Index Fossil (Noun)
Meaning
A fossil known to have lived in a particular geologic age that can be used to date the rock layer in which it is found.
Classification
Nouns denoting natural objects (not man-made).
Examples
- Trilobites are often used as index fossils to date the rock layers of the Paleozoic Era.
- The discovery of the ammonite index fossil in the rock layer helped geologists determine its age.
- Index fossils like brachiopods are essential in correlating rock layers across different regions.
- The presence of the graptolite index fossil in the shale layer indicated that it was from the Ordovician Period.
- By identifying the index fossil of a specific species of coral, scientists were able to date the limestone rock layer.