Animals and Plants of Past and Their Records 619 

 QUESTIONS AND TOPICS 



1. Give your own definition of a fossil. 



2. Where have you found fossils, and what was their probable method of for- 

 mation? 



3. Of what importance in everyday life is a knowledge of animals and plants of 

 the past and their records? 



4. List several reasons why certain softer types of animals and plants have left 

 no fossil records. 



5. How are we able to estimate the age of the earth by a scientific study of the 

 fossils in the successive strata of the earth? 



6. Define index fossils and explain their values. 



7. Do geologic records reveal a progressive change in life in the past? Give 

 several specific examples from the animal and plant fields to prove or dis- 

 prove this statement. 



8. What conclusions do you draw from a careful study of the Geologic Time 

 Charts? Upon what evidence do you base these conclusions? 



9. If the older, earlier forms of life are found in the lower earth strata, and the 

 more recent life in the upper strata, what effects might glaciers, earthquakes, 

 and volcanic eruptions have on the proper interpretation of the data secured 

 from areas so affected? 



10. How have the various estimates of the age of the earth been made? How 

 accurate are these estimates? 



11. What is the estimated age of the earth from the Lower Precambrian Period 

 down to the present? 



12. What percentage of the total age of the earth represents the time which 

 human beings have inhabited the earth? 



13. As you remember specimens of petrified wood you may have seen, what were 

 its characteristics? Do these characteristics conform to those described in the 

 process of petrifaction? 



SELECTED REFERENCES 



Andrews: Ancient Plants and the World They Live In, Comstock PubHshing Co., 

 Inc. 



Arnold: An Introduction to Paleobotany, McGraw-Hill Book Co., Inc. 



Darrah: Textbook of Paleobotany, D. Appleton-Century Co., Inc. 



Eames: Morphology of Vascular Plants, McGraw-Hill Book Co., Inc. 



Huxley: Evolution, The Modern Synthesis, Harper & Brothers. 



Lucas: Animals of the Past, New York, American Museum of Natural History 

 (Handbook No. 4). 



Lull: Organic Evolution, The Macmillan Co. 



Raymond: Prehistoric Life, Harvard University Press. 



Schuchert and Dunbar: Textbook of Geology (part 2), John Wiley & Sons, Inc. 



Seward: Links With the Past in the Plant World, Cambridge University Press. 



Smith: Cryptogamic Botany (vol. 2): Bryophytes and Pteridophytes, McGraw- 

 Hill Book Co., Inc. 



Thomas: Paleobotany and the Origin of Aneriosperms, Botanical Rev^ 2: 397- 

 418, 1936. 



