Fossils

Organisms can also be preserved by mineralization (petrified),

►process in which minerals fill in pore spaces of an organism’s tissues.

When tree sap hardens, an insect may be preserved inside. 

Tahoma (Body)

►Any naturally preserved evidence of an animal’s activity is called a trace fossil.

►A mold is a cavity in the ground or rock where a plant or animal was buried.

►A cast is an object created when sediment fills a mold and becomes rock.

►Older rock layers contain organisms different from those found in younger rock layers.

►Life forms have changed over millions of years. For example, giant sea reptiles came before giant land dinosaurs. Mammals arrived last!