class="cn">NULL</span>,</span>
<span>  taxa <span class="op">=</span> <span class="cn">NULL</span>,</span>
<span>  missing_taxa <span class="op">=</span> <span class="cn">NULL</span>,</span>
<span>  ncalibration <span class="op">=</span> <span class="cn">NULL</span>,</span>
<span>  age_distribution <span class="op">=</span> <span class="st">"fixed"</span>,</span>
<span>  root_calibration <span class="op">=</span> <span class="cn">FALSE</span>,</span>
<span>  mrbayes_constraints_file <span class="op">=</span