Taphonomic megabiases constrain phylogenetic information in the squamate fossil record

Fossil data is subject to inherent biological, geological, and
anthropogenic filters that can distort our interpretations of ancient life
and environments. The inevitable presence of incomplete fossils thus
requires a holistic assessment of how to navigate the downstream effects
of bias on our ability to accurately reconstruct aspects of biology in
deep time. In particular, we must assess how biases affect our capacity to
infer evolutionary relationships, which are essential to analyses of
diversification, paleobiogeography, and biostratigraphy in Earth history.
In this study, we use an established completeness metric to quantify the
effects of taphonomic filters on the amount of phylogenetic information
available in the fossil record of 795 extinct squamate (e.g., lizards,
snakes, amphisbaenians, and mosasaurs) species spanning 242 million years
of geologic time. This study found no meaningful relationship between
spatiotemporal sampling intensity and fossil record completeness. Instead,
major differences in squamate fossil record completeness stem from a
combination of anatomy/body-size and affinities of different squamate
groups to specific lithologies and depositional environments. These
results reveal that naturally occurring processes create structural
megabiases that filter anatomical and phylogenetic data in the squamate
fossil record, while anthropogenic processes play a secondary role.