| A | B |
|---|
| paleontologist | a scientist who studies fossils |
| fossil | remains, imprints, or traces of prehistoric organisms that can tell when and where organisms once lived and how they lived |
| permineralized remains | fossils in which the spaces inside are filled with minerals from ground water |
| carbon film | thin film of carbon residue preserved as a fossil |
| mold | a type of body fossil that forms when an organism with hard parts is buried, decays or dissolves and leaves a cavity in the rock |
| cast | a type of body fossil that forms when crystals fill a mold or sediments wash into a mold and harden into a rock |
| index fossil | remains of species that existed on Earth for a relatively short period of time, were abundant, and were widespread geographically, and can be used by geologists to assign the ages of rock layers |
| original remains | amber surrounds and protects the original material of the insect's exoskeleton from destruction |
| trace fossils | fossilized tracks and other evidence of the activity of organisms |
| trails & burrows | can tell something about how animals lived |
| sedimentary rock | rock formed when sediments are cemented and compacted or when minerals are precipitated from solution |
| principle of superposition | states that in undistrubed rock layers, the oldest rocks are on the bottom and the rocks become progressively younger toward the top |
| relative age | the age of something compared with other things |
| unconformity | gap in the rock layer that is due to erosion or periods without any disposition |
