The preservation potential of terrestrial biogeographic patterns

Extinction events in the geological past are similar to the present-day
biodiversity crisis in that they have a pronounced biogeography, producing
dramatic changes in the spatial distributions of species. Reconstructing
paleobiogeographic patterns from fossils therefore allows us to examine
the long-term processes governing the formation of regional biotas, and
potentially helps build spatially-explicit models for future biodiversity
loss in a potential ‘6th mass extinction’ event. However, the extent to
which biogeographic patterns can be preserved in the fossil record is not
well understood. Here, we perform a suite of simulations based on the
present-day distribution of North American mammals, aimed at quantifying
the preservation potential of beta diversity and spatial richness patterns
over extinction events of varying intensities, and after applying a
stepped series of taphonomic filters. We show that taphonomic biases
related to body size are the biggest barrier to reconstructing
biogeographic patterns over extinction events, but that these may be
compensated for by both the small-mammal record preserved in bird
castings, as well as range-expansion in surviving species. Overall our
results suggest that the preservation potential of biogeographic patterns
is surprisingly high, and thus that the fossil record represents an
invaluable dataset recording the changing spatial distribution of biota
over key intervals in Earth History.