traditional fossils: replacement, permineralization , molds/casts, carbonization

trace fossils: tracks, burrows, coprolites, gastroliths

Fossil succession: age range, index fossils, short age range, easily recognized, widespread distribution; fossil assemblage

Describe the different ways in which fossils form. In which methods are original material preserved? Which are only traces left by the organism?

How are fossils used to determine the age of a rock? Why are index fossils particularly useful for dating rocks? Why is a fossil assemblage usually more helpful than a single fossil?

Fill in the blanks on a clad-o-gram