Phyllocerida

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== Evolutionary History and Phylogeny==
== Evolutionary History and Phylogeny==
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The Ussuritidae gave rise to the Discophyllitidae at the beginning of the Late Triassic (Carnian), but continued to the end of the period. The Discophyllitidae, which also continued well into the Raetian, give rise to the mostly Jurassic and Cretaceous Phylloceratidae, which forms the bulk of the order.  
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The Ussuritidae gave rise to the Discophyllitidae at the beginning of the Late Triassic (Carnian), but continued to the end of the period. The Discophyllitidae, which also continued well into the Raetian, give rise to the mostly Jurassic and Cretaceous Phylloceratidae, which forms the bulk of the order. The Ussuritidae or Discophyllitidae also gave rise to the Lytocerida which is the source of most of the Jurassic ammonitids
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The Phylloceratidae, may have given rise to the Juraphyllitidae, a small family confined to the Lower Jurassic.  However the Juraphyllitidae may have evolved separately from the Discophyllitidae. Otherwise the Phylloceratidae are the only phyllocerids of the post Triassic.
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The Phylloceratidae may have given rise to the Juraphyllitidae, a small family confined to the Lower Jurassic, although the Juraphyllitidae may have evolved separately from the Discophyllitidae, and to certain of the Ammonitida. Otherwise the Phylloceratidae are the only phylloceratids of the post Triassic. The Phylloceratidae gave rise to the Psiloceratidae (Psilocerataceae, Ammonitida) near the beginning of the Jurassic and to the Desmoceratidae (Desmocerataceae) in the Lower Cretaceous (Valanginian) which is the root stock for the principal Cretaceous ammonitids
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The Phlloceratidae gave rise to  the [[Lytocerida]] and to some of the [[Ammonitida]]. It gave rise to the Psiloceratidae (Psilocerataceae, Ammonitida) at the beginning of the Jurassic if not in the latest Triassic; to the Lytoceratidae (Lytocerataceae, Lytoceratida,) in the early Lower Jurassic (Sinemurian), which is the source for most of the Jurassic ammonitids, and to the Desmoceratidae (Desmocerataceae) in the Lower Cretaceous (Valanginian) which is the root stock for the principal Cretaceous ammonitids.
 
==Principal Morphologies==
==Principal Morphologies==

Revision as of 12:28, 8 August 2010

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