Cheloniellida
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2008-02-29T13:34:07Z
Eubot
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Removed taxobox colour. See [[User:Eubot/Removing colours from taxoboxen]].
{{Taxobox
| name = Cheloniellida
| image =
| image_caption = Reconstruction of ''Cheloniellon calmani'' Broili, 1932.
| regnum = [[Animal]]ia
| phylum = [[Arthropoda]]
| classis = '''Cheloniellida'''
| classis_authority = [[Broili]], 1932
| subdivision_ranks = Genera
| subdivision =
See text for list.
}}
The '''Cheloniellida''' Broili, 1932 are an unranked taxon (usually referred to as a class or order) of extinct [[Paleozoic]] [[Arthropoda|arthropods]], currently (Dunlop & Selden, 1997; Dunlop, 2002) thought to be a member of the [[Arachnomorpha]] and related to the [[Chelicerata]] and the [[Trilobita]], while not included in any of those.
There are six included genera, dating from [[Ordovician]], [[Silurian]] and [[Devonian]].
==Included genera==
*''Cheloniellon'' Broili, 1932 - Lower Devonian, Germany
*''Duslia'' Jahn, 1893 - Upper Ordovician, Czech Republic
*''Neostrabops'' Caster & Macke, 1952 - Upper Ordovician, USA
*''Paraduslia'' Dunlop, 2002 - Lower Devonian, Russia.
*''Pseudarthron'' Selden & White, 1984 - Upper Silurian
*''Triopus'' Barrande, 1872 - Upper Ordovician
==Relationships - varied proposals==
"Originally ''Cheloniellon'' was believed to be similar to trilobites (Broili 1932), though subsequent authors have suggested suggested that it is related to trilobites and Cambrian “merostomoids” (Størmer 1944), that it is a late representative of a trilobitomorph
group giving rise to Chelicerata (Stürmer & Bergström 1978), that it is related to “loricate”
crustaceans (Delle Cave & Simonetta 1991) or that it is the sister group to Chelicerata (Wills et al. 1995; Dunlop & Selden 1997)." [Account by Dunlop, 2002].
*Class Cheloniellida, sister group to class [[Crustacea]] (Boudreaux, 1979).
*Order Cheloniellida in subclass [[Petalopleura]] in class [[Artiopoda]], this being sister to class [[Marellomorpha]] (Hou & Bergström, 1997).
*One of the five major taxa of the [[Arachnomorpha]], sister group to the Chelicerata. The other three are [[Trilobita]], [[Aglaspidida]] and [[Strabopida]] (Dunlop & Selden 1997, repeated by Budd, 1997).
==References==
*Boudreaux H. B. (1979). Arthropod phylogeny with special reference to insects. John Willey & sons, New York, Chichester, Brisbane, Toronto. 320 pp.
*Budd, Graham E. (1997). Stem Group Arthropods from the Lower Cambrian Sirius Passet Fauna of North Greenland. In Fortey, R.A.; Thomas R.H. (eds.): Arthropod Relationships. Systematics Association Special Volume Series 55.
*Jason A. Dunlop and Paul A. Selden. (1997).The early history and phylogeny of the chelicerates. Arthropod Relationships, pp. 237-245, R. A. Fortey & R. H. Thomas (eds.), Systematics Association Special Volume Series 55.
*Xianguang Hou & Bergström J. (1997). Arthropods of the Lower Cambrian Chengliang fauna, southwest China. Fossils & Strata, No.45: 1-116
[[Category:Prehistoric arthropods]]