Microfossils as Proxies: Paleoecological and Paleoceanographic Indicators

Proxies are useful tools in paleoceanographic and paleoecological reconstructions. Biological proxies are represented by several groups of microfossils, some with calcareous walls like foraminifers, coccolithophorids, diatoms, bryozoans, micromollusks, ostracodes, and otoliths; and with silica walls, like radiolarians. These microfossils are remains of organisms of aquatic environments; when they died, they have been deposited in marine or lake sediments. Due to the mineral composition, they have a great chance of being preserved in the fossil record. Biological proxies are excellent paleoenvironmental indicators because their sensitivity to changes in environmental parameters such as temperature, pH, salinity, or changes in the concentration of toxic elements, which can cause the death of several individuals at the same time. This chapter describes the characteristics of biological proxies such as their habitat, ecology, distribution, and stratigraphic importance.