Quiz #2 Potential Questions

Short Answer:

1. Compare the three schools of biological classification (traditional taxonomy, cladistics, phenetics) based on goals, methods, use of characters, and areas of objectivity/subjectivity.
2. Paleontologists use four basic techniques to investigate the function of structures in fossils: analogy to living organisms, analyzing the biomechanics of the organism, building physical models, building mathematical models. Describe the results of a paleontological study which utilized at least two of these techniques.
3. Describe three different sources of variation within a population and give an example of how to recognize each one in fossil organisms.
4. What causes variations in salinity, temperature, and oxygen content of ocean water? How do these factors and water depth and substrate affect organisms?
5. Contrast these environments with respect to physical limiting factors (salinity, temperature, oxygen, depth and substrate): rocky intertidal, muddy intertidal, sandy subtidal.
6. How have each of the following biological processes affected marine organisms in the geologic past: predation, competition? Include examples of each process from the fossil record.
7. Explain each of these modes of growth and describe how that growth mode affects information about the organism that can be deduced from the fossil record.
   • accretion
   • addition
   • molting
   • modification
8. Why do most organisms exhibit anisometric growth?
9. List at least four aspects of ancient environments that can be recognized using oxygen isotope ratios. For each explain how and why the ratios are distinctive.
10. List at least four aspects of ancient environments that can be recognized using carbon isotope ratios. For each explain how and why the ratios are distinctive.

Essays

1. Debate over cladistic classification is particularly bitter among paleontologists working on ancient reptiles, dinosaurs and birds. Here is a statement from the Web page of an evolutionary biologist:

Of [the three] basic approaches to taxonomy, I prefer the evolutionary approach. The reasons for this are summarized as follows:

1. The information content is higher.
2. It promotes greater stability.
3. It enhances ease of use.
4. It results in a more balanced classification.

Discuss this statement first from the viewpoint of an evolutionary taxonomist, then from a cladistic viewpoint. Use the example of the classification of reptiles, birds and mammals to argue each side. Be sure you address each of the points listed above for each of the classification systems.

2. Reefs represent a critical intersection of the biosphere with the solid earth where organisms directly shape geological environments. Describe the general structure of reefs and the subenvironments created within that structure. Include a discussion of how limiting factors vary between reef subenvironments, and what adaptations organisms have developed in response to those limiting factors. How have reefs changed over geologic time?

3. Dinosaurs have been found in Alaska, which was at pretty high latitudes during the Mesozoic. This discovery has some implications for the debate over whether dinos were warm-blooded. Suppose you are the paleobiogeochemist (how's that for a job title?) in charge of investigating a duck-billed dinosaur skeleton recovered from Alaska. What information could you extract from this skeleton by analyzing oxygen and carbon isotope ratios? Be specific about what kind of information can be determined from which element (carbon or oxygen). Only discuss uses of isotopes that are relevant to this specific problem.

4. Describe how carbon and oxygen stable isotope ratios vary between and within marine and terrestrial environments. Use diagrams to illustrate your answer. What kinds of information can you determine from oxygen isotopes? from carbon isotopes?