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Articulata
Articulata
1. (phylum Brachiopoda) A class of brachiopods in which the calcareous valves are impunctate, punctate, or pseudo-punctate. The fibrous or prismatic secondary layer and non-fibrous primary layer are well differentiated. Hinge teeth and dental sockets are developed. Lophophore support is formed from modifications of socket ridges to give crura, loops, or spires. The alimentary canal ends blindly. Articulate brachiopods first appeared in the Lower Cambrian. There are six orders, with 37 super families. 2. (subphylum Crinozoa, class Crinoidea) A subclass containing all living, stalked crinoids, plus the feather stars, which are identified by the arrangement of the skeletal plates forming the calyx. Articulation between the radial and brachial plates, and in the majority of brachials, is muscular, with a well-developed fulcral ridge. The arms are always uniserial. All post-Palaeozoic crinoids belong to the Articulata. |
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MICHAEL ALLABY. "Articulata." A Dictionary of Zoology. 1999. Encyclopedia.com. 30 May. 2012 <http://www.encyclopedia.com>. MICHAEL ALLABY. "Articulata." A Dictionary of Zoology. 1999. Encyclopedia.com. (May 30, 2012). http://www.encyclopedia.com/doc/1O8-Articulata.html MICHAEL ALLABY. "Articulata." A Dictionary of Zoology. 1999. Retrieved May 30, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O8-Articulata.html |
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Articulata
Articulata
1. (phylum Brachiopoda) A class of brachiopods, existing from the Lower Cambrian to the present day, in which the shell is calcareous and comprises valves hinged by teeth in one valve and sockets in the other. The pedicle is of a horny material. Their main radiation was in the early Ordovician; of the 7 orders present in the Palaeozoic, 3 are still extant. 2. (sea lilies; subphylum Crinozoa, class Crinoidea) Subclass of sea lilies (crinoids) in which the basal plates are small or strongly reduced. Articulation between the radial and brachial plates, and in the majority of brachials, is muscular, with a well-developed fulcral ridge. The arms are always uniserial. All post-Palaeozoic crinoids belong to the Articulata. |
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Cite this article
AILSA ALLABY and MICHAEL ALLABY. "Articulata." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. 30 May. 2012 <http://www.encyclopedia.com>. AILSA ALLABY and MICHAEL ALLABY. "Articulata." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. (May 30, 2012). http://www.encyclopedia.com/doc/1O13-Articulata.html AILSA ALLABY and MICHAEL ALLABY. "Articulata." A Dictionary of Earth Sciences. 1999. Retrieved May 30, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O13-Articulata.html |
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