How are index fossils used to identify the subdivisions of the geologic time scale?

1 Answer

  • ?
    Lv 7
    1 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. 

Still have questions? Get your answers by asking now.