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<p>clock be <a href="page.php?w=calibration">calibrated</a> using independent evidence about dates, such as the <a href="page.php?w=fossil">fossil</a> record. There are two general methods for calibrating the molecular clock using fossils: node calibration and tip calibration.</p>

<p><big>Node calibration</big></p>
<p>Sometimes referred to as node dating, node calibration is a method for time-scaling <a href="page.php?w=phylogenetic_tree">phylogenetic tree</a>s by specifying time constraints for one or more nodes in the tree. Early methods of clock calibration</p><p>
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