Data from: Spatiotemporal sampling patterns in the 230 million year fossil record of terrestrial crocodylomorphs and their impact on diversity

The 24 extant crocodylian species are the remnants of a once much more
diverse and widespread clade. Crocodylomorpha has an approximately 230
million year evolutionary history, punctuated by a series of radiations
and extinctions. However, the group's fossil record is biased.
Previous studies have reconstructed temporal patterns in subsampled
crocodylomorph palaeobiodiversity, but have not explicitly examined
variation in spatial sampling, nor the quality of this record. We compiled
a dataset of all taxonomically diagnosable non‐marine crocodylomorph
species (393). Based on the number of phylogenetic characters that can be
scored for all published fossils of each species, we calculated a
completeness value for each taxon. Mean average species completeness (56%)
is largely consistent within subgroups and for different body size
classes, suggesting no significant biases across the crocodylomorph tree.
In general, average completeness values are highest in the Mesozoic, with
an overall trend of decreasing completeness through time. Many extant taxa
are identified in the fossil record from very incomplete remains, but this
might be because their provenance closely matches the species’ present‐day
distribution, rather than through autapomorphies. Our understanding of
nearly all crocodylomorph macroevolutionary ‘events’ is essentially driven
by regional patterns, with no global sampling signal. Palaeotropical
sampling is especially poor for most of the group's history.
Spatiotemporal sampling bias impedes our understanding of several Mesozoic
radiations, whereas molecular divergence times for Crocodylia are
generally in close agreement with the fossil record. However, the latter
might merely be fortuitous, i.e. divergences happened to occur during our
ephemeral spatiotemporal sampling windows.