Name:_________________ Class:_________________
Directions: Answer the following questions as you navigate through Getting Into the Fossil Record.
1. What kinds of questions can the fossil record help us to answer?
Answers will vary. Some possibilities are: How did behaviors like flight evolve? What did the land look like in the past? What kind of organisms existed in the past? How did organisms move about?
2. Describe the difference between a body fossil and a trace fossil.
Body fossils are the fossilized remains of body parts such as leaves, teeth, skin or bones. A trace is any fossilized evidence of the organism EXCEPT the organism itself. Examples include burrows, footprints, nests or coprolites.
3. Why are organisms that are buried rapidly more likely to fossilize than those that are buried slowly or not at all?
Rapid burial protects an organism from biotic factors such as scavengers and decomposers, and from abiotic factors such as sun and wind, allowing the fossilization process to begin.
4. Describe two ways an organism can become a fossil without being buried in sediment.
Organisms can be preserved in tar, amber or ice.
5. How does the environment affect the formation of fossils?
Environments in which rapid and complete burial can occur quickly, such as the ocean floor or lake bottoms, are much more conducive to the formation of fossils. Environments in which dead organisms are readily broken down by biotic or abiotic factors, such as rain forests and rocky shorelines, prevent fossilization from occurring.
6. Describe three factors that could prevent an organism from long ago from ever turning up in a fossil collection today.
Not all organisms are equally protected from destruction after death, have structures which fossilize readily, or live and die in environments conducive to fossilization. Even if fossilization does occur, the fossil is subject to destructive geologic forces such as melting, crushing or erosion. And finally, most fossils remain hidden from us, buried deep inside the Earth.
7. How are geologic maps useful to paleontologists?
Geologic maps help paleontologists find rocks of the right age to search for answers to their questions.
8. In your own words, explain why the fossil record is not complete.
Only the remains of some organisms will die in an environment conducive to fossilization. Not all organisms resist destruction after death equally. Soft-bodied organisms are much more likely to decay than organisms with hard body parts such as bones, shells or teeth. Thus the fossil record contains many remains of creatures like fish, clams and mammals, and relatively few remains of creatures like jellyfish, earthworms or wild flowers.
BONUS: You have been hired by National Geographic Magazine to journey to Inner Mongolia in search of fossils. You have the good fortune to find a site filled with many fossilized leaves, teeth, bones, eggs and even footprints from a variety of creatures. Amidst this treasure trove of ancient life you find no trace of insects. Your research partner concludes that no insects lived here at that time. What other hypothesis might you suggest to your partner?
You must tell your partner that simply because one has not found evidence of insects, that in itself is not proof that they were not there at that time. This may have been an ancient environment with destructive forces that prevented insects from fossilizing. It is possible that geologic processes may have destroyed insect fossils in this area or you simply may not have found the insect fossils that are there.