  The two major approaches to studying macroevolution in deep time are the
fossil record and reconstructed relationships among extant taxa from molecular
data. Results based on one approach sometimes conflict with those based on the
other, with inconsistencies often attributed to inherent flaws of one (or the
other) data source. What is unquestionable is that both the molecular and
fossil records are limited reflections of the same evolutionary history, and
any contradiction between them represents a failure of our existing models to
explain the patterns we observe. Fortunately, the different limitations of each
record provide an opportunity to test or calibrate the other, and new
methodological developments leverage both records simultaneously. However, we
must reckon with the distinct relationships between sampling and time in the
fossil record and molecular phylogenies. These differences impact our
recognition of baselines, and the analytical incorporation of age estimate
uncertainty. These differences in perspective also influence how different
practitioners view the past and evolutionary time itself, bearing important
implications for the generality of methodological advancements, and differences
in the philosophical approach to macroevolutionary theory across fields.
