Published online by Cambridge University Press: 21 July 2017
Generating and testing hypotheses is an integral part of any science, and some of the most stimulating paleobiological hypotheses of the past few decades relate to the ecological properties of fossils or fossil assemblages. Here, we outline recent methods for framing paleoecological questions that should facilitate the further quantitative evaluation of paleoecological hypotheses. First, we describe theoretical ecospaces, which are frameworks for classifying the ecologic properties of individuals or species based on multiple characters. We discuss the utility of theoretical ecospace in understanding evolutionary constraints and biodiversification, among other topics. Second, we discuss the reconstruction of high-resolution paleoecological gradients using ecological ordination techniques. Ordination can help uncover the paleoenvironmental factors that controlled fossil assemblage composition, track these factors through time, and evaluate the environmental and ecological context of major biotic changes. As an example, we present a new gradient analysis of the Yorktown Formation (Pliocene) of Virginia in which substrate and disturbance controlled molluscan assemblage composition. As a further example, we ordinate samples of mid-Paleozoic and late Cenozoic marine fossil assemblages based on their ecological content (as determined using a theoretical ecospace) to test whether the same environmental and ecological factors controlled the distribution of ecological lifestyles in both time intervals, despite the many differences between them. Although depth-related variation is evident in both data sets, the Cenozoic samples show stronger evidence of environmental control on ecologic content within depth zones. In contrast, Paleozoic gradients are consistent with a more random component in assemblage content. These analyses are quite preliminary, however, and should be verified with more extensive data.