Quantitative Analysis of Precambrian Fossils

As the Precambrian paleontological database continues to grow, it is now feasible to apply quantitative methods in the analysis of Precambrian fossils in order to characterize evolutionary patterns. Thus far, quantitative analysis of Precambrian fossils has been focused on taxonomic diversity, morphological characterization, and phylogenetic analysis. In this presentation, we will review several recent case studies of morphological characterization of Precambrian fossils, including acritarchs, macroalgae, and Ediacara fossils. Quantitative analysis of Precambrian acritarchs and benthic macroalgae suggests that their taxonomic diversity and morphological complexity increased markedly in the Ediacaran Period. Simple measurements such as surface/volume ratio can be used to indirectly infer paleoecology. For example, modeled surface/volume ratios of acritarchs and macroalgae can be used to estimate mass specific bioproductivity of primary producers. Similar methods have also been applied in the quantitative analysis of macroscopic Ediacara fossils. Preliminary results show that the morphological range of Ediacara fossils was maximized in the early Ediacara assemblage about 575-560 Ma, when taxonomic diversity was relatively low. Morphological range seems to have been constrained through the evolutionary history of Ediacara fossils, despite fluctuation in taxonomic diversity. This pattern appears to be similar to the morphological history of other eukaryotic groups.