Cyclida
| Cyclida Temporal range:
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| Restoration of Schramine (top) and Opolanka (bottom) | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Superclass: | Multicrustacea |
| Order: | †Cyclida Glaessner, 1928 |
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Cyclida (formerly Cycloidea, and so sometimes known as cycloids) is an extinct order of crab-like fossil arthropods that lived from the Carboniferous to the Cretaceous. Their classification is uncertain, but they are generally interpreted as crustaceans, likely belonging to the superclass Multicrustacea.
Description
Cycloids have a "striking"[1] resemblance to crabs, and are thought to have inhabited a similar ecological niche, and to have been driven to extinction when crabs became widespread and diverse.[1] The largest members are over 6 centimetres (2.4 in) across the carapace.[2] Their gills are often preserved in three dimensions, and do not resemble those of other crustaceans.[2] Cycloid taxa differ in the number of walking legs, in the form of the mouthparts and in other significant ways.[2]
Affinities
There is considerable debate about the placement of cycloids within the Arthropoda. While they are generally considered to be crustaceans of some kind, doubts have been expressed about the homology of cycloids' respiratory structures with those of other crustaceans, and parallels drawn instead with chelicerates.[3]
The first description of a cycloid was in the 1836 treatise Illustrations of the Geology of Yorkshire by John Phillips,[4][5] where Phillips described "Agnostus ? radialis" among the trilobites, with the text "ribs radiating, with acute puncta; abdomen mucronate".[6] In 1838, Hermann von Meyer described a species of trilobite, albeit in the genus Limulus, and later transferred it to a new genus, Halicyne, recognising that it was something different.[4] In 1841, Laurent-Guillaume de Koninck transferred Phillips' species to a new genus, Cyclus, away from the trilobites, although he later described a second species of Cyclus which was later recognised as the hypostome of a trilobite.[4] Cycloids were later considered to be members of the Xiphosura, true crabs, and branchiurans.[7]
In an unpublished dissertation, Neil D. L. Clark proposed in 1989 that cycloids were copepods.[7] In 1997, Frederick Schram and his co-authors[4] classified them as the sister group to copepods, within the Maxillopoda,[3] and in 2008, Jerzy Dzik[2] placed them as an order within the maxillopod suborder Branchiura,[3] which previously contained only the modern fish lice. A 2020 study based on well preserved remains of Americlus from the Carboniferous of North America found that Cyclida had the greatest affinities with Copepoda and Malacostraca, and likely represented an independent branch of the Multicrustacea.[8]
Taxa and stratigraphy
Cycloids are known from deposits ranging from Carboniferous (Cyclus spp.) to Maastrichtian (Maastrichtocaris rostrata).[2] They are one of only three groups of "generally Palaeozoic" arthropods to survive the Permian–Triassic extinction event, the others being the freshwater-living Euthycarcinoida and the marine Thylacocephala.[2]
Families and genera
After Feldmann and Schweitzer, 2019.[9]
- Family Schraminidae Dzik, 2008
- Schramine Dzik, 2008[2] comprises five species from the Carboniferous of North America and the Early Triassic of Madagascar, some of which were formerly included in Halicyne.
- Family Cyclidae Packard, 1885
- Cyclus de Koninck, 1841 contains 17 species found in Carboniferous deposits of Europe, Asia and North America
- Uralocyclus Mychko & Alekseev, 2018 contains a single species from the Earliest Permian of Chelyabinsk, Russia
- Family Halicynidae Gall & Grauvogel, 1967
- Halicyne von Meyer, 1844 contains six species from the Middle Triassic of Europe.[2]
- Carcinaspides Glaessner, 1969 contains a single species found in limestone rocks in the Isar valley of Bavaria (Germany) and is probably of Mid to Late Triassic age.[2]
- Juracyclus Schweigert, 2007 comprises a single species found in the Early Jurassic Posidonienschiefer near Tübingen, southern Germany.[1]
- Opolanka Dzik, 2008[2] contains a single species found in Late Triassic rocks at Krasiejów in Poland.[2]
- Family Americlidae Dzik, 2008
- Americlus contains six species from the Carboniferous of Europe and North America including A. americanus (formerly Cyclus americanus),[2] a well known species from Mazon Creek.[4]
- Yunnanocyclus Feldmann, Schweitzer & Hu, 2017 single species known from the Middle Triassic of China
- Family Alsasuacaridae van Bakel, Jagt, Fraaije & Artal, 2011
- Alsasuacaris van Bakel, Jagt, Fraaije & Artal, 2011 known from a single species found in late Albian to early Cenomanian (Cretaceous) rocks near Alsasua (Navarre, Spain).[10]
- Maastrichtocaris rostrata is found in Maastrichtian (late Cretaceous) rocks from that period's type locality in the southern Netherlands, youngest known cyclidan.[7]
- Family Hemitrochiscidae Trauth, 1918
- Apionicon Schram, Vonk & Hof, 1997 is known from a single species found in Upper Carboniferous (Pennsylvanian) shales in Illinois, including Mazon Creek.[4]
- Cyclocarcinides Glaessner, 1969 comprises 5 species known from the Upper Triassic of Europe
- Hemitrochiscus Schauroth, 1854 known from one species found in Late Permian dolomite near Wünschendorf/Elster (Germany).[2]
- Oonocarcinus Gemmellaro, 1890 is known from 3 species from the Permian of Sicily and 1 species from the Late Triassic of Slovakia
- Paraprosopon Gemmellaro, 1890 is known from one species from the Permian of Sicily (Italy).[2]
- Skuinocyclus Mychko & Alekseev, 2018 comprises one species from the earliest Permian of Bashkortostan, Russsia
Further reading
- Alpheus Spring Packard (1885). "The Syncarida, a group of Carboniferous Crustacea". The American Naturalist. 19 (7): 700–703. doi:10.1086/274005. JSTOR 2450109.
References
- ^ a b c Günter Schweigert (2007). "Juracyclus posidoniae n. gen. and sp., the first cycloid arthropod from the Jurassic" (PDF). Journal of Paleontology. 81 (1): 213–215. CiteSeerX 10.1.1.490.9065. doi:10.1666/0022-3360(2007)81[213:JPNGAS]2.0.CO;2.
- ^ a b c d e f g h i j k l m n Jerzy Dzik (2008). "Gill structure and relationships of the Triassic cycloid crustaceans" (PDF). Journal of Morphology. 269 (12): 1501–1519. doi:10.1002/jmor.10663. PMID 18690662. S2CID 17617567.
- ^ a b c Geoff A. Boxshall; Damià Jaume (2009). "Exopodites, epipodites and gills in crustaceans" (PDF). Arthropod Systematics & Phylogeny. 67 (2): 229–254. Archived from the original (PDF) on 2019-04-26. Retrieved 2011-03-24.
- ^ a b c d e f Frederick R. Schram; Ronald Vonk; Cees H. J. Hof (1997). "Mazon Creek Cycloidea". Journal of Paleontology. 71 (2): 261–284. doi:10.1017/S0022336000039172. JSTOR 1306460.
- ^ Frederick R. Schram; Arjan C. Boere; Natalie Thomas (2006). "Cycloids of the Mississippian Bear Gulch limestone of central Montana" (PDF). Contributions in Science. 504: 1–8. doi:10.5962/p.210567. S2CID 160017485. Archived from the original (PDF) on 2010-07-21. Retrieved 2011-03-24.
- ^ John Phillips (1836). Part 2. The Mountain Limestone District. Illustrations of the Geology of Yorkshire. London: John Murray.
- ^ a b c René H. B. Fraaije; Frederick R. Schram; Ronald Vonk (2003). "Maastrichtiocaris rostratus new genus and species, the first Cretaceous cycloid". Journal of Paleontology. 77 (2): 386–388. doi:10.1666/0022-3360(2003)077<0386:MRNGAS>2.0.CO;2. JSTOR 4094744.
- ^ Redescription of Americlus rankini (Woodward, 1868) (Pancrustacea: Cyclida: Americlidae) and interpretation of its systematic placement, morphology, and paleoecology Neil D L Clark, Rodney M Feldmann, Frederick R Schram, Carrie E Schweitzer Journal of Crustacean Biology, Volume 40, Issue 2, March 2020, Pages 181–193, https://doi.org/10.1093/jcbiol/ruaa001
- ^ Feldmann, Rodney M; Schweitzer, Carrie E (2019-09-18). "The enigmatic Cyclida (Pancrustacea): morphological terminology and family-level classification". Journal of Crustacean Biology. 39 (5): 617–633. doi:10.1093/jcbiol/ruz053. ISSN 0278-0372.
- ^ Barry W. M. van Bakel; John W. M. Jagt; René H. B. Fraaije & Pedro Artal (2011). "A new family, genus and species of cyclid (Crustacea, Branchiura, Cyclida) from mid-Cretaceous reefal deposits in northern Spain" (PDF). Bulletin of the Mizunami Fossil Museum. 37: 47–49. Archived from the original (PDF) on 2011-07-21. Retrieved 2011-03-24.