Data from: Fossilisation can mislead analyses of phenotypic disparity

Analyses of morphological disparity can incorporate living and fossil taxa
to facilitate the exploration of how phenotypic variation changes through
time. However, taphonomic processes introduce non-random patterns of data
loss in fossil data and their impact on perceptions of disparity is
unclear. To address this, we characterise how measures of disparity change
when simulated and empirical data are degraded through random and
structured data loss. We demonstrate that both types of data loss can
distort the disparity of clades, and that the magnitude and direction of
these changes varies between the most commonly employed distance metrics
and disparity indices. The inclusion of extant taxa and exceptionally
preserved fossils mitigates these distortions and clarifies the full
extent of the data lost, most of which would otherwise go uncharacterised.
This facilitates the use of ancestral state estimation and evolutionary
simulations to further control for the effects of data loss. Where the
addition of such reference taxa is not possible, we urge caution in the
extrapolation of general patterns in disparity from datasets that
characterise subsets of phenotype, which may represent no more than the
traits that they sample.