Applied Biostratigraphy

Many geologists use terms like “biostratigraphy”, “micropaleontology”, “microfossils”, “nannofossils” etc. freely and interchangeably. This is understandable, but has lead to confusion in the past especially between terms Micropaleontologist and Nannopaleontologist – and the “wrong kind” of biostratigrapher being requested for a particular job. Even for actual practitioners, the term “micropaleontology” can cover numerous meanings. Here are a few informal definitions…

Stratigraphy: The way sedimentary rocks are named, ordered, classified and correlated on earth. (~pher: a person who engages in such study).

Biostratigraphy: The study of the use of fossils (of any size) as a tool in stratigraphy. (Biostratigrapher: a person who engages in such study).

Micropaleontology (1-formal): The study of any fossils which are small enough to require a microscope to observe them. (~ist: a person who engages in such study). Microfossils is, strictly speaking, the term used to define all such small fossils but is more commonly used as described below.

Micropaleontology (2-common): The study of certain different groups of small, mineralised fossils, usually those which range in size between 0.063mm up to 1-2mm in size, occasionally larger. These can include foraminifera, ostracods, radiolaria, diatoms, conodonts and others. A binocular, incident-light microscope capable of magnifications between 50x – 500x is normally used although occasionally transmitted light is needed for thin-section analysis. (~ist: a person who engages in such study). Microfossils is the term commonly used to collectively describe the various groups of fossils included here.

Nannopaleontology: The study of a certain group of (very) small, mineralised fossils, usually those which range in size between approximately 0.005 – 0.030mm (“nannometric” size). This group includes primarily the calcareous nannoplankton which comprises coccoliths and discoasters. A binocular, transmitted-light microscope capable of magnifications between 500x – 2000x is used. (~ist: a person who engages in such study). Nannofossils is the term commonly used to collectively describe the various groups of fossils included here.

Palynology: The study of certain groups of (very) small fossils with organic walls, usually those which range in size between approximately 0.005 – 0.030mm (“nannometric” size). These can include dinoflagellates, acritarchs and spores & pollen. A binocular, transmitted-light microscope capable of magnifications between 500x – 2000x is used. (~ist: a person who engages in such study). Palynomorphs is the term commonly used to collectively describe the various groups of fossils included here.

The authors prefer to use the terms underlined above (“Microfossils”, “Nannofossils” and “Palynomorphs”) for the various different fossil groups in question and to use the collective term “Biostratigrapher” to describe the people who carry out the studies and “Biostratigraphy” to describe the practice as a whole.

Note that words like paleontology and micropaleontology can be spelt with an additional “a” (palaeontology) which is a British language characteristic. Although the authors are themselves British the more “international” variations are used in this manual.