Palaeontology

Palaeontology is a branch of geology focused on the study of remnants of ancient live forms preserved in rocks.
Palaeontologists typically use secondary electron (SE) observation to reveal the morphology of fossils. Secondary electrons are formed very close to the sample surface, have a high spatial resolution and reveal very fine details of the sample surface. They also have a larger depth of focus than light microscopy. Electron microscopes are capable of resolving details at the sub nanometre range compared to hundreds of nanometres in optical systems. Higher depth of focus is needed for imaging large three dimensional complex shaped fossils and fossil remnants.
  • Electron microscopy is typically used in palaeontology for the identification and taxonomy on microfossils. A conductive coating is usually applied to discharge the electron beam current.
  • Microfossils are generally smaller than a few millimetres. The most common organisms are algae, protozoa, and crustaceans. Large populations of microorganisms occurred over a very wide geographical area. Their wide distribution and relative sensitivity to environmental changes have made microfossils into so-called index fossils that are used in the dating of sedimentary sequences.
  • Macrofossils can also be studied because of the high depth of focus. Similarly, the bones of small vertebrates can also be studied to determine the causes of different surface marks.
  • Specimens which cannot be coated by a conductive layer can be observed under the low vacuum conditions preventing the accumulation of charge.
  • A special SE detector was developed for this purpose – LVSTD (Low Vacuum Secondary Electron TESCAN Detector).
Palaeontology
Dynoflagelata