LingakuAlsoしじゅんかせき
- index fossil; zone fossil; guide fossil; indicator fossilgeology and paleontology
noun (common) (futsuumeishi)
Generated: This term refers to fossils used by paleontologists to define and identify particular time periods in the geological time scale. They are distinctive, abundant, and short-lived species that help in correlating the ages of rock layers.
Ammonites are very important as index fossils of the Mesozoic era.