| A | B |
|---|
| fossils | are the preserved remains or traces of living things |
| paleontologists | scientists who study fossils |
| sedimentary rock | the type of rock that is made of sediment |
| petrified fossils | fossils in which minerals replace all or part of an organism |
| mold | a hollow area in sediment in the shape of ancient organisms |
| cast | a copy of the shape of an organism |
| carbon film | an extremely thin coating of carbon on rock |
| trace fossil | provide evidence of the activities of ancient organisms |
| fossil record | provides evidence about the history of life on Earth |
| scientific theory | a well-tested concept that explains a wide range of observations |
| evolution | the gradual change in living things over long periods of time |
| extinct | a type of organism that no longer exists and will never again live on Earth |
