MACROSTRATIGRAPHY AND THE NORTH AMERICAN FOSSIL RECORD: ROCKS AND FOSSILS IN TIME AND SPACE

Spatially explicit paleontological databases that document fossil taxonomic occurrences, such as the Paleobiology Database (PaleoDB: http://paleodb.org), are enabling a new generation of macroevolutionary hypotheses to be rigorously tested. Here we combine a comprehensive macrostratigraphic database consisting of 22,520 surface and subsurface rock units at 803 locations in the United States and Canada with 28,163 fossil collections in the PaleoDB. Documenting the intersection of our knowledge of the fossil and rock records is the first step in 1) measuring the geological completeness of paleontological sampling, 2) overcoming geologically-mediated sampling biases, and 3) testing the extent to which spatio-temporal patterns in the sedimentary and fossil records are similarly structured by a shared set of forcing mechanisms, such as the expansion and contraction of shallow epicontinental seas. Preliminary results indicate that approximately 16% of all sedimentary rock units and 22% of all gap-bound sedimentary rock packages have at least one documented fossil occurrence in the PaleoDB. There is significant temporal asymmetry in this proportion, with Late Cretaceous and Cenozoic rock units having approximately 50% greater paleontological completeness, on average. The extent to which temporal asymmetry in the geological completeness of paleontological sampling has influenced long-term diversity estimates is explored.