Data from: Bayesian tip dating reveals heterogeneous morphological clocks in Mesozoic birds

Recently, comprehensive morphological datasets including nearly all the
well-recognized Mesozoic birds became available, making it feasible for
statistically rigorous methods to unveil finer evolutionary patterns
during early avian evolution. Here, we exploited the advantage of Bayesian
tip dating under relaxed morphological clocks to estimate both the
divergence times and evolutionary rates while accounting for their
uncertainties. We further subdivided the characters into six body regions
(i.e., skull, axial skeleton, pectoral girdle and sternum, forelimb,
pelvic girdle, and hindlimb) to assess evolutionary rate heterogeneity
both along the lineages and across partitions. We observed extremely high
rates of morphological character changes during early avian evolution and
the clock rates are quite heterogeneous among the six regions. The branch
subtending Pygostylia shows extremely high rate in the axial skeleton,
while the branches subtending Ornithothoraces and Enantiornithes show
notably high rates in the pectoral girdle and sternum, and moderately high
rates in the forelimb. The extensive modifications in these body regions
largely correspond to refinement of the flight capability. This study
reveals the power and flexibility of Bayesian tip dating implemented in
MrBayes to investigate evolutionary dynamics in deep time.