Herefordopterus

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Herefordopterus
Temporal range: Pridoli, 421–419  Ma
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Herefordopterus banksii restoration.png
Restoration of H. banksii
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Chelicerata
Order: Eurypterida
Superfamily: Pterygotioidea
Family: Hughmilleriidae
Genus: Herefordopterus
Tetlie, 2006
Type species
Herefordopterus banksii
Salter, 1856
Synonyms
  • Hughmilleria acuminataSalter, 1859

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. Fossils of the single and type species, H. banksii, have been discovered in deposits of Silurian age in Herefordshire and Shropshire, England. The genus is named after Herefordshire, where most of the Herefordopterus fossils have been found. The specific epithet honors Richard Banks, who found several well-preserved specimens, including the first Herefordopterus fossils.

Contents

Herefordopterus is classified in Hughmilleriidae, a pterygotioid family that is differentiated by their streamlined bodies, the enlargement of its medium-sized chelicerae and the presence of paired spines on the walking appendages. It was distinguished for combining characteristics of Hughmilleria with those of the derived pterygotioids, showing a more advanced morphology than that of Hughmilleria. With the biggest specimen measuring 12 centimetres (5 inches) in length, Herefordopterus is considered a eurypterid of small size.

Description

Size comparison of H. banksii with a human hand Herefordopterus Size.svg
Size comparison of H. banksii with a human hand

Herefordopterus was a small-sized eurypterid with only 12 cm (5 in) in length, being surpassed in size by other pterygotioids such as Slimonia acuminata with 100 cm (39 in) or Jaekelopterus rhenaniae and (potentially) Erettopterus grandis with 2.5 m (8.2 ft). This size makes it the smallest genus and one of the smallest species of the entire Pterygotioidea superfamily, the related Hughmilleria wangi at 6 cm (3 in) being the smallest one. [1]

It had a parabolic (approximately U-shaped) to campanulate (bell-shaped) carapace (head plate) with an angular anterior margin that narrows toward the eyes, the second to fifth pair of prosomal appendages with a single pair of short spines on each podomere (leg segments) and large oval and marginal eyes. The ocelli (light-sensitive simple eyes) were relatively large and placed between the posterior part of the eyes. The postabdominal segments (segments 8 to 12) were longer than the preabdominal segments (segments 1 to 7) and lacking of ornamentation. It had 12-13 gnathobasic (of the gnathobase, a lower appendage used in feeding) teeth in the sixth appendage, as in pterygotids. The genital operculum (a plate-like segment which contains the genital aperture) of Herefordopterus was composed by two fused opercular segments posterior to the deltoid plates (two small plates above the genital appendage), which are more clearly expressed in the type B specimens (assumed to be males). It was ornamented with prominent scales. The telson (the most posterior segment of the body) was wide anteriorly posteriorly tapering to a lanceolate shape with a keel. It presents a marginal ornamentation of crenulated (slightly notched) margins composed of dark scales. [2]

Herefordopterus stands out for its great resemblance to Hughmilleria with derived (more "advanced") elements reminiscent of Slimonidae and Pterygotidae, such as its number of gnathobasic teeth or the ornamentation of the telson. [2]

History of research

Herefordshire UK relief location map.jpg
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Perton
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Kington
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Ludlow
Ubication of the three locations where fossils of Herefordopterus have been found. Type locality in italics.

Herefordopterus banksii was first considered a species of Himantopterus (a preoccupied name, now Erettopterus), H. banksii, by John William Salter in 1856, making it one of the oldest eurypterid species. The first fossils, discovered in Kington, include the prosoma (head) and fragmentary remains of the nine first segments. Salter noted a scale-like sculpturing on its forward margin and related the species to H. lanceolatus (now tentatively placed in the genus Nanahughmilleria ). He decided to dedicate the specific name banksii to Richard Banks of Kington, who found several well-preserved specimens of Himantopterus and sent them to Salter. [3] Three years later, Salter erroneously assigned H. banksii to Pterygotus (Erettopterus) based on bilobed telsons of Erettopterus spatulatus that he misidentified as belonging to H. banksii. In turn, the telsons of H. banksii were referred to Stylonurus megalops (now in the genus Hardieopterus ). [2] It would not be until 1934 when Størmer classified P. (E.) banksii in Hughmilleria. H. banksii was described in more detail in 1951 by Kjellesvig-Waering, who agreed that specimens assigned to S. megalops should be assigned to H. banksii. However, he was also wrong in assigning a walking leg of Salteropterus abbreviatus to the hughmilleriid species. [4] Currently, all descriptions prior to 2006 of H. banksii are considered inadequate or of little use. [2]

The separation of H. banksii as an independent genus was predicted by Størmer in 1973, when he noticed that the morphology of the type B genital appendage was more similar to that of Parahughmilleria . [5] In 2006, O. Erik Tetlie redescribed the species based on the majority of available material. The new study helped to redistribute erroneously assigned material, to reinterpret the morphology of H. banksii and to question the basality and phylogenetic position of Hughmilleria with respect to Slimonidae and Pterygotidae. Tetlie erected a new genus due to the obvious similarity with Hughmilleria with several derived characteristics shared with the slimonids and pterygotids. The name Herefordopterus derives from Herefordshire, where the vast majority of its fossils have been found. In addition, the poorly known species Hughmilleria acuminata, previously known only by two telsons, was synonymized with Herefordopterus due to being anteriorly wide. However, these telsons had a wider portion than usual than in the rest of the telsons of H. banksii, in addition to being completely flattened, although this may be due to the different degree of compression and preservation. [2]

Classification

Herefordopterus is classified within the family Hughmilleriidae in the superfamily Pterygotioidea. [6] Originally, Herefordopterus was considered a species of Himantopterus, [3] later it would be classified under Hughmilleria until it was reclassified in its own genus in 2006 by O. Erik Tetlie. [2]

Herefordopterus and Hughmilleria 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 Herefordopterus and Hughmilleria 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, Herefordopterus and Hughmilleria differ from pterygotids and slimonids by the presence of paired spines on the walking appendages, that along with the characteristics that Slimonia and Ciurcopterus share, suggest that the hughmilleriids are more distant from the pterygotids than Slimonia is. [7] Within Hughmilleriidae, both genera possessed a marginal rim much broader anteriorly than posteriorly and spiniferous appendages, but Hughmilleria had 18-20 gnathobasic teeth on appendage VI, unlike Herefordopterus and the pterygotids, which had 12-13. Therefore, Herefordopterus is placed as the sister taxon (closest relative) of the clade of Slimonidae and Pterygotidae and a more derived form than Hughmilleria. [2]

The cladogram presented below, derived from a 2007 study by researcher O. Erik Tetlie, showcases the interrelationships between the pterygotioid eurypterids. [8]

Pterygotioidea

Paleoecology

The Late Silurian of Herefordshire was home to a wide array of different eurypterids, including species of Erettopterus , Eurypterus , Nanahughmilleria , Marsupipterus , Salteropterus and potentially Slimonia (depending on the identity of S. stylops). This eurypterid fauna coexisted with lingulids, ostracods and cephalaspidimorph fish, such as Hemicyclaspis and Thelodus . [9] Herefordopterus lived in a benthic (at the lowest level of water) environment near an intertidal sandy shore and intertidal sandy mudflat environments. [10] The lithology of the site was of green mudstone and sandstone, with mud cracks and pedogenic carbonate (calcrete). [9]

See also

Related Research Articles

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<i>Pterygotus</i> Extinct genus of eurypterid

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<i>Slimonia</i> Extinct genus of arthropods

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 related Salteropterus, the genus contains three valid species, S. acuminata from Lesmahagow, Scotland, S. boliviana from Cochabamba, Bolivia and S. dubia from the Pentland Hills of Scotland and one dubious species, S. stylops, from Herefordshire, England. The generic name is derived from and honors Robert Slimon, a fossil collector and surgeon from Lesmahagow.

<i>Hughmilleria</i> Genus of extinct arthropods

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 Hughmilleriidae, the genus contains three species, H. shawangunk from the eastern United States, H. socialis from Pittsford, New York, and H. wangi from Hunan, China. The genus is named in honor of the Scottish geologist Hugh Miller.

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<i>Bassipterus</i> Extinct genus of arthropods

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<i>Nanahughmilleria</i> Extinct genus of arthropods

Nanahughmilleria 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, England and Scotland, and have been referred to several different species.

Salteropterus is a genus of eurypterid, an extinct group of aquatic arthropods. Fossils of Salteropterus have been discovered in deposits of Late Silurian age in Britain. Classified as part of the family Slimonidae, the genus contains one known valid species, S. abbreviatus, which is known from fossils discovered in Herefordshire, England, and a dubious species, S. longilabium, with fossils discovered in Leintwardine, also in Herefordshire. The generic name honours John William Salter, who originally described S. abbreviatus as a species of Eurypterus in 1859.

<i>Erettopterus</i> Extinct genus of arthropods

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<i>Parahughmilleria</i> Extinct genus of arthropods

Parahughmilleria is a genus of eurypterid, an extinct group of aquatic arthropods. Fossils of Parahughmilleria have been discovered in deposits of the Devonian and Silurian age in the United States, Canada, Russia, Germany, Luxembourg and Great Britain, and have been referred to several different species. The first fossils of Parahughmilleria, discovered in the Shawangunk Mountains in 1907, were initially assigned to Eurypterus. It would not be until 54 years later when Parahughmilleria would be described.

<span class="mw-page-title-main">Pterygotidae</span> Extinct family of eurypterids

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<span class="mw-page-title-main">Pterygotioidea</span> Extinct superfamily of eurypterids

Pterygotioidea is a superfamily of eurypterids, an extinct group of aquatic arthropods. Pterygotioids were the most derived members of the infraorder Diploperculata and the sister group of the adelophthalmoid eurypterids. The group includes the basal and small hughmilleriids, the larger and specialized slimonids and the famous pterygotids which were equipped with robust and powerful cheliceral claws.

<span class="mw-page-title-main">Stylonuroidea</span> Extinct superfamily of arthropods

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<span class="mw-page-title-main">Adelophthalmidae</span> Family of eurypterids

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<span class="mw-page-title-main">Hughmilleriidae</span> Extinct family of eurypterids

Hughmilleriidae is a family of eurypterids, an extinct group of aquatic arthropods. The hughmilleriids were the most basal members of the superfamily Pterygotioidea, in contrast with the more derived families Pterygotidae and Slimonidae. Despite their classification as pterygotioids, the hughmilleriids possessed several characteristics shared with other eurypterid groups, such as the lanceolate telson.

<span class="mw-page-title-main">Slimonidae</span> Extinct family of eurypterids

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<i>Eysyslopterus</i> Extinct genus of arthropods

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<i>Necrogammarus</i> Extinct genus of arthropods

Necrogammarus salweyi is the binomial name applied to an arthropod fossil discovered in Herefordshire, England. The fossil represents a fragmentary section of the underside and an appendage of a pterygotid eurypterid, a group of large and predatory aquatic arthropods that lived from the late Silurian to the late Devonian. The Necrogammarus fossil is Late Silurian in age and its generic name means "dead lobster", deriving from Ancient Greek νεκρός and Latin gammarus ("lobster").

<i>Ciurcopterus</i> Extinct genus of arthropods

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 contains two species, C. sarlei from Pittsford, New York and C. ventricosus from Kokomo, Indiana. The genus is named in honor of Samuel J. Ciurca, Jr., who has contributed significantly to eurypterid research by discovering a large amount of eurypterid specimens, including the four specimens used to describe Ciurcopterus itself.

<span class="mw-page-title-main">Timeline of eurypterid research</span>

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 arachnids and horseshoe crabs that lived during the Paleozoic Era.

References

  1. Lamsdell, James C.; Braddy, Simon J. (2009). "Cope's rule and Romer's theory: patterns of diversity and gigantism in eurypterids and Palaeozoic vertebrates". Biology Letters . 6 (2): 265–269. doi:10.1098/rsbl.2009.0700. ISSN   1744-9561. PMC   2865068 . PMID   19828493. Supplemental material.
  2. 1 2 3 4 5 6 7 Tetlie, O. Erik (2006). "Eurypterida (Chelicerata) from the Welsh Borderlands, England". Geological Magazine. 143 (5): 723–735. Bibcode:2006GeoM..143..723T. doi:10.1017/S0016756806002536. ISSN   1469-5081. S2CID   83835591.
  3. 1 2 "The Quarterly Journal of the Geological Society of London". Geological Society of London . 1856.
  4. Kjellesvig-Waering, Erik N. (1951). "Downtonian (Silurian) Eurypterida from Perton, near Stoke Edith, Herefordshire". Geological Magazine. 88 (1): 1–24. Bibcode:1951GeoM...88....1K. doi:10.1017/S0016756800068874. ISSN   1469-5081. S2CID   129056637.
  5. Størmer, Leif (1973). "Arthropods from the Lower Devonian (Lower Emsian) of Alken an der Mosel, Germany. Part 3: Eurypterida, Hughmilleriidae". Senckenbergiana Lethaea. 54: 119–205.
  6. 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).
  7. Tetlie, O. Erik; Briggs, Derek E. G. (2009-09-01). "The origin of pterygotid eurypterids (Chelicerata: Eurypterida)". Palaeontology. 52 (5): 1141–1148. Bibcode:2009Palgy..52.1141T. doi: 10.1111/j.1475-4983.2009.00907.x . ISSN   1475-4983.
  8. O. Erik Tetlie (2007). "Distribution and dispersal history of Eurypterida (Chelicerata)" (PDF). Palaeogeography, Palaeoclimatology, Palaeoecology . 252 (3–4): 557–574. Bibcode:2007PPP...252..557T. doi:10.1016/j.palaeo.2007.05.011. Archived from the original (PDF) on 2011-07-18.
  9. 1 2 "Fossilworks - Eurypterid-Associated Biota of the Temeside Shale, Ludlow and Perton, England (Silurian of the United Kingdom)". fossilworks.org. Archived from the original on March 21, 2018.
  10. Burkert, C. (2018). "Environment preference of eurypterids–indications for freshwater adaptation?".{{cite journal}}: Cite journal requires |journal= (help)