The Ordovician zone index conodont &amp;lt;i&amp;gt;Amorphognathus ordovicicus&amp;lt;/i&amp;gt; Branson &amp;amp; Mehl, 1933 from its type locality and the evolution of the genus &amp;lt;i&amp;gt;Amorphognathus&amp;lt;/i&amp;gt; Branson &amp;amp; Mehl, 1933
Journal of micropalaeontology