What can we learn from the geological and fossil record about the evolution of eukaryotes and metazoans?
Though we can extrapolate back from existing organisms or build theoretical biogeochemical models, the only robust empirical data that shows how early life on Earth evolved and interacted with its environment comes from the study of early Precambrian rocks. Despite popular misconceptions, globally there is in fact a moderate abundance of well-preserved Archaean (>2.5 Ga) and Palaeoproterozoic (2.5-1.6 Ga) rocks, which can serve as our clearest windows on the events that occurred shortly after life’s origin. Further research was performed in 2003 on Archean hydrocarbon biomarker geochemistry, sulfur isotopic fractionation, and Paleoproterozoic hydrocarbon preservation in fluid inclusions. Also, new research was initiated in the areas of metamorphism of Archean biosignatures, Archean paleobarometry, and on the age and origin of controversial “microfossils” putatively of Archean age from the Pilbara Craton, Australia. Field-work was conducted on Hadean supracrustal rocks from Isua, Greenl
