Pilocertidae

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m (Protected "Pilocertidae" ([move=sysop] (indefinite)))
(deleted to correct Piloceratidae)
 
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'''Systematic Paleontology'''
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moved text to [[Piloceratidae]] the proper name
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:Class: [[Cephalopoda]]
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:Subclass: [[Nautiloidea]]
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:Superorder: [[Endocerida|Endoceratoidea]]Wade 1988
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:Order: [[Endocerida]] Teichert 1933
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:Family: Piloceratidae. Miller 1889
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Piloceratidae, pilocerids for short, are a family of medium to moderately large, generally stout breviconic endocerids.  Pilocerid shells are moderately to strongly endogastric especially in the more juvenile portion of the phragmocone, rapidly expanded and typically compressed, but tend to straighten in the adult portion. The siphuncle is ventral often on the ventral margin and is large, compressed and rapidly expanding but generally not to the extent of the shell.  Simple endocones pack the apical end, septal necks and connecting rings where observed are respectively straight and long (holochoanitic) and thick.
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Pilocerids (Piloceratidae) are derived from [[Proterocameroceratidae|proterocameroceratids]], probably from ''[[Clitendoceras]]'' or similar form,  and make their first appearence in the Demingian Stage of the Lower Ordovician (Middle [[Canadian Epoch|Canadian]]; Lower Arenigian/= [[Floian]]) . They evolved rapidly into a number of diverse genera during the Demingian and persisted throughout the remainder of the Early Ordovician, contemporary with proterocameroceratids(fam), [[Tarphycerida|tarphycerids]], early [[Orthocerida|orthocerids]], and a variety of [[Ellesmerocerida|ellesmerocerids]] (orders) as well as other marine faunas of the time. 
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Pilocerids are postulated to have given rise to the generally straight and sometimes gigantic [[Endoceratidae]], although there is some evidence that the latter has its origin in the proterocameroceratids, and to the endogastrically gyroconic [[Cyrtendoceratidae|cyrtendocerids]]. Pilocerids dwindled in variety toward the end of the Early Ordovician (Canadian) at the end of which time became extinct, unless the Silurian ''Humeoceras'' is a true member and not a homeomorph . 
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Pilocerid genera include ''[[Piloceras]]'', ''[[Allopiloceras]]'', ''Bisonoceras'', ''[[Cassinoceras]]'', ''Dartenoceras'', ''Parapiloceras'', ''Mathewsonoceras'', ''Ovicoceras'', and ''Stenopiloceras'', many of which come from the middle and upper El Paso Group, Lower Ordovician, of Southern New Mexico and West Texas.
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==''Refs''==
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*Flower, R.H. and Kummel, B. 1950: A Classification of the Nautiloidea; Journal of Paleontology, V.25, No.5 pp 604-616, Sept 1950.
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*Flower, R. H. 1976: Ordovician Cephalopod Faunas and Their Role in Correlation; pp 523-552 in Basset, M.G. (ed) 1976. The Ordovician System: proceedings of a Palaeontological Association symposium.
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*Teichert, C, 1964: Endoceratoidea; Treatise on Invertebrate Paleontology, Part K, Mollusca 3; R.C. Moore, (ed). GSA & Univ. Kans.
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==Further sources==
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*Type and other specimens in the Rousseau Flower Collection at the New Mexico Museum of Natural History and Science, Albuquerque, N.M. U.S.A.  [http://www.nmnaturalhistory.org]
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*Piloceratidae in Wikipedia [http://en.wikipedia.org/wiki/Piloceratidae]
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*Pilocerids in Endicerida in Palaeos.com [http://www.palaeos.com/Invertebrates/Molluscs/Cyrtosoma/Cephalopoda/Endocerida.html]
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JM 11/15/09
JM 11/15/09

Latest revision as of 21:05, 15 November 2009

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