<?xml version='1.0' encoding='utf-8'?>
<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:creator>John A. Barron</dc:creator>
  <dc:date>2003</dc:date>
  <dc:description>&lt;p&gt;&lt;span&gt;Recently published&amp;nbsp;&lt;/span&gt;diatom&lt;span&gt;&amp;nbsp;biochronologies provide accurate (to 0.1&amp;nbsp;&lt;/span&gt;m&lt;span&gt;.&lt;/span&gt;y&lt;span&gt;.) determination of the ages of&amp;nbsp;&lt;/span&gt;appearances&lt;span&gt;&amp;nbsp;and disappearances of&amp;nbsp;&lt;/span&gt;planktonic&lt;span&gt;&amp;nbsp;diatoms during the&amp;nbsp;&lt;/span&gt;past&lt;span&gt;&amp;nbsp;&lt;/span&gt;18&lt;span&gt;&amp;nbsp;&lt;/span&gt;m&lt;span&gt;.&lt;/span&gt;y&lt;span&gt;.&amp;nbsp;&lt;/span&gt;in&lt;span&gt;&amp;nbsp;the equatorial&amp;nbsp;&lt;/span&gt;Pacific&lt;span&gt;, North&amp;nbsp;&lt;/span&gt;Pacific&lt;span&gt;, and&amp;nbsp;&lt;/span&gt;Southern&lt;span&gt;&amp;nbsp;&lt;/span&gt;Ocean&lt;span&gt;. Comparisons of these records reveal the age of evolutionary&amp;nbsp;&lt;/span&gt;appearance&lt;span&gt;&amp;nbsp;and&amp;nbsp;&lt;/span&gt;extinction&lt;span&gt;&amp;nbsp;of species and their region of origin. Extinct&amp;nbsp;&lt;/span&gt;planktonic&lt;span&gt;&amp;nbsp;&lt;/span&gt;diatom&lt;span&gt;&amp;nbsp;species have a mean longevity of 3.4 ± 2.8&amp;nbsp;&lt;/span&gt;m&lt;span&gt;.&lt;/span&gt;y&lt;span&gt;. (SD, n = 53)&amp;nbsp;&lt;/span&gt;in&lt;span&gt;&amp;nbsp;the equatorial&amp;nbsp;&lt;/span&gt;Pacific&lt;span&gt;, 2.5 ± 2.1&amp;nbsp;&lt;/span&gt;m&lt;span&gt;.&lt;/span&gt;y&lt;span&gt;. (n = 52)&amp;nbsp;&lt;/span&gt;in&lt;span&gt;&amp;nbsp;the North&amp;nbsp;&lt;/span&gt;Pacific&lt;span&gt;, and 2.9 ± 2.3&amp;nbsp;&lt;/span&gt;m&lt;span&gt;.&lt;/span&gt;y&lt;span&gt;. (n = 38)&amp;nbsp;&lt;/span&gt;in&lt;span&gt;&amp;nbsp;the&amp;nbsp;&lt;/span&gt;Southern&lt;span&gt;&amp;nbsp;&lt;/span&gt;Ocean&lt;span&gt;. The relatively large standard deviations are likely due to the inclusion of taxa that probably could be subdivided into two or more species.&amp;nbsp;&lt;/span&gt;In&lt;span&gt;&amp;nbsp;the equatorial&amp;nbsp;&lt;/span&gt;Pacific&lt;span&gt;, evolutionary turnover of&amp;nbsp;&lt;/span&gt;diatom&lt;span&gt;&amp;nbsp;species was relatively high between&amp;nbsp;&lt;/span&gt;18&lt;span&gt;.0 and 6.0 Ma compared with the period after 6.0 Ma, presumably reflecting changing oceanic circulation and evolving water masses.&amp;nbsp;&lt;/span&gt;In&lt;span&gt;&amp;nbsp;the North&amp;nbsp;&lt;/span&gt;Pacific&lt;span&gt;, evolutionary turnover speaked between 10.0 and 4.5 Ma, with increasing high-latitude cooling and enhanced provincialism.&amp;nbsp;&lt;/span&gt;In&lt;span&gt;&amp;nbsp;the&amp;nbsp;&lt;/span&gt;Southern&lt;span&gt;&amp;nbsp;&lt;/span&gt;Ocean&lt;span&gt;, evolutionary turnover of endemic diatoms was greatest between 5.0 and 1.6 Ma, which provides evidence for the strong provincial character of Pliocene&amp;nbsp;&lt;/span&gt;diatom&lt;span&gt;&amp;nbsp;assemblages. Taken as a whole, oceanic&amp;nbsp;&lt;/span&gt;diatom&lt;span&gt;&amp;nbsp;assemblages became increasingly provincial&amp;nbsp;&lt;/span&gt;in&lt;span&gt;&amp;nbsp;character during the late Miocene and Pliocene, as pole-to-equator thermal gradients increased and oceanic frontal systems were strengthened.&lt;/span&gt;&lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1080/0269249X.2003.9705588</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>Taylor &amp; Francis</dc:publisher>
  <dc:title>Planktonic marine diatom record of the past 18 m.y.: Appearances and extinctions in the pacific and southern oceans</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>