Data from: The mosasaur fossil record through the lens of fossil completeness

The quality of the fossil record affects our understanding of
macroevolutionary patterns. Palaeodiversity is filtered through geological
and human processes; efforts to correct for these biases are part of a
debate concerning the role of sampling proxies and standardization in
biodiversity models. We analyse the fossil record of mosasaurs in terms of
fossil completeness as a measure of fossil quality, using three novel,
correlating metrics of fossil completeness and 4083 specimens. A new
qualitative measure of character completeness (QCM) correlates with the
phylogenetic character completeness metric. Mean completeness by species
decreases with specimen count; average completeness by substage varies
significantly. Mean specimen completeness is higher for species‐named
fossils than those identified to genus and family. We consider the effect
of tooth‐only specimens. Importantly, we find that completeness of species
does not correlate with completeness of specimens. Completeness varies by
palaeogeography: North American specimens show higher completeness than
those from Eurasia and Gondwana. These metrics can be used to identify
exceptional preservation; specimen completeness varies significantly by
both formation and lithology. The Belgian Ciply Formation displays the
highest completeness; clay lithologies show higher completeness values.
Neither species diversity nor sea level correlates significantly with
fossil completeness. A generalized least squares (GLS) analysis using
multiple variables agrees with this result, but reveals two variables with
significant predictive value for modelling averaged diversity: sea level,
and mosasaur and plesiosaur‐bearing formations (the latter is redundant
with diversity). Mosasaur completeness is not driven by sea level, nor
does completeness limit the mosasaur diversity signal.