Data from: Phylogenetic stability, tree shape, and character compatibility: a case study using early tetrapods

Phylogenetic tree shape varies as the evolutionary processes affecting a
clade change over time. In this study, we examined an empirical phylogeny
of fossil tetrapods during several time intervals, and studied how
temporal constraints manifested in patterns of tree imbalance and
character change. The results indicate that the impact of temporal
constraints on tree shape is minimal and highlights the stability through
time of the reference tetrapod phylogeny. Unexpected values of imbalance
for Mississippian and Pennsylvanian time slices strongly support the
hypothesis that the Carboniferous was a period of explosive tetrapod
radiation. Several significant diversification shifts take place in the
Mississippian and underpin increased terrestrialization among the earliest
limbed vertebrates. Character incompatibility is relatively high at the
beginning of tetrapod history, but quickly decreases to a relatively
stable lower level, relative to a null distribution based on constant
rates of character change. This implies that basal tetrapods had high, but
declining, rates of homoplasy early in their evolutionary history,
although the origin of Lissamphibia is an exception to this trend. The
time slice approach is a powerful method of phylogenetic analysis and a
useful tool for assessing the impact of combining extinct and extant taxa
in phylogenetic analyses of large and speciose clades.