Bassleroceras

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:Genus: '''''Bassleroceras'''''
:Genus: '''''Bassleroceras'''''
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'''''Bassleroceras''''' is a genus of nautiloid cephalopod from the early Ordovician, intermediary between the more primitive ellesmeroceratids and more evolved tarphycerids .
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'''''Bassleroceras''''' is a genus of nautiloid cephalopod from the early Ordovician, intermediary between the more primitive ellesmeroceratids and more evolved tarphycerids.
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''Bassleroceras'' has an upwardly curved, exogastric, cyrotoconic shell, around 10- 15cm in the adult; much like the rocker of a rocking chair. The section is somewhat compressed, higher than wide; dorsum, on the inside curvature broadly rounded; venter, on the outside curvature narrowly rounded, like a keel.  Septa close spaced, chambers short. Siphuncle ventral.
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''Bassleroceras'' fills the evolutionary gap between the ancestral orthoconic [[Ellesmeroceratidae|ellesmoroceratids]]) and the coiled [[Tarphycerida|tarphycerids]]. As such it can be called a "missing link".
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The family [[Bassleroceratidae]], including ''Bassleroceras'', has been placed either in the ancestral group or in the descendant group. W.M. Furnish and Brian Glenister, writing in the ''Treatise on Invertebrate Paleontology'', Part L, assigned the Blassleroceratidae to the Ellesmerocerida. Rousseau Flower, 1950, in ''A classification of the Cephalopoda'', assigned the Bassleroceratidae to its own order, the Basslerocerida, but later in 1976 in ''Ordovician Cephalopod Faunas and Their Role in Classification'' included them in the Tarphycerida.  
'''Credits'''
'''Credits'''
JHM 0/4/13
JHM 0/4/13

Revision as of 21:55, 4 September 2013

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