Among the most intriguing and significant aspects of the marine stratigraphic record are patterns of temporal change in fossil assemblages and paleocommunities. Understanding the stratigraphic patterns and the correct temporal scale of such faunal change is crucial to interpreting the underlying processes involved. Inattention to the temporal scale at which paleontological data are collected, and at which faunal change is observed, often results in the use of entirely inappropriate explanatory models. In many cases modern ecological theories have been misapplied to the fossil record because problems of scale were not adequately considered. The term “community” itself has been applied to such a wide range of fossil accumulations that it has ceased to have any consistent paleoecologic meaning (see discussion in Järvinen et al.,1986). For this reason, we prefer to use the term “assemblage” for time-averaged accumulations of fossils, and restrict “community” to only those organisms which actually lived together in the same space and time (i.e., a biocoenosis). Therefore, faunal assemblages, even when untransported, are the preserved amalgamated record of many successive communities within which short-term (10 – 100 years) changes may or may not be resolvable. Recurrent, compositionally similar assemblages, believed to have occupied generally similar benthic environments, are then grouped into biofacies which can be seen to intergrade and migrate through time.
Defining the niche for niche construction: evolutionary and ecological niches
