Quiz #2 Potential Questions

Short Answer:

1. Compare the two schools of biological classification (traditional taxonomy, cladistics) 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. For two of these techniques, describe the results of a paleontological study which used that technique (you can describe one study that used 2 techniques, or two studies that each used one technique.
3. Two possible uses of long sauropod necks have been suggested: underwater grazing or treetop browsing. Describe at least two lines of evidence that support or challenge each of these hypotheses.
4. What causes variations in salinity, temperature, and oxygen content of ocean water? How do each of these factors affect organisms? How do water depth and substrate affect organisms?
5. How have each of the following biological processes affected marine organisms in the geologic past: predation, competition, symbiosis? Include examples of each process from the fossil record.
6. 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.
7. List at least three aspects of ancient environments that can be recognized using carbon isotope ratios. For each explain how and why the ratios are distinctive.
8. Describe three different sources of variation within a population and give an example of how to recognize each one in fossil organisms.
9. Why do most organisms exhibit anisometric growth?
10. 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
11. Explain how I could use oxygen isotopes to recognize each of the following. Be sure to explain why O-18 would be enriched or depleted in each case.:

• organisms from freshwater v marine environments
• carbonate rocks formed during a glaciation
• carbonates formed in equatorial areas

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 two] basic approaches to taxonomy, I prefer the evolutionary (traditional taxonomy) 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 traditional 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. Dinosaurs have been found in Alaska, which was at pretty high latitudes during the Mesozoic. This discovery has some implications for the biology and ecology of these organisms. 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 but complete about what kind of information can be determined from each element (carbon or oxygen). Only discuss uses of isotopes that are relevant to this specific problem.