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<oai_dc:dc xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd">
  <dc:contributor>Roland Dreesen</dc:contributor>
  <dc:creator>Charles Sandberg</dc:creator>
  <dc:date>1984</dc:date>
  <dc:description>&lt;p&gt;Recognition of differences in the habitats, apparatuses, and ranges of Late Devonian&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;Icriodus&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;and&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;Pelekysgnathus&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;permits refinement of their biofacies interpretations and construction of an alternate icriodontid zonation.&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;Icriodus&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;is a euphotic genus that predominated in most environments during the early Late Devonian (Frasnian) but died out during the early Famennian. Its apparatus consists of platform (I) elements; four larger, acodiniform cones; and two smaller, oneotodiform, scolopodiform, or drepanodiform cones.&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;Pelekysgnathus&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;is a shallow-water genus, which shortly after&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;Icriodus&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;died out, produced somewhat deeper water taxa with triple-rowed I elements that are homeomorphs of&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;Icriodus&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;I elements. Apparatuses for both single-rowed taxa (&lt;i&gt;Pelekysgnathus&lt;/i&gt;) and triple-rowed taxa (&lt;i&gt;“Icriodus”)&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;contain oistodiform cones, apparently in place of one or more of the acodiniform cones. Biofacies models for southern Belgium and Utah show that&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;Icriodus&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;lived not only in nearshore environments but ranged into the pelagic palmatolepid-bispathodid (I) and palmatolepid-polygnathid (II) biofacies. Younger&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;“Icriodus”,&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;however, inhabited mainly the deeper subtidal polygnathid-“icriodid” (III) and polygnathid-pelekysgnathid (IV) biofacies.&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;Pelekysgnathus&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;inhabited mainly the polygnathid-pelekysgnathid biofacies and ranged shoreward into the shallow-subtidal clydagnathid (V), scaphignathid (VI), patrognathid (VII), and pandorinellinid (VIII) biofacies, but has not yet been found in the hypersaline antognathid (IX) biofacies (new).&lt;/p&gt;&lt;p&gt;The Late Devonian, subdivided by 28 mainly&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;Palmatolepis&lt;/i&gt;-based zones from the Lower&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;(Polygnathus) asymmetricus&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;to Upper&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;(Siphonodella) praesulcata&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;Zones in the standard conodont zonation for pelagic biofacies, can be subdivided into nine icriodontid-based zones in nearshore biofacies. In ascending order, these are the&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;Icriodus symmetricus;&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;Lower and Upper&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;Pelekysgnathus planus;&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;Lower, Middle, and Upper “&lt;i&gt;I&lt;/i&gt;.”&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;cornutus&lt;/i&gt;; and Lower, Middle, and Upper “&lt;i&gt;I&lt;/i&gt;.”&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;costatus&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;Zones. Taxonomic revisions involve mainly relegating several previously described species to subspecies and morphotypes and raising some subspecies to species. Two new biostratigraphically significant subspecies,&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;I. iowaensis ancylus&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;n. subsp. and&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;I. alternatus helmsi&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;n. subsp., are recognized to occur both in the western United States and in Europe.&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;Pelekysgnathus brevis&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;n. sp. is described as new on the basis of a Middle Devonian occurrence in Utah.&lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1130/SPE196-p143</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>GSA</dc:publisher>
  <dc:title>Late Devonian icriodontid biofacies models and alternate shallow-water conodont zonation</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>