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Chasmataspidida ( allemand )

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Chasmataspidida ist eine ausgestorbene Ordnung innerhalb der Kieferklauenträger (Chelicerata).

Merkmale

Chasmataspidida sind echte Kieferklauenträger mit einem kurzen, breiten Sklerit (1. opisthosomales Segment), gefolgt von einem dreisegmentierten Preabdomen (Segmente 2–4) und einem neunsegmentierten Postabdomen (Segmente 5–13).

Fundorte

Arten der Ordnung Chasmataspidida wurden in Nordamerika (Tennessee), Europa (Deutschland und Schottland) und Russland gefunden.

Systematik

Einige Autoren ordnen die Chasmataspidida nicht einer Klasse zu, da die Monophylie der Merostomata fragwürdig und die basalen Beziehungen innerhalb der Euchelicerata kontrovers sind. Chasmataspidida teilen viele Gemeinsamkeiten mit Xiphosura (Schwertschwänze) und Eurypterida (Seeskorpione) und werden daher von Anderson & Seldon 1997 von den Xiphosura getrennt[1]. Die von Starabogatov[2] aufgestellte Überordnung Chasmataspidiformii entspricht der Ordnung Chasmataspidida und die Ordnung Chasmataspidiformes der Familie Chasmataspididae, ebenso wie die von Bergström[3] aufgestellte Überfamilie Chasmataspidacea. Ein jüngeres Synonym der Ordnung ist Diploaspidida Simonetta & Delle Cave, 1978.

Man unterscheidet zurzeit zwei Familien mit sieben Arten in sechs Gattungen:

Ungeklärt ist noch, ob es sich bei dem aus Sibirien stammenden Eurypterus stoermeri Novojilov, 1959 möglicherweise doch um ein Vertreter von Chasmataspidida handelt.[4]

Quellen

Literatur

  • Jason A. Dunlop, Lyall I. Anderson, Simon J. Braddy: A redescription of Chasmataspis laurencii Caster & Brooks, 1956 (Chelicerata: Chasmataspidida) from the Middle Ordovician of Tennessee, USA, with remarks on chasmataspid phylogeny. Transactions of the Royal Society of Edinburgh: Earth Sciences 94, 2004: 207–225. PDF

Einzelnachweise

  1. L. I. Anderson, P. A. Selden: Opisthosomal fusion and phylogeny of Palaeozoic Xiphosura. Lethaia 30, 1997: 19–31.
  2. Y. I. Starobogatov: The systematics and phylogeny of the lower chelicerates (a morphological analysis of the Paleozoic groups). Paleontologicheskii Zhurnal 1, 1990: 4–17.
  3. J. Bergström: Functional morphology and evolution of xiphosurids. Fossils and Strata 4, 1975: 291–305.
  4. O. E. Tetlie, S. J. Braddy: The first Silurian chasmataspid, Loganamaraspis dunlopi gen. et sp. nov. (Chelicerata: Chasmataspidida) from Lesmahagow, Scotland, and its implications for eurypterid phylogeny. Transactions of the Royal Society of Edinburgh: Earth Sciences 94, 2004: 227–234.
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Chasmataspidida: Brief Summary ( allemand )

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Chasmataspidida ist eine ausgestorbene Ordnung innerhalb der Kieferklauenträger (Chelicerata).

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Chasmataspidida ( anglais )

fourni par wikipedia EN

Chasmataspidids, sometime referred to as chasmataspids,[1][2][3] 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),[4][1] with more recent studies suggest that they form a clade (Dekatriata) with Eurypterida and Arachnida.[5][6][7][8] Chasmataspidids are known sporadically in the fossil record through to the mid-Devonian,[9] with possible evidence suggesting that they were also present during the late Cambrian.[1] Chasmataspidids are most easily recognised by having an opisthosoma divided into a wide forepart (preabdomen) and a narrow hindpart (postabdomen) each comprising 4 and 9 segments respectively.[1][10] There is some debate about whether they form a natural (i.e. monophyletic) group.[3][1][4]

Distribution

Geographic distribution of chasmataspidids.

Chasmataspidids survived at least since Ordovician to mid-Devonian in age. As of 2019, most chasmataspidids (with a total of 9 species) are known from the Devonian strata, while the preceding Silurian and Ordovician period each have 3 and 2 species being described.[11][12] Diploaspis is the only genus of chasmataspidids that unambiguously comprises species from different periods (D. casteri and D. muelleri from Devonian and D. praecursor from silurian).[13] There was also trace fossil compose of resting imprints with Chasmataspis-like outline discovered from late-Cambrian stratum, which might suggest an earlier occurrence of chasmataspidids.[1]

Morphology

Most chasmataspidids are small arthropods with a body length that did not exceed 3 centimeters, with the ordovician species being exceptionally large, ranging between 10 (Chasmataspis) and 29 centimeters (Hoplitaspis).[11]

The streamlined body of chasmataspidid compose of a rigid prosoma and an externally 13-segmented opisthosoma. Like eurypterid, dorsal side of the prosoma was covered by a rigid carapace (prosomal dorsal shield) that bore a pair of larger lateral (presumably compound[10]) eyes and a pair of tiny median ocelli.[10] Chasmataspidid readily distinguish from other chelicerates by the subdivision of the 13 opisthosomal segments into a widen, 4-segmented preabdomen and a slender, 9-segmented postabdomen.[14][10] the tergite (dorsal exoskeleton) of the first opisthosomal/preabdomimal segment retain as a narrow element known as 'microtergite',[14] which is not observable in eurypterid.[10] The posterior three preabdominal segments are well developed, forming a rigid box-like section called 'buckler'.[10] The postabdominal segments are cylindrical and the last segment terminated with a spine/plate-like telson, which is usually relatively short.[10]

Appendages

Since the appendages of chasmataspidid are rarely preserved in the fossil, most species have only fragile or even no appendicular structures had been described. Based on available materials, the prosoma compose of 6 appendage pairs (appendage I - VI) just like most euchelicerates, which were 1 pair of small chelicerae and 5 pairs of limb-like appendages, although the detail morphology of the former is still unclear.[10][11] The coxae (basalmost limb segments) of appendage II-VI bore gnathobases.[15][11] At least the posteriormost appendage pair (appendage VI) of prosoma seems to be differ between families.[11] Appendage of Chasmataspididae known only from 2 disarticulated specimens of appendages which interpreted as appendage VI of Chasmataspis.[11] the appendage bore exopod-like structure on the base and terminated with a chelate (pincer), similar to those of a xiphosuran.[1] On the other hand, Appendage VI modified into a paddle that strikingly resemble to those of an eurypterine (swimming eurypterid) was discovered in some species of Diploaspididae,[14][11] but the basal diploaspidid Loganamaraspis possibly did not possess this character on Appendage VI.[3] the limb-like appendage II-V of diploaspidids are either featureless[14] or bore rows of spines.[13][11]

Opisthosomal appendages are even rarely being observed and only known from a few diploaspidid materials.[15][3][11] they are at least present on the ventral side of preabdomen, each pair originated from one preabdominal segment.[10] the anteriormost appendicular structure of opisthosoma was metastoma, a plate-like structure interpreted as a fused appendage pair of first opisthosomal segment,[10] situated between the gnathobase of prosomal appendage VI.[11] Beyond the metastoma were 3 pairs of plate-like opercula originated from the 3 buckler segments, with the first operculum pair (genital operculum) bore a medially positioned genital appendage that extend until the posterior region of second operculum pair.[15][11] Some of the opercula may have book gills just like those of xiphosurans and eurypterids, but the evidence are equivocal.[16] Previous reports of a large operculum cover the whole ventral surface of buckler are most likely an misinterpretation of the ventral buckler wall (sternites or dorsal surface of gill chamber), which were originally enclosed by the opercula in life.[17][16] The metastoma, opercula and genital appendage are shared characters between chasmataspidid and eurypterid, but unlike the fused first and second operculum pair of eurypterid, the two operculum pairs seems to be unfused in chasmataspidid.[10] Possible chasmataspidid trace fossil from cambrian have imprints resembling 6 pairs of opercula.[1] If the interpretation is true, chasmataspidid may had extra 3 pairs of opercula on the first 3 postabdominal segment as well.[10]

Representative genera

Chasmataspis

Reconstruction of Chasmataspis laurencii.

The first chasmataspidid to be discovered was Chasmataspis laurencii, described by the American palaeontologists Kenneth E. Caster and H. K. Brooks in 1956.[18] These Ordovician fossils come from the site of the Douglas Dam in Tennessee, USA. They are the most xiphosuran-like of the known chasmataspidid species, with a horseshoe-shaped carapace. Caster & Brooks raised a new family, Chasmataspididae, to accommodate these specimens. The species was redescribed by Jason Dunlop and colleagues in 2004.[1]

Diploaspis

Reconstruction of Diploaspis casteri.

The next species to be discovered were Diploaspis casteri and Heteroaspis novojilovi; both described by the Norwegian palaeontologist Leif Størmer from the early Devonian of Alken an der Mosel in Germany in 1972.[19]

A revision by Markus Poschmann and co-workers in 2005 recognised H. novojilovi as a synonym of D. casteri. The two species appear to actually be preservational variants of the same species. Poschmann et al. also described a second species as Diploaspis muelleri.[16]

A third species, Diploaspis praecursor (Late Silurian, Bertie Group, New York State), was described by Lamsdell and Briggs in 2017.[13]

Forfarella

Reconstruction of Forfarella mitchelli.

Forfarella mitchelli from the early Devonian of the Forfar region in the Midland Valley of Scotland was described by Jason Dunlop and colleagues in 1999; although the fossil had actually been recognised as a chasmataspidid and provisionally labelled as such some years previously by Charles Waterston. Forfarella mitchelli is not very well preserved, but does show the characteristic chasmataspidid body plan.[2]

Achanarraspis

The stratigraphically youngest chasmataspidid is Achanarraspis reedi, described by Lyall Anderson and colleagues in 2000, from the mid-Devonian Achanarras quarry in Caithness, Scotland, a site rich in fish fossils.[17]

Octoberaspis

Reconstruction of Octoberaspis ushakovi

Well preserved chasmataspidids were recovered from the early Devonian of October Revolution Island, part of the Severnaya Zemlya group in the Russian Arctic. Originally briefly described as eurypterids, they were formally described as Octoberaspis ushakovi by Jason Dunlop in 2002. Octoberaspis is one of the few chasmataspidids with well-documented opisthosomal appendages, reveal some characters previously though to be eurypterid-exclusive were also shared by chasmataspidid as well.[15]

Loganamaraspis

Loganamaraspis dunlopi discovered from a famous Silurian fossil locality near Lesmahagow in Scotland. Described by Erik Tetlie and Simon Braddy in 2003, it was placed in Diploaspididae, but interpreted as being somewhat more intermediate in form between the Chasmataspis and Diploaspidid body plans.[3]

Dvulikiaspis

Reconstruction of Dvulikiaspis menneri

Fossils of Dvulikiaspis menneri discovered from the Imangda River of Taymyr Peninsula were originally interpreted as a species of eurypterid genus Stylonurus, and formally described as a new genus of chasmataspidid by David J. Marshall and co-authors in 2014. Dvulikiaspis menneri is one of the few well-preserved chasmataspidid, with distal morphology of appendage II-VI had been revealed.[14]

Hoplitaspis

Reconstruction of Hoplitaspis hiawathai

Hoplitaspis hiawathai is the second known species of Ordovician chasmataspidid, discovered from the Big Hill Lagerstätte of Michigan in United States, described by James C. Lamsdell and co-authors in 2019. With nearly complete set of appendages being observable, Hoplitaspis hiawathai is the most complete chasmataspidid known at that time. Each of the paddle of Hoplitaspis hiawathai has a claw instead of an intersegmental element like those of other diploaspidids, providing clues on the relationship between the appendage VI of Chasmataspis and diploaspidids.[11]

Classification

Phylogenetic position

Chelicerata

Pycnogonida Nymphon signatum 194389384 (white background).jpg

Euchelicerata

Xiphosura Limulus polyphemus (aquarium) (white background).jpg

Dekatriata

Chasmataspidida 20200606 Chasmataspis laurencii.png

Sclerophorata

Eurypterida Eurypterus Paleoart (no background).png

Arachnida Aptostichus simus Monterey County.jpg

Summarized phylogenetic position of Chasmataspidida as of 2010s.[5][6][7][8]

Chasmataspidids have a controversial phylogenetic position within Chelicerata. The first species to be discovered were thought to be unusual fossil xiphosuran,[5] while later species were often based on specimens initially misidentified as eurypterids.[14] Chasmataspidids had been interpreted as relatives/members of either xiphosurans or eurypterids,[20][4] or forming a clade (Dekatriata) with eurypterids and arachnids.[5][6][7][8] Some studies even suggest that chasmataspidids may not represent a monophyletic taxon - for example as a paraphyletic grade where the eurypterids arose;[3][4] or a polyphyletic group with Chasmataspis and diploaspidids more closely related to xiphosuans and eurypterids, respectively.[1] The polyphyletic hypothesis was based on the xiphosuran-like characters of Chasmataspis (e.g. genal spines, chelate limbs, fused opisthosomal segments) and eurypterid-like characters found on diploaspidid genera (e.g. paddles on appendage VI).[1] However this interpretation could be unreliable, as the characters are either partially shared by both xiphosuans and eurypterids[1] (e.g. genal spines were be found in eurypterid juveniles;[21] some xiphosurans have non-chelate limbs and unfused opisthosoma[22]) or more likely represent a result of parallel evolution (e.g. the paddles of diploaspidids and swimming eurypterids have different component[11]). Additionally, the monophyly of chasmataspidids could be supported by the unique component of 4-segmented preabdomen and 9-segmented postabdomen as well.[1][10] As of 2010s, many studies supports the monophyly of Chasmataspidida and Dekatriata (Chasmataspidida+Eurypterida+Arachnida).[5][23][6][7][8][24][25][11]

Interrelationships

Chasmataspidida Chasmataspididae

Chasmataspis laurencii 20200606 Chasmataspis laurencii.png

Diploaspididae

Loganamaraspis dunlopi

Dvulikiaspis menneri 20200610 Dvulikiaspis menneri.png

Achanarraspis reedi

Heteroaspis stoermeri

Octoberaspis ushakovi 20200605 Octoberaspis ushakovi.png

Diploaspis praecursor 20200607 Diploaspis praecursor.png

Diploaspis casteri 20200731 Diploaspis casteri.png

Diploaspis muelleri

Internal phylogeny of Chasmataspidida based on Selden, Lamsdell & Liu (2015),[6] with addition of Diploaspis praecursor based on Lamsdell & Briggs (2017).[13]

As of 2019, up to 12 genera had been associated within Chasmataspidida. With the exception of Diploaspis which compose of 3 species since 2017,[13] all chasmataspidid genera are monotypic.[9] The order Chasmataspidida subdivided into two families: Chasmataspididae and Diploaspididae. the former consists of Chasmataspis (and possibly also Kiaeria[12]) while the latter include the remaining genera.[9] Chasmataspididae is defined by a horseshoe-shaped carapace with distinct genal spines and a completely fused preabdomen;[1] while Diploaspididae is defined by a semicircular to subquadrate carapace and a preabdomen with curved, nontrilobate segments.[14]
Chasmataspidida Caster & Brooks, 1956

  • Kiaeria Størmer, 1934 (might belong to Chasmataspididae[12])
    • Kiaeria limuloides Størmer, 1934Silurian
  • Chasmataspididae Caster & Brooks, 1956
  • Diploaspididae Størmer, 1972[19]
    • Achanarraspis Anderson, Dunlop & Trewin, 2000
      • Achanarraspis reedi Anderson, Dunlop & Trewin, 2000Devonian[17]
    • Diploaspis Størmer, 1972
      • Diploaspis casteri Størmer, 1972—Devonian[19][26]
      • Diploaspis muelleri Poschmann, Anderson & Dunlop, 2005—Devonian[16]
      • Diploaspis praecursor Selden, Lamsdell & Liu 2015—Silurian[13]
    • Dvulikiaspis Marshall, Lamsdell, Shpinev & Braddy, 2014
      • Dvulikiaspis menneri (Novojilov, 1959) (formerly known as ‘Tylopterella’ menneri)—Devonian[14]
    • Forfarella Dunlop, Anderson & Braddy, 1999
      • Forfarella mitchelli Dunlop, Anderson & Braddy, 1999—Devonian[2]
    • Heteroaspis Størmer, 1972
      • Heteroaspis stoermeri Størmer, 1972 (formerly known as ‘Eurypterus’ stoermeri)—Devonian[19]
    • Hoplitaspis Lamsdell, Gunderson & Meyer, 2019
      • Hoplitaspis hiawathai Lamsdell, Gunderson & Meyer, 2019—Ordovician[11]
    • Loganamaraspis Tetlie & Braddy, 2004
      • Loganamaraspis dunlopi Tetlie & Braddy, 2004—Silurian[3]
    • Nahlyostaspis Marshall, Lamsdell, Shpinev & Braddy, 2014
      • Nahlyostaspis bergstroemi Marshall, Lamsdell, Shpinev & Braddy, 2014—Devonian[14]
    • Octoberaspis Dunlop, 2002[15]
      • Octoberaspis ushakovi Dunlop, 2002—Devonian[15]
    • Skrytyaspis Marshall, Lamsdell, Shpinev & Braddy, 2014
      • Skrytyaspis andersoni Marshall, Lamsdell, Shpinev & Braddy, 2014—Devonian[14]

References

  1. ^ a b c d e f g h i j k l m n o p Jason A. Dunlop, Lyall I. Anderson & Simon J. Braddy (2004). "A redescription of Chasmataspis laurencii Caster & Brooks (Chelicerata: Chasmataspidida) from the Middle Ordovician of Tennessee, USA, with remarks on chasmataspid phylogeny" (PDF). Transactions of the Royal Society of Edinburgh: Earth Sciences. 94 (4): 207–225. doi:10.1017/S0263593300000626. S2CID 130713268.
  2. ^ a b c Jason A. Dunlop, L. I. Anderson & S. J. Braddy (1999). "A new chasmataspid (Chelicerata: Chasmataspida) from the Lower Devonian of the Midland Valley of Scotland" (PDF). Transactions of the Royal Society of Edinburgh: Earth Sciences. 89 (3): 161–165. doi:10.1017/s0263593300007100. S2CID 130344322.
  3. ^ a b c d e f g O. Erik Tetlie & Simon J. Braddy (2003). "The first Silurian chasmataspid, Loganamaraspis dunlopi gen. et sp. nov. (Chelicerata: Chasmataspidida) from Lesmahagow, Scotland, and its implications for eurypterid phylogeny". Transactions of the Royal Society of Edinburgh: Earth Sciences. 94 (3): 227–234. doi:10.1017/S0263593300000638. S2CID 73596575.
  4. ^ a b c d Garwood, Russell J.; Dunlop, Jason A. (2014). "Three-dimensional reconstruction and the phylogeny of extinct chelicerate orders". PeerJ. 2: e641. doi:10.7717/peerj.641. PMC 4232842. PMID 25405073.
  5. ^ a b c d e Lamsdell, James C. (2013-01-01). "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.
  6. ^ a b c d e 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 1463-6409. S2CID 55264483.
  7. ^ a b c d 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. doi:10.1007/s00114-015-1312-5. ISSN 0028-1042. PMID 26391849. S2CID 8153035.
  8. ^ a b c d Lamsdell, James C. (2016). Zhang, Xi-Guang (ed.). "Horseshoe crab phylogeny and independent colonizations of fresh water: ecological invasion as a driver for morphological innovation". Palaeontology. 59 (2): 181–194. doi:10.1111/pala.12220. S2CID 85553811.
  9. ^ a b c 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, online at http://wsc.nmbe.ch, version 18.5 http://www.wsc.nmbe.ch/resources/fossils/Fossils18.5.pdf (PDF).
  10. ^ a b c d e f g h i j k l m Dunlop, Jason A.; Lamsdell, James C. (2017). "Segmentation and tagmosis in Chelicerata". Arthropod Structure & Development. 46 (3): 395–418. doi:10.1016/j.asd.2016.05.002. ISSN 1467-8039. PMID 27240897.
  11. ^ a b c d e f g h i j k l m n o Lamsdell, James C.; Gunderson, Gerald O.; Meyer, Ronald C. (2019-01-08). "A common arthropod from the Late Ordovician Big Hill Lagerstätte (Michigan) reveals an unexpected ecological diversity within Chasmataspidida". BMC Evolutionary Biology. 19 (1): 8. doi:10.1186/s12862-018-1329-4. ISSN 1471-2148. PMC 6325806. PMID 30621579.
  12. ^ a b c Lamsdell, James C. (2019). "A chasmataspidid affinity for the putative xiphosuran Kiaeria Størmer, 1934". Paläontologische Zeitschrift. 94 (3): 449–453. doi:10.1007/s12542-019-00493-8. S2CID 207914022.
  13. ^ a b c d e f James C. Lamsdell; Derek E. G. Briggs (2017). "The first diploaspidid (Chelicerata: Chasmataspidida) from North America (Silurian, Bertie Group, New York State) is the oldest species of Diploaspis" (PDF). Geological Magazine. 154 (1): 175–180. Bibcode:2017GeoM..154..175L. doi:10.1017/S0016756816000662. S2CID 85560431. Archived from the original (PDF) on 2020-02-27.
  14. ^ a b c d e f g h i j Marshall, David J.; Lamsdell, James C.; Shpinev, Evgeniy; Braddy, Simon J. (2014). "A diverse chasmataspidid (Arthropoda: Chelicerata) fauna from the Early Devonian (Lochkovian) of Siberia". Palaeontology. 57 (3): 631–655. doi:10.1111/pala.12080. ISSN 1475-4983. S2CID 84434367.
  15. ^ a b c d e f Jason A. Dunlop (2002). "Arthropods from the Lower Devonian Severnaya Zemlya Formation of October Revolution Island, Russia" (PDF). Geodiversitas. 24 (2): 349–379.
  16. ^ a b c d Markus Poschmann, Lyall I. Anderson & Jason A. Dunlop (2005). "Chelicerate arthropods, including the oldest phalangiotarbid arachnid, from the Early Devonian (Siegenian) of the Rhenish Massif, Germany" (PDF). Journal of Paleontology. 79 (1): 110–124. doi:10.1666/0022-3360(2005)079<0110:CAITOP>2.0.CO;2. S2CID 129082668.
  17. ^ a b c Lyall I. Anderson, Jason A. Dunlop & Nigel H. Trewin (2000). "A Middle Devonian chasmataspid arthropod from Achanarras Quarry, Caithness, Scotland" (PDF). Scottish Journal of Geology. 36 (2): 151–158. doi:10.1144/sjg36020151. S2CID 140167776.
  18. ^ Kenneth E. Caster and H. K. Brooks (1956). "New fossils from the Canadian–Chazan (Ordovician) hiatus in Tennessee". Bulletins of American Paleontology. 36: 157–199.
  19. ^ a b c d Leif Størmer (1972). "Arthropods from the Lower Devonian (Lower Emsian) of Alken an der Mosel, Germany. Part 2: Xiphosura". Senckenbergiana Lethaea. 53: 1–29.
  20. ^ Shultz, Jeffrey W. (2007-06-01). "A phylogenetic analysis of the arachnid orders based on morphological characters". Zoological Journal of the Linnean Society. 150 (2): 221–265. doi:10.1111/j.1096-3642.2007.00284.x. ISSN 0024-4082.
  21. ^ Lamsdell, James C.; Selden, Paul (2013). "Babes in the wood – a unique window into sea scorpion ontogeny". BMC Evolutionary Biology. 13 (98): 1–46. doi:10.1186/1471-2148-13-98. PMC 3679797. PMID 23663507.
  22. ^ Moore, Rachel A.; Briggs, Derek E. G.; Bartels, Christoph (2005). "A new specimen ofWeinbergina opitzi (Chelicerata: Xiphosura) from the Lower Devonian Hunsriick Slate, Germany". Paläontologische Zeitschrift. 79 (3): 399–408. doi:10.1007/BF02991931. ISSN 0031-0220. S2CID 84994966.
  23. ^ Legg, David A. (2014). "Sanctacaris uncata: the oldest chelicerate (Arthropoda)". Naturwissenschaften. 101 (12): 1065–1073. doi:10.1007/s00114-014-1245-4. ISSN 0028-1042. PMID 25296691. S2CID 15290784.
  24. ^ Aria, Cédric; Caron, Jean-Bernard (2017-12-21). "Mandibulate convergence in an armoured Cambrian stem chelicerate". BMC Evolutionary Biology. 17 (1): 261. doi:10.1186/s12862-017-1088-7. ISSN 1471-2148. PMC 5738823. PMID 29262772.
  25. ^ Aria, Cédric; Caron, Jean-Bernard (2019). "A middle Cambrian arthropod with chelicerae and proto-book gills". Nature. 573 (7775): 586–589. doi:10.1038/s41586-019-1525-4. ISSN 1476-4687. PMID 31511691. S2CID 202550431.
  26. ^ Dunlop, Jason A.; Poschmann, Markus; Anderson, Lyall I. (December 2001). "On the Emsian (Early Devonian) arthropods of the Rhenish Slate Mountains: 3. The chasmataspididDiploaspis". PalZ. 75 (2): 253–269. doi:10.1007/BF02988018. ISSN 0031-0220. S2CID 128479601.
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Chasmataspidida: Brief Summary ( anglais )

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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 hindpart (postabdomen) each comprising 4 and 9 segments respectively. There is some debate about whether they form a natural (i.e. monophyletic) group.

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Chasmataspidida ( italien )

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I casmataspididi (Chasmataspidida), a volte indicati come casmataspidi (Chasmataspida), sono un gruppo di artropodi chelicerati estinti, forse imparentati con gli xifosuri, gli euripteridi o gli aracnidi. Vissero tra l'Ordoviciano medio e il Devoniano medio (circa 470 - 390 milioni di anni fa) e i loro resti fossili sono stati ritrovati in Europa, Nordamerica e Asia.

Descrizione

La maggior parte dei casmataspididi sono piccoli artropodi con una lunghezza del corpo non superiore a 3 centimetri, ma le specie ordoviciane erano eccezionalmente grandi, con lunghezze tra i 10 centimetri (Chasmataspis) e i 29 centimetri (Hoplitaspis).

Il corpo aerodinamico dei casmataspidi è composto da un prosoma rigido e da un opistosoma a 13 segmenti esterni. Come gli euripteridi, il lato dorsale del prosoma era coperto da un carapace rigido (scudo dorsale prosomale) che portava un paio di occhi laterali più grandi (presumibilmente composti) e un paio di piccoli ocelli mediani. I casmataspidi si distinguono facilmente dagli altri chelicerati per la suddivisione dei 13 segmenti opistosomiali in un preaddome allargato a 4 segmenti e un postaddome sottile a 9 segmenti. La tergite (esoscheletro dorsale) del primo segmento opistosomiale/preaddominale conserva come un elemento stretto noto come 'microtergite', che non è osservabile negli euripteridi. I tre segmenti preaddominali posteriori sono ben sviluppati, formando una sezione rigida chiamata "buckler". I segmenti postaddominali sono cilindrici e l'ultimo segmento termina con un telson simile a una spina o a una piastra, di solito relativamente corto.

Classificazione

I casmataspididi sono probabilmente imparentati con i limuli (Xiphosura) e/o con gli scorpioni di mare (Eurypterida). Studi più recenti suggeriscono che formino un clade (Dekatriata) con i gruppi Eurypterida e Arachnida. Alcuni studi indicano che i casmataspidi potrebbero non essere un gruppo monofiletico, ma forse un grado parafiletico di forme da cui nacquero gli euripteridi, o un gruppo parafiletico con acune forme più imparentate con gli xifosuri (Chasmataspis) e altre con gli euripteridi (Diploaspis e simili). Tuttavia, indagini più recenti indicherebbero una monofilia del gruppo, ponendolo alla base di un clade (Dekatriata) comprendente anche aracnidi ed euripteridi (Legg, 2014; Aria et al., 2017; Aria et al., 2019).

Bibliografia

  • Jason A. Dunlop, L. I. Anderson & S. J. Braddy (1999). "A new chasmataspid (Chelicerata: Chasmataspida) from the Lower Devonian of the Midland Valley of Scotland" (PDF). Transactions of the Royal Society of Edinburgh: Earth Sciences. 89 (3): 161–165. doi:10.1017/s0263593300007100.
  • O. Erik Tetlie & Simon J. Braddy (2003). "The first Silurian chasmataspid, Loganamaraspis dunlopi gen. et sp. nov. (Chelicerata: Chasmataspidida) from Lesmahagow, Scotland, and its implications for eurypterid phylogeny". Transactions of the Royal Society of Edinburgh: Earth Sciences. 94 (3): 227–234. doi:10.1017/S0263593300000638.
  • Jason A. Dunlop, Lyall I. Anderson & Simon J. Braddy (2004). "A redescription of Chasmataspis laurencii Caster & Brooks (Chelicerata: Chasmataspidida) from the Middle Ordovician of Tennessee, USA, with remarks on chasmataspid phylogeny". Transactions of the Royal Society of Edinburgh: Earth Sciences. 94 (4): 207–225. doi:10.1017/S0263593300000626.
  • 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.
  • Garwood, Russell J.; Dunlop, Jason A. (2014). "Three-dimensional reconstruction and the phylogeny of extinct chelicerate orders". PeerJ. 2: e641. doi:10.7717/peerj.641. PMC 4232842. PMID 25405073.
  • Legg, David A. (2014). "Sanctacaris uncata: the oldest chelicerate (Arthropoda)". Naturwissenschaften. 101 (12): 1065–1073. doi:10.1007/s00114-014-1245-4.
  • 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. doi:10.1007/s00114-015-1312-5. ISSN 0028-1042. PMID 26391849. S2CID 8153035.
  • 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 1463-6409.
  • Lamsdell, James C. (2016). Zhang, Xi-Guang (ed.). "Horseshoe crab phylogeny and independent colonizations of fresh water: ecological invasion as a driver for morphological innovation". Palaeontology. 59 (2): 181–194. doi:10.1111/pala.12220.
  • Aria, Cédric; Caron, Jean-Bernard (2017). "Mandibulate convergence in an armoured Cambrian stem chelicerate". BMC Evolutionary Biology. 17 (1): 261. doi:10.1186/s12862-017-1088-7. ISSN 1471-2148. PMC 5738823. PMID 29262772.
  • Aria, Cédric; Caron, Jean-Bernard (2019). "A middle Cambrian arthropod with chelicerae and proto-book gills". Nature. 573 (7775): 586–589.
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Chasmataspidida: Brief Summary ( italien )

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I casmataspididi (Chasmataspidida), a volte indicati come casmataspidi (Chasmataspida), sono un gruppo di artropodi chelicerati estinti, forse imparentati con gli xifosuri, gli euripteridi o gli aracnidi. Vissero tra l'Ordoviciano medio e il Devoniano medio (circa 470 - 390 milioni di anni fa) e i loro resti fossili sono stati ritrovati in Europa, Nordamerica e Asia.

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Chasmataspidida ( vietnamien )

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Biểu tượng mũi tên dịch thuật
Bài này là một bản dịch thô từ ngôn ngữ khác. Đây có thể là kết quả của máy tính hoặc của người chưa thông thạo dịch thuật. Xin hãy giúp tăng chất lượng bản dịch.

Chasmataspidida (thường được gọi không chính thức là chasmataspids ) là một nhóm đã tuyệt chủng hiếm động vật chân kìm vật chân đốt.Chasmataspids có lẽ liên quan đến cua móng ngựa (lớp đuôi kiếm) và / hoặc bọ cạp biển (Eurypterida). Thật vậy, các loài đầu tiên được phát hiện đều được cho là bất thường cua móng ngựa hóa thạch, trong khi các loài này sau đó được thường dựa trên các mẫu ban đầu xác định nhầm là eurypterids. Có một số bằng chứng cho thấy chasmataspids đã có mặt trong thời gian cuối Cambri và nhóm này được biết đến rải rác trong các hóa thạch thông qua vào giữa Devon. Chasmataspids có thể dễ dàng nhận thấy nhất bởi có một bụng chia thành một bộ phận trước ngắn (hoặc mesosoma) và một hindpart còn (hoặc metastoma) gồm chín đoạn. Có một số cuộc tranh luận về việc liệu chúng hình thành một cách tự nhiên (tức là đơn ngành nhóm).

Nội dung

Chi [ sửa ]

Chasmataspis [ sửa ]

Các chasmataspid đầu tiên được phát hiện là Chasmataspis laurencii , được mô tả bởi các nhà cổ sinh học người Mỹ Kenneth E. Caster và HK Brooks. Những hóa thạch Ordovic đến từ các trang web của Douglas Đầm ở Tennessee, Mỹ. Họ là những lớp đuôi kiếm giống như hầu hết các loài chasmataspid nổi tiếng, với một headshield hình móng ngựa. Caster & Brooks lớn lên trong một gia đình mới, Chasmataspididae, để chứa các mẫu vật. Các loài được redescribed Jason Dunlop và đồng nghiệp.

Diploaspis [ sửa ]

Các loài tiếp theo được phát hiện là Diploaspis casteriHeteroaspis novojilovi ; cả hai được mô tả bởi các cổ sinh vật học Na Uy Leif Stormer từ Devon sớm Alken an der Mosel ở Đức.

Một sửa đổi bởi Markus Poschmann và đồng nghiệp công nhận H. novojilovi như một từ đồng nghĩa của D. casteri . Hai chi xuất hiện để thực sự được biến thể preservational của cùng một loài. Poschmann et al. . Cũng mô tả một loài thứ hai là Diploaspis muelleri .

Forfarella [ sửa ]

Forfarella mitchelli từ Devon đầu của khu vực Forfar trong thung lũng Midland của Scotland đã được mô tả bởi Jason Dunlop và đồng nghiệp; . Mặc dù các hóa thạch đã thực sự được công nhận là một chasmataspid và tạm nhãn như vậy một vài năm trước đây bởi Charles Waterston Forfarella mitchelli không phải là rất tốt bảo quản, nhưng không hiển thị các kế hoạch cơ chasmataspid đặc trưng.

Acahanarraspis [ sửa ]

Các chasmataspid stratigraphically út là Achanarraspis reedi , được mô tả bởi Lyall Anderson và cộng sự từ mỏ đá giữa Devon Achanarras ở Caithness, Scotland; một hóa thạch nổi tiếng địa phương.

Octoberaspis [ sửa ]

Chasmataspids bảo quản tốt đã được thu hồi từ Devon sớm Đảo Cách mạng tháng Mười, một phần của nhóm Severnaya Zemlya ở Bắc Cực của Nga. Nguyên mô tả ngắn gọn như eurypterids, họ đã đặt tên chính thức là Octoberaspis ushakovi Jason Dunlop.

Loganamaraspis [ sửa ]

Các chasmataspid phát hiện gần đây nhất được công nhận là Loganamaraspis dunlopi từ một địa phương hóa thạch Silur nổi tiếng gần Lesmahagow ở Scotland. Được mô tả bởi Erik Tetlie và Simon Braddy, nó sẽ được đặt Diploaspididae, nhưng hiểu là phần trung gian hơn trong hình thức giữa các ChasmataspisDiploaspis kế hoạch cơ thể.

Phân loại [ sửa ]

  • † Chasmataspidida Caster & Brooks, 1956
    • = † Diploaspidida Simonetta & Delle Cave, 1978
  • † Chasmataspididae Caster & Brooks, 1956
    • Chasmataspis Caster & Brooks, 1956
      • Chasmataspis laurencii Caster & Brooks, 1956 - Ordovic Tennessee, USA
  • † Diploaspididae Stormer, 1972
    • = † Heteroaspididae Stormer, 1972
    • Achanarraspis Anderson, Dunlop & Trewin, 2000
      • Achanarraspis reedi Anderson, Dunlop & Trewin, 2000 - Devon của Scotland
    • Diploaspis Stormer, 1972
      • = Heteroaspis Stormer, 1972
      • Diploaspis casteri Stormer, 1972 - Devon của Đức
        • = Heteroaspis novojilovi Stormer, 1972 - Devon của Đức
      • Diploaspis muelleri Poschmann, Anderson & Dunlop, 2005 - Devon của Đức
    • Forfarella Dunlop, Anderson & Braddy, 1999
      • Forfarella mitchelli Dunlop, Anderson & Braddy, 1999 - Devon của Scotland
    • Loganamaraspis Tetlie & Braddy, 2004
      • Loganamaraspis dunlopi Tetlie & Braddy, 2004 - Silur Scotland
    • Octoberaspis Dunlop, 2002
      • Octoberaspis ushakovi Dunlop, 2002 - Devon của Severnya Zemlya, Nga
  • Diploaspidae incertae sedis
    • † ' Eurypterus '
      • † ' Eurypterus ' stoermeri Novojilov, 1959 - Devon của Siberia

Tham khảo

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Chasmataspidida: Brief Summary ( vietnamien )

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Chasmataspidida (thường được gọi không chính thức là chasmataspids ) là một nhóm đã tuyệt chủng hiếm động vật chân kìm vật chân đốt.Chasmataspids có lẽ liên quan đến cua móng ngựa (lớp đuôi kiếm) và / hoặc bọ cạp biển (Eurypterida). Thật vậy, các loài đầu tiên được phát hiện đều được cho là bất thường cua móng ngựa hóa thạch, trong khi các loài này sau đó được thường dựa trên các mẫu ban đầu xác định nhầm là eurypterids. Có một số bằng chứng cho thấy chasmataspids đã có mặt trong thời gian cuối Cambri và nhóm này được biết đến rải rác trong các hóa thạch thông qua vào giữa Devon. Chasmataspids có thể dễ dàng nhận thấy nhất bởi có một bụng chia thành một bộ phận trước ngắn (hoặc mesosoma) và một hindpart còn (hoặc metastoma) gồm chín đoạn. Có một số cuộc tranh luận về việc liệu chúng hình thành một cách tự nhiên (tức là đơn ngành nhóm).

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