THE PRESERVATION OF MORPHOLOGICAL EVOLUTION IN A SEDIMENTARY BASIN: AN INVERSE APPROACH

The assumption that morphology and the temporal (i.e. stratigraphic) distribution of fossils are independent sources of data has supported conflicting arguments: to favor one type of data over the other, or to combine the two. Documenting species-level tempo and mode in the fossil record requires careful attention to the nature of the rock record that yields the morphological data. Previous studies have shown how stratigraphic architecture can influence patterns of taxonomic diversification, and at high resolution the dynamics and architecture of the sedimentary basin fill may affect stratophenetic patterns (i.e. perceived temporal morphological evolution). This exploratory study attempts to estimate parameters of a simple random walk model of anagenesis from a stratophenetic series, given stratigraphy and ecophenotypy. Simulation of morphological evolution ‘filtered’ through four (3rd order) depositional cycles is used to evaluate the statistical behavior of various estimators. The stratigraphic model gives sampling probability, size and distribution of unconformities and condensation, and a facies/environment history. Ecophenotypy determines the magnitude of the facies bias and the importance of parasequence stacking pattern (e.g. progradational vs. aggradational). Examples from the literature of species-level tempo and mode studies with sufficient stratigraphic information are discussed.