Piloceratidae

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:Class: [[Cephalopoda]]
:Class: [[Cephalopoda]]
:Subclass: [[Nautiloidea]]
:Subclass: [[Nautiloidea]]
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:Superorder: [[Endocerida|Endoceratoidea]]Wade 1988
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:Superorder: [[Endocerida|Endoceratoidea]] Wade 1988
:Order: [[Endocerida]] Teichert 1933
:Order: [[Endocerida]] Teichert 1933
:Family: Piloceratidae. Miller 1889
: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.
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 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 derived from [[Proterocameroceratidae|proterocameroceratids]], possibly from ''[[Kirkoceras]]'' or perhaps ''[[Clitendoceras]]'',  and make their first appearance 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.   
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 .  
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 .  

Latest revision as of 17:14, 18 September 2013

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