Pseudoniscus

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Pseudoniscus
Temporal range: Silurian
20200921 Pseudoniscus roosevelti.png
Restoration of Pseudoniscus roosevelti
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Chelicerata
Clade: Prosomapoda
Clade: Planaterga
Family: Pseudoniscidae
Genus: Pseudoniscus
Nieszkowski, 1859
Type species
Pseudoniscus aculeatus
Nieszkowski, 1859
Species
  • P. aculeatusNieszkowski, 1859
  • P. clarkeiRuedemann, 1916
  • P. falcatusWoodward, 1868
  • P. rooseveltiClarke, 1902
Synonyms
  • NeolimulusWoodward, 1868

Pseudoniscus is a genus of synziphosurine, a paraphyletic group of fossil chelicerate arthropods. [1] [2] Pseudoniscus was regarded as part of the clade Planaterga. [1] [3] [4] [5] [2] [6] Fossils of the genus have been discovered in deposits of the Silurian period in the United Kingdom (Patrick Burn Formation), the United States and Estonia. Pseudoniscus is one of the two members of the family Pseudoniscidae, the other being Cyamocephalus . [7] [6] [1]

The prosoma of Pseudoniscus covered by a carapace with recurved posterior margin and pointed genal spines. Most of the dorsal feature on the carapace (e.g. ophthalmic ridges, cardiac lobe) are not significantly expressed. [8] At least some species have a median spine in front of the carapace like the close-related Cyamocephalus . [7] Unlike most other synziphosurines with opisthosoma subdivided into a wide preabdomen and narrow postabdomen, the 10-segmented opisthosoma of Pseudoniscus possess undivided, metameric segmentation [8] similar to Pasternakevia . [9] Within Pseudoniscus, P. roosevelti is one of the few synziphosurines that confirmed to have lateral compound eyes, [10] while the remain species lacking unambiguous evidence of it. [8] [10]

Related Research Articles

<span class="mw-page-title-main">Xiphosura</span> Order of marine chelicerates

Xiphosura is an order of arthropods related to arachnids. They are more commonly known as horseshoe crabs. They first appeared in the Hirnantian. Currently, there are only four living species. Xiphosura contains one suborder, Xiphosurida, and several stem-genera.

<span class="mw-page-title-main">Chasmataspidida</span> Order of arthropods

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), with more recent studies suggest that they form a clade (Dekatriata) with Eurypterida and Arachnida. Chasmataspidids are known sporadically in the fossil record through to the mid-Devonian, with possible evidence suggesting that they were also present during the late Cambrian. Chasmataspidids are most easily recognised by having an opisthosoma divided into a wide forepart (preabdomen) and a narrow hind part (postabdomen) each comprising 4 and 9 segments respectively. There is some debate about whether they form a natural group.

<i>Willwerathia</i> Genus of horseshoe crab relatives

Willwerathia is a genus of Devonian arthropod. It is sometimes classified as synziphosurine, a paraphyletic group of horseshoe crab-like fossil chelicerate arthropods, while some studies compare its morphology to an artiopod. Willwerathia known only by one species, Willwerathia laticeps, discovered in deposits of the Devonian period from the Klerf Formation, in the Rhenish Slate Mountains of Germany.

<i>Bembicosoma</i> Extinct genus of chelicerate

Bembicosoma is a genus of synziphosurine, a paraphyletic group of fossil chelicerate arthropods. Bembicosoma was regarded as part of the clade Planaterga. Fossils of the single and type species, B. pomphicus, have been discovered in deposits of the Silurian period in the Pentland Hills, Scotland. Bembicosoma had been tentatively assigned as an eurypterid before its synziphosurine affinities revealed.

Bunaia is a genus of synziphosurine, a paraphyletic group of fossil chelicerate arthropods. Bunaia was tentatively placed as part of the clade Planaterga. The genus contains at least one species: Bunaia woodwardi from the Silurian period in Svalbard, Norway. Only a few morphological information of B. woodwardi had been confirmed, as the species known only from poorly preserved specimens compose of semicircular carapace, fragments of opisthosoma and disarticulated telson. The placement of "Bunaia" heintzi within this genus had been questioned and required further investigation.

<i>Bunodes</i> Genus of horseshoe crab relatives

Bunodes is a genus of synziphosurine, a paraphyletic group of fossil chelicerate arthropods. Bunodes was regarded as part of the clade Planaterga. Fossils of the single and type species, B. lunula, have been discovered in deposits of the Silurian period in Ludlow, England. Bunodes is the type genus of the family Bunodidae, the other genera of the same family being Limuloides.

<i>Cyamocephalus</i> Extinct genus of chelicerate

Cyamocephalus is a genus of synziphosurine, a paraphyletic group of fossil chelicerate arthropods. Cyamocephalus was regarded as part of the clade Planaterga. Fossils of the single and type species, C. loganensis, have been discovered in deposits of the Silurian-aged Patrick Burn Formation in Lesmahagow, Scotland. Cyamocephalus is one of the two members of the family Pseudoniscidae, the other being Pseudoniscus. Cyamocephalus differ from Pseudoniscus by the fused tergites of 6th and 7th opisthosomal segments.

<i>Legrandella</i> Extinct genus of chelicerate

Legrandella is a genus of synziphosurine, a paraphyletic group of fossil chelicerate arthropods. Legrandella was regarded as part of the clade Prosomapoda. Fossils of the single and type species, L. lombardii, have been discovered in deposits of the Devonian period in Cochabamba, Bolivia.

<i>Limuloides</i> Genus of horseshoe crab relatives

Limuloides is a genus of synziphosurine, a paraphyletic group of fossil chelicerate arthropods. Limuloides was regarded as part of the clade Planaterga. Fossils of the genus have been discovered in deposits of the Silurian period in the United Kingdom and potentially in the United States. Limuloides is one of the two genera of the family Bunodidae, the other being the type genus Bunodes. Limuloides is characterized by a carapace with radiated ridges and serrated lateral regions, and an opisthosoma with rows of nodes. Limuloides was once though to have lateral compound eyes on its carapace, but later investigation did not find any evidence of it.

<i>Pasternakevia</i> Extinct genus of chelicerate

Pasternakevia is a genus of synziphosurine, a paraphyletic group of fossil chelicerate arthropods. Pasternakevia was regarded as part of the clade Planaterga. Fossils of the single and type species, P. podolica, have been discovered in deposits of the Silurian period in Podolia, Ukraine.

<i>Weinbergina</i> Extinct genus of chelicerate

Weinbergina is a genus of synziphosurine, a paraphyletic group of fossil chelicerate arthropods. Fossils of the single and type species, W. opitzi, have been discovered in deposits of the Devonian period in the Hunsrück Slate, Germany.

<span class="mw-page-title-main">Synziphosurina</span> Group of arthropods

Synziphosurina is a paraphyletic group of chelicerate arthropods previously thought to be basal horseshoe crabs (Xiphosura). It was later identified as a grade composed of various basal euchelicerates, eventually excluded form the monophyletic Xiphosura sensu stricto and only regarded as horseshoe crabs under a broader sense. Synziphosurines survived at least since early Ordovician to early Carboniferous in ages, with most species are known from the in-between Silurian strata.

<span class="mw-page-title-main">Pseudoniscidae</span> Extinct family of chelicerates

Pseudoniscidae is an extinct family of synziphosurine chelicerates that lived in the Silurian. Pseudoniscidae is classified inside the clade Planaterga, alongside Bunodidae and Dekatriata. Pseudoniscidae is composed by two genera, Cyamocephalus and Pseudoniscus.

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

Borchgrevinkium is an extinct genus of chelicerate arthropod. A fossil of the single and type species, B. taimyrensis, has been discovered in deposits of the Early Devonian period in the Krasnoyarsk Krai, Siberia, Russia. The name of the genus honors Carsten Borchgrevink, an Anglo-Norwegian explorer who participated in many expeditions to Antarctica. Borchgrevinkium represents a poorly known genus whose affinities are uncertain.

<span class="mw-page-title-main">Prosomapoda</span> Clade of arthropods

Prosomapoda is a clade of euchelicerates including the groups Xiphosura and Planaterga, as well as several basal synziphosurid genera. The clade is defined by the lack of exopods of prosomal appendage II-V in the adult instar, where in contrast the exopods of appendage II-V are well-developed in the non-prosomapod euchelicerates Offacolus and Dibasterium.

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

Houia is an extinct genus of dekatriatan, a clade of chelicerate arthropods. Fossils of Houia have been discovered in deposits of the Early Devonian period in Guangxi and Yunnan, both in China. The genus contains two species: H. guangxiensis, from the Pragian to Emsian epoch of Guangxi; and H. yueya, the type species, from the Lochkovian epoch of Yunnan. The name of the genus is derived from the Chinese character (hòu), meaning "horseshoe crab".

<span class="mw-page-title-main">Bunodidae</span> Extinct family of chelicerates

Bunodidae is an extinct family of synziphosurine chelicerates that lived in the Silurian. Bunodidae is classified inside the clade Planaterga alongside Pseudoniscidae and Dekatriata. Bunodidae is composed by two genera, Bunodes and Limuloides.

<i>Venustulus</i> Extinct genus of chelicerate from Wisconsin

Venustulus is a genus of synziphosurine, a paraphyletic group of fossil chelicerate arthropods. Venustulus was regarded as part of the clade Prosomapoda. Fossils of the single and type species, V. waukeshaensis, have been discovered in deposits of the Silurian period in Wisconsin, in the United States. Venustulus is one of the few synziphosurine genera with fossil showing evidence of appendages, the other ones being Weinbergina, Anderella and Camanchia. Despite often being aligned close to horseshoe crabs, it has been found that Venustulus and its relatives form a group made up of various basal euchelicerate arthropods more distant to the xiphosurans.

<i>Camanchia</i> Extinct genus of chelicerate

Camanchia is a genus of synziphosurine, a paraphyletic group of fossil chelicerate arthropods. Camanchia was regarded as part of the clade Prosomapoda. Fossils of the single and type species, C. grovensis, have been discovered in deposits of the Silurian period in Iowa, in the United States. Alongside Venustulus, Camanchia is one of the only Silurian synziphosurine with fossil showing evidence of appendages.

<i>Anderella</i> Extinct genus of chelicerate

Anderella is a genus of synziphosurine, a paraphyletic group of fossil chelicerate arthropods. Anderella was regarded as part of the clade Prosomapoda. Fossils of the single and type species, A. parva, have been discovered in deposits of the Carboniferous period in Montana, in the United States. Anderella is the first and so far the only Carboniferous synziphosurine being described, making it the youngest member of synziphosurines. Anderella is also one of the few synziphosurine genera with fossil showing evidence of appendages, but the details are obscure due to their poor preservation.

References

  1. 1 2 3 Lamsdell, James C. (2013). "Revised systematics of Palaeozoic 'horseshoe crabs' and the myth of monophyletic Xiphosura". Zoological Journal of the Linnean Society. 167 (1): 1–27. doi: 10.1111/j.1096-3642.2012.00874.x . ISSN   0024-4082.
  2. 1 2 Bicknell, Russell D. C.; Pates, Stephen (2020). "Pictorial Atlas of Fossil and Extant Horseshoe Crabs, With Focus on Xiphosurida". Frontiers in Earth Science. 8: 98. Bibcode:2020FrEaS...8...98B. doi: 10.3389/feart.2020.00098 . ISSN   2296-6463.
  3. Selden, Paul A.; Lamsdell, James C.; Qi, Liu (2015). "An unusual euchelicerate linking horseshoe crabs and eurypterids, from the Lower Devonian (Lochkovian) of Yunnan, China". Zoologica Scripta. 44 (6): 645–652. doi: 10.1111/zsc.12124 . ISSN   0300-3256. S2CID   55264483.
  4. Lamsdell, James C.; Briggs, Derek E. G.; Liu, Huaibao P.; Witzke, Brian J.; McKay, Robert M. (2015). "A new Ordovician arthropod from the Winneshiek Lagerstätte of Iowa (USA) reveals the ground plan of eurypterids and chasmataspidids". The Science of Nature. 102 (9–10): 63. Bibcode:2015SciNa.102...63L. doi:10.1007/s00114-015-1312-5. ISSN   0028-1042. PMID   26391849. S2CID   8153035.
  5. Bicknell, Russell D. C.; Lustri, Lorenzo; Brougham, Tom (2019-12-01). "Revision of "Bellinurus" carteri (Chelicerata: Xiphosura) from the Late Devonian of Pennsylvania, USA". Comptes Rendus Palevol. 18 (8): 967–976. Bibcode:2019CRPal..18..967B. doi: 10.1016/j.crpv.2019.08.002 . ISSN   1631-0683.
  6. 1 2 Dunlop, J. A.; Penney, D.; Jekel, D. (2018). "A summary list of fossil spiders and their relatives" (PDF). World Spider Catalog. Natural History Museum Bern. pp. 1–296.
  7. 1 2 Anderson, Lyall I. (1999-01-01). "A new specimen of the Silurian synziphosurine arthropod Cyamocephalus". Proceedings of the Geologists' Association. 110 (3): 211–216. Bibcode:1999PrGA..110..211A. doi:10.1016/S0016-7878(99)80071-6. ISSN   0016-7878.
  8. 1 2 3 Eldredge, Niles; Smith, LeGrande (1974). "Revision of the suborder Synziphosurina (Chelicerata, Merostomata) : with remarks on merostome phylogeny. American Museum novitates ; no. 2543". hdl:2246/2745.{{cite journal}}: Cite journal requires |journal= (help)
  9. "Silurian synziphosurine horseshoe crab Pasternakevia revisited - Acta Palaeontologica Polonica". www.app.pan.pl. Retrieved 2020-10-02.
  10. 1 2 Bicknell, Russell D. C.; Amati, Lisa; Ortega-Hernández, Javier (2019-11-14). "New insights into the evolution of lateral compound eyes in Palaeozoic horseshoe crabs". Zoological Journal of the Linnean Society. 187 (4): 1061–1077. doi:10.1093/zoolinnean/zlz065. ISSN   0024-4082.