Differential Preservation of Marine Environments and Biased Diversity Trends: Modeling Effects and Empirical Validation

How well do observed patterns in fossil diversity reflect the original trends? This question has troubled paleobiologists for decades and has inspired a flurry of recent research. Clearly the amount of rock preserved at any given time will determine the number of fossil taxa recovered, but the picture is much more complicated. During changes in sea level, certain environments are preserved better than others. Since actual diversity varies among environments as well, any differential preservation of environments will bias preserved diversity trends. We offer a model to explore the possibility of a preservation bias in observed diversity trends. Within a framework of an onshore-offshore gradient with multiple environments, gradients of diversity, extinction, and preservation are applied to produce a degraded diversity record. The interactions of these three gradients can produce diversity, origination, and extinction trends which mimic those seen in the fossil record. While preservation cannot fully explain all variations in the fossil record, the model suggests that preservation may be partly responsible, and in some cases play a significant role. We use some empirical data for each of the three gradients to validate the model and compare synthetic data to actual data.