l divergence time estimates are based 
 solely on the <a href="javascript:TextPopup(this)" id="HotSpot50573" class="glossterm" style="font-family: Arial, sans-serif; 
 font-size: 12pt;">branch</a><script type="text/javascript">//<![CDATA[
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//]]></script><span class="glosstext" id="POPUP50573" style="display: none;"> A branch is a line connecting either two internal nodes to each other or an external node to an internal node in a phylogenetic tree.  The length of a