How are index fossils used to identify the subdivisions of the geologic time scale?
- ?Lv 71 month ago
Evolutionary paleontologists use ‘index fossils’ to assign an age to a layer of sedimentary rock and its associated fossils.
Evolutionary theory assumes that a particular creature evolved from its ancestors, lived successfully for a period, then became extinct as its descendants evolved better ways of surviving. In other words, that creature had a defined ‘evolutionary life-span’.
However these assumptions are dubious. Even index fossils are often found out of place and the assigned evolutionary age ranges keep growing.Source(s): https://creation.com/index-fossils