Data from: The role of inhibitory dynamics in the loss and re-emergence of macropodoid tooth traits

The reversibility of phenotypic evolution is likely to be strongly
influenced by the ability of underlying developmental systems to generate
ancestral traits. However, few studies have quantitatively linked these
developmental dynamics to traits which re-evolve. In this study we assess
how changes in the inhibitory cascade, a developmental system that
regulates relative tooth size in mammals, influenced the loss and
reversals of the posthypocristid, a molar tooth crest, in the kangaroo
superfamily Macropodoidea. We find that posthypocristid loss is linked
with reduced levels of posterior molar inhibition, potentially driven by
selection for lophodont, higher-crowned molar teeth. There is strong
support for two posthypocristid reversals, each occurring after more than
15 million years of absence, in large-bodied species of Macropus, and two
giant extinct species of short-faced sthenurine kangaroo (Procoptodon). We
find that whereas primitive posthypocristid expression is linked to higher
levels of posterior molar inhibition, re-emergence is tied to a relative
increase in third molar size associated with increasing body mass,
producing molar phenotypes similar to those in mouse where the
ectodysplasin pathway is up-regulated. We argue that although shifts in
the inhibitory cascade may enable re-emergence, dietary ecology may limit
the frequency of phylogenetic reversal.