Data from: Persistent body size bias in the fossil record of Cenozoic North American mammals

Body size is a key organismal trait with profound implications ranging
from individual physiology to large-scale macroecological or
macroevolutionary phenomena. Among extant terrestrial vertebrates, peak
diversity commonly occurs at small body size. Similarities between the
body size distributions of fossil and extant mammals have been used to
argue that fossil record signals are robust, yet preservation and
collector biases disproportionately favour the sampling of large taxa and
likely underrepresent small-sized diversity. Here, we quantify the effects
of these biases on the body size distributions of North American mammals
through the Cenozoic. We assess how these distributions have changed with
new palaeontological discoveries and evaluate sampling standardisation as
a potential correction for body size bias. Our results show bias in the
mammal record to be persistent and severe. Sampling standardisation has no
consistent effect on recovered distribution shape, likely because sample
coverage estimators cannot account for changes in the scope of the
sampling universe driven by a combination of historical worker interest
and the preservational characteristics of a small pool of formations.
Short of a novel standardisation method that can account for publication
biases, deriving non-artefactual fossil body size signals may ultimately
depend on targeted, systematic sampling of exceptional deposits.