Micropaleontology
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Micropaleontology, the study of microfossils, is a branch of paleontology. Microfossils are fossils generally smaller than 1 mm, whose study requires the use of light microscopy or scanning electron microscopy. Fossils which can be studied with the naked eye, or low-powered magnification are referred to as macrofossils.
Microfossils are a common feature of the geological record, from the Precambrian to the Quaternary, and are found in most marine and terrestrial sediments. While every Kingdom of life is represented in the microfossil record, the most abundant forms are protist skeletons or cysts from the phyla Chrysophyta, Pyrrhophyta, Sarcodina, acritarchs and chitinozoans together with pollen and spores from vascular plants.
Micropaleontology is traditionally divided into three areas of study on the basis of microfossil composition, which can be calcereous, siliceous, or organic. This division reflects differences in the laboratory processing and preparation of sediment and rock samples rather than any taxanomic or ecological distinctions.
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Calcareous microfossils
Calcareous microfossils include Coccoliths, Foraminifera, Calcareous dinoflagellates, Ostracods, and Conodonts.
Siliceous microfossils
Siliceous microfossils include Diatoms, Radiolaria, and Silicoflagellates.
Organic microfossils
The study of organic microfossils is called palynology. Organic microfossils include pollen, spores, Chitinozoans, Scolecodonts, Acritarchs, Dinoflagellate cysts, and fungal remains.
Methods
Sediment or rock samples are collected from either cores or outcrops, and the microfossils they contain extracted by a variety of physical and chemical laboratory techniques, including sieving, density separation by centrifuge, and chemical digestion of the unwanted fraction. The resulting concentrated sample of microfossils is then mounted on a slide for analysis, usually by light microscope. Taxa are then identified and counted. The large numbers of microfossils that a small sediment sample can often yield allows the collection of statistically robust datasets which can be subjected to multivariate analysis.
Applications of Micropaleontology
Micropaleontology has proved an excellent tool for sedimentary rock-body dating and for paleoenvironmental reconstruction, heavily used by petroleum geology, it has also found a number of more non-orthodox applications, such as its growing role in forensic police investigation.
References
- Brasier, M.D. (1980), Microfossils. Chapman and Hall publishers. ISBN 0412445700
- Traverse, A. (1988), Paleopalynology. Unwin Hyman ISBN 0045610010
External links
- The Micropalaeontological Society (http://www.nhm.ac.uk/hosted_sites/tms/)
- Centre for Palynology, University of Sheffield, UK (http://www.shef.ac.uk/uni/academic/N-Q/palysc/index.html)
- The American Association of Stratigraphic Palynologists (AASP) (http://www.palynology.org/)
- Commission Internationale de Microflore du Paléozoique (CIMP) (http://www.shef.ac.uk/~cidmdp/), international commission for Palaeozoic palynology.
- CIMP Subcommission on Acritarchs (http://www.shef.ac.uk/~cidmdp/cimpsuba.html)
- CIMP Chitinozoan Subcommission (http://www.shef.ac.uk/~cidmdp/cimpsubc.html)
- Micropaleontology Press, a division of the Micropaleontology Project, a nonprofit organization with the mission of promoting the science of micropaleontology. (http://micropress.org/)
- University of California, Berkeley, microfossil collections. (http://www.ucmp.berkeley.edu/collections/microhold.html)
- The Ocean Drilling Programme (ODP) Micropaleontological reference centres. (http://www-odp.tamu.edu/mrc/mrcpage.HTML)
- University College, London, Micropalaeontology Unit, including the MIRACLE microfossil image database. (http://www.ucl.ac.uk/GeolSci/micropal/)