eurypterid discovered in China. ''H. wangi'' differs from the North American species by the presence of epimera (lateral "extensions" of the segment) on the entire
postabdomen
Eurypterids, often informally called sea scorpions, are a group of extinct arthropods that form the order Eurypterida. The earliest known eurypterids date to the Darriwilian stage of the Ordovician period 467.3 million years ago. The group is ...
and a slightly wider carapace than in the other species.
Measuring 6 cm (2 in) in length, ''H. wangi'' is the smallest known species of ''Hughmilleria'' and of the Pterygotioidea superfamily.
In addition, if the problematic ''H. lanceolata'', which has been suggested by some researchers to belong to this genus, really did so, it would extend the range of ''Hughmilleria'' to the Silurian of Scotland.
It was originally described as a new species of the new genus ''Himantopterus'' by the English geologist and paleontologist
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 ...
. The body of this species was elongate and attenuated behind. Its telson was lanceolated and its swimming legs were narrow.
This species has also been related to ''Nanahughmilleria'', but recent studies suggest that ''H. lanceolata'' was probably closer to
Eurypteroidea
Eurypteroidea are an extinct superfamily of eurypterids. It contains three families ( Dolichopteridae, Eurypteridae, Strobilopteridae) and two genera of uncertain classification, '' Paraeurypterus'' and '' Pentlandopterus''.
Description
Eurypte ...
. However, the lack of eyes on every specimen of ''H. lanceolata'' hinders the resolution of its phylogenetic position.
Classification
![Hughmilleria shawangunk](https://upload.wikimedia.org/wikipedia/commons/b/b6/Hughmilleria_shawangunk.jpg)
''Hughmilleria'' is classified within the family
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 ...
in the superfamily
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 ...
.
Historically ''Hughmilleria'' was first considered a member of the
Pterygotidae
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 kno ...
until it was assigned to its own family alongside other genera that would later be reclassified.
''Hughmilleria'' and ''Herefordopterus'' shared a subtriangular carapace outline with the pterygotids and the wide telson and genital appendages of all three taxa were similar, although the genital appendages of ''Hughmilleria'' and ''Herefordopterus'' were more similar to those of ''Slimonia'' by the division of these into three segments, in contrast to the undivided morphology in the pterygotids. Still, ''Hughmilleria'' and ''Herefordopterus'' differed from pterygotids and
slimonid
Slimonidae (the name deriving from the type genus '' Slimonia'', which is named in honor of Welsh fossil collector and surgeon Robert Slimon) is a family of eurypterids, an extinct group of aquatic arthropods. Slimonids were members of the super ...
s by the presence of paired spines on the walking appendages, that along with the characteristics that ''Slimonia'' and ''
Ciurcopterus
''Ciurcopterus'' is a genus of eurypterid, an extinct group of aquatic arthropods. Fossils of ''Ciurcopterus'' have been discovered in deposits of Late Silurian age in North America. Classified as part of the family Pterygotidae, the genus conta ...
'' share, suggest that the hughmilleriids were more distant from the pterygotids than ''Slimonia'' was.
Within Hughmilleriidae, both genera possessed a marginal rim much broader anteriorly than posteriorly and appendages spiniferous of ''Hughmilleria''-type, but ''Hughmilleria'' had 18-20 gnathobasic (of the gnathobase, a lower appendage used in the alimentation) teeth on appendage VI, unlike ''Herefordopterus'' and the pterygotids, who had 12-13. Therefore, ''Hughmilleria'' represents the most basal form of Pterygotioidea.
According to Clifton J. Sarle, ''Hughmilleria'' was very similar to ''Eurypterus'', and could be confused with a species of this genus if it was not for the presence of the marginal position of the eyes and the relatively large
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 ...
. However, by its cordate
metastoma
The metastoma is a ventral single plate located in the opisthosoma of non-arachnid dekatriatan chelicerates such as eurypterids, chasmataspidids and the genus ''Houia''. The metastoma located between the base of 6th prosomal appendage pair and m ...
, the intramarginal to marginal position of 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 ...
, the slightly longer preoral appendages, less developed swimming legs and the
opercular appendage, ''Hughmilleria'' was more like ''Pterygotus''.
[Clarke, J. K., Ruedemann R. (1912) " The Eurypterida of New York"]
The cladogram presented below, derived from a 2007 study by researcher O. Erik Tetlie, showcases the interrelationships between the pterygotioid eurypterids.
Paleoecology
![The Eurypterida of New York figure np 1](https://upload.wikimedia.org/wikipedia/commons/2/27/The_Eurypterida_of_New_York_figure_np_1.jpg)
Fossils of ''Hughmilleria'' have been found in
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 ...
deposits from 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 ...
and
Ludlow
Ludlow () is a market town in Shropshire, England. The town is significant in the history of the Welsh Marches and in relation to Wales. It is located south of Shrewsbury and north of Hereford, on the A49 road which bypasses the town. The t ...
epochs
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 ...
.
Together with its close relatives, ''Hughmilleria'' dominated the communities in
brackish
Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuari ...
and
fresh water
Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does include ...
, while ''
Pterygotus
''Pterygotus'' is a genus of giant predatory eurypterid, a group of extinct aquatic arthropods. Fossils of ''Pterygotus'' have been discovered in deposits ranging in age from Middle Silurian to Late Devonian, and have been referred to several di ...
'' 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 ...
'' dominated marine environments.
The Silurian deposits of the Pittsford Shale Member in which fossils of ''H. socialis'' have been found shelter various faunas of eurypterids, including ''
Mixopterus multispinosus'', ''
Erettoperus osiliensis'', ''
Eurypterus pittsfordensis'' and ''
Carcinosoma spiniferus'', among others. Fossils from other organisms were also found, such as the
crustacean
Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group ...
''
Ceratiocaris
''Ceratiocaris'' is a genus of paleozoic phyllocarid crustaceans whose fossils are found in marine strata from the Upper Ordovician until the genus' extinction during the Silurian. They are typified by eight short thoracic segments, seven longe ...
'' and the
ostracod
Ostracods, or ostracodes, are a class of the Crustacea (class Ostracoda), sometimes known as seed shrimp. Some 70,000 species (only 13,000 of which are extant) have been identified, grouped into several orders. They are small crustaceans, typic ...
''
Leperditia''.
Geological features of the formation, such as the friable and
calcareous
Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines.
In zoology
''Calcareous'' is used as an adje ...
mudstone
Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from '' shale'' by its lack of fissility (parallel layering).Blatt, H., and R.J. Tracy, 1996, ''Petrology. ...
, the
argillaceous
Clay minerals are hydrous aluminium phyllosilicates (e.g. kaolin, Al2 Si2 O5( OH)4), sometimes with variable amounts of iron, magnesium, alkali metals, alkaline earths, and other cations found on or near some planetary surfaces.
Clay minerals ...
dolomite Dolomite may refer to:
*Dolomite (mineral), a carbonate mineral
*Dolomite (rock), also known as dolostone, a sedimentary carbonate rock
*Dolomite, Alabama, United States, an unincorporated community
*Dolomite, California, United States, an unincor ...
and the
lithology
The lithology of a rock unit is a description of its physical characteristics visible at outcrop, in hand or core samples, or with low magnification microscopy. Physical characteristics include colour, texture, grain size, and composition. Lit ...
and associated
biota suggests that the environment was marginal marine, very shallow and probably brackish.
See also
*
List of eurypterid genera
*
Timeline of eurypterid research
This timeline of eurypterid research is a chronologically ordered list of important fossil discoveries, controversies of interpretation, and taxonomic revisions of eurypterids, a group of extinct aquatic arthropods closely related to modern arac ...
*
Pterygotidae
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 kno ...
* ''
Herefordopterus
''Herefordopterus'' is a genus of eurypterid, an extinct group of aquatic arthropods. ''Herefordopterus'' is classified as part of the family Hughmilleriidae, a basal family in the highly derived Pterygotioidea superfamily of eurypterids. Fossi ...
''
References
{{Taxonbar, from=Q1910855
Pterygotioidea
Silurian eurypterids
Fossils of the United States
Fossil taxa described in 1903
Eurypterids of North America
Eurypterids of Asia
Bertie Formation