| A | B |
|---|
| fossil | preserved remains or traces of living things |
| petrified | turned into stone |
| extinct | an organism no longer exists and would never live again on Earth |
| paleontologist | a scientist who studies fossils |
| evolution | the gradual change of living things over long periods of time |
| cast | a solid copy of the shape of an organism |
| sedimentary rock | a type of rock made from hardened sediment |
| sediment | material removed by erosion |
| mold | a hollow area or cavity in sediment in the shape of an organism or part of the organism |
| petrified fossils | fossils in which minerals replace all or part of organism |
| carbon film | an extremely thin coating formed when some of the materials in an organism evaporate or become gases |
| trace fossil | a preservation of an organism’s activity |
| scientific theory | a well-tested concept that explains a wide range of observations |
| preserved fossil | forms when entire organisms or parts of organisms are prevented from decaying by being trapped in rock, ice, tar, or amber |
| carbon | a common element in all living things |
