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the fossil record
Holt earth science section 3
| Question | Answer |
|---|---|
| The remains or traces of animals or plants that lived in a previous geologic time are called | fossils |
| Why are fossils important? | they are an important source of information for finding the relative and absolute ages of rocks, clues to past geologic events, climates and evolution of living things over time. |
| The study of fossils is called | paleontology |
| Almost all fossils are found in what kind of rock? | sedimentary rock |
| Why are fossils found only in sedimentary rock? | The sediments that cover the fossils slow or stop the process of decay and protect the body of the dead organism from damage |
| Why are fossils rare in igneous rock or highly metamorphosed rock | because intense heat, pressure, and chemical reactions occur during the formation of this rock which destroys all organic structures. |
| Fossils give scientists what information about what 3 things? | 1. ages of rocks 2. changes in life forms 3. changes in the environment throughout time |
| The fossil record provides information about.... | the geologic history of Earth |
| How do fossils provide important clues to the environmental changes that occurred in Earth's past? | By revealing how organisms have changed through the geographical past |
| Give an example on how a fossil could tell us about changes of geography of earth | fossils of marine animals and plants that have been discovered far from ocean tells us that at one time that area was covered by an ocean |
| Normally dead plants and animals are decomposed by __________. | bacteria |
| How are some dead plants and animals preserved as fossils? | dead organisms that are buried quickly or protected from decay can become fossils. |
| Generally only what parts of an organism become fossils? | hard parts like wood, bones, shells, and teeth |
| True or False In some types of fossils only a replica of the original organism remains. | true |
| Fossils provide ________ that life once existed | evidence |
| List 5 ways in which fossils form | 1. mummification 2. amber 3. tar seeps 4. freezing 5. petrification |
| Mummified remains are often found in very ____ ________. | dry places |
| Why are mummified fossils not destroyed by bacteria? | because bacteria cannot survive in these places |
| How did some ancient civilizations mummify their dead | carefully extracted the body's internal organs and then wrapped the body in carefully prepared strips of cloth |
| What is amber? | Hardened tree sap |
| What types of fossils are typically found in amber? | insects because they get trapped in the sap and preserved when the sap hardens |
| In some rare cases even delicate features of insects such as _______ and _______ and even _____ have been preserved in amber. | legs and antennae and DNA (in rare cases) |
| What are tar seeps? | When thick petroleum oozes to Earth's surface, the petroleum forms a tar seep. |
| Tar seeps are commonly covered by what? | water |
| Why are fossils found in areas where there were tar seeps? | Animals come to drink water over the tar seep and get trapped. Even animals that feed on other trapped animals get trapped and leave fossils then both are covered again by tar and preserved |
| How do freezing conditions trap organisms and leave fossils? | low temperatures of frozen soil and ice prserve organisms because bacteria cannot survive in freezing temperatures and decay is prevented |
| What is petrification? | Minerals that precipitate from groundwater solutions replace original organic materials that have been buried under layers of sediment. |
| Name three common petrifying minerals | 1. silica 2. calcite 3. pyrite |
| In petrification the substitution of ______ for organic material often results in the formation of a nearly perfect mineral replica of the original organism | mineral |
| Name 4 types of fossils | 1. Carbon films 2. Molds and Casts 3. Coprolites 4. Gastroliths |
| What are Carbon film fossils? | When original organic material partially decays, it leaves behind a carbon-rich film that displays the surface features of the organism which is then preserved in sedimentary rock made of soft rock or clay. |
| Give some examples of the types of Carbon film fossils that have been found | Carbonized residues of leaves, stems, flowers, and fish |
| Shells often leave empty spaces called ______ within hardened sediment. | molds |
| When a shell is buried, its remains usually _____ and leave an empty space | dissolve |
| When sand or mud fills a ______ and turns into rock, a natural ______ forms. | mold; cast |
| (molds or cast) A ______ is a replica of the original organism. | cast |
| Poop can also be called? | dung or waste material |
| Fossilized dung or waste materials from ancient animals are called _________. | Coprolites |
| True or false Coprolites are fossils that can be cut into thin sections and observed through a microscope. | True |
| The material revealed in microscopic slices of Coprolite fossils can tell scientists what? | feeding habits of ancient animals, such as dinosaurs |
| True or False Some dinosaurs had stones in their digestive tracts to help grind their food. | True |
| Stones in the digestive tract of dinosaurs that helped them digest food are called? | Gastroliths (gastro means stomach and lith means stone)....stomach stones |
| Gastroliths can survive as fossils and are recognized by their what two things | smooth polished surface and close proximity to dinosaur remains |
| True or False fossils can show a remarkable amount of detail about ancient organisms. | true |
| True or False In some cases, no part of the original organism survives in fossil form. | True |
| a fossilized mark that formed in sedimentary rock by the movement of an animal on or within soft sediment is called | trace fossil |
| An example of a trace fossil is | footprints |
| Fossils that occur only in rock layers of a particular geologic age are called | index fossils |
| True or False To be considered an index fossil it must meet certain requirements. | True |
| What are the requirements for a fossil to be considered an index fossil? | 1. present in rocks scattered over a large region 2. have features that clearly distinguish it from other fossils 3. fossil formed must come from organism that lived during short span of geologic time 4. much occur in large numbers within the rock layers |
| Scientists can use _______ _________ to estimate absolute ages of specific rock layers. | index fossils |
| True or False Scientists can also use index fossils to date rock layers in separate areas. | True (and index fissil discovered in rock layers in different areas of the world indicates that the rock layers in these areas formed during the same time period |
| True or False Geologists use index fossils to help locate rock layers that are likely to contain oil and natural gas deposits. | true |
| Name 3 things geologists can discover using index fossils. | 1. estimate absolute ages of specific rock layers 2. date rock layers in separate areas 3. help locate rock layers that contain oil and natural gas deposits |
| How do oil and natural gas get deposited in rocks? | these deposits form from plant and animal remains that change by chemical processes over millions of years. |
| a fossil that is used to establish the age of rock layers because it is distinct, abundant, and widespread and existed for only a short span of geographical time | index fossil |
Created by:
kellyaem