What are microfossils?
There is no difference between microfossils and macrofossils, other than size. If you need a microscope to see it properly, it is a microfossil.
Microfossils can be used to correlate rocks. They can be found in the chippings produced when drilling boreholes and these contain thousands of undamaged microfossils. Some rocks such as chalk or chert are composed almost entirely or microfossil remains. Their preservation in ocean floor sediments makes them ideal for investigating evolutionary theory.
These are complex crustaceans, related to crabs and trilobites. They have two valves, a hinge with teeth and sockets and adducter muscles to close them, which is similar to bivalves. They are usually less than 2mm in length. The shell or carapace is made of chitin or calcium carbonate.
Osracods range from Cambrian to the present day, although the earliest groups are now extinct. They have a long stratigraphic range and mainly a benthonic mode of life, which means they are poor zone fossils. They are superb paleo - environmental indicators, having different forms in waters of the entire range of salinity.T