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End of Chapter 05 Questions

by Roger Bourke White Jr., copyright May 2018

Questions

1. Why is taxonomy important to interpreting the fossil record? What are some of the areas of confusion in applying the biological species concept to fossils? Explain how the paleospecies concept is used.

2. Remains of a fossil mammal have been found on your campus. If you adopt a cladistic approach, how would you determine (a) that it's a mammal rather than some other kind of vertebrate (discuss specific characters it possesses), (b) what kind of mammal it is (again, discuss specific characters), and (c) how it might be related to one or more living mammals (again, discuss specific characters)?

3. For the same fossil find (and your interpretation) in question 2, draw an interpretive figure using cladistic analysis (that is, draw a cladogram).

4. a. Humans are fairly generalized mammals. What do we mean by this, and what specific features (characters) would you select to illustrate this statement?
b. More precisely, humans are placental mammals. How do humans, and generally all other placental mammal, differ from the other two major groups of mammals?

Answers

1. We don't have DNA in fossils so we can't explore that to find out how one fossil relates to another. We are left with just looks -- taxonomy. We can guess about species, but these are just guesses, and, again, based on looks.

2. Using the cladistic approach one would check for distinctive mammalian characteristics in the fossil and its contemporary surroundings. For instance, those surrounding rocks could date the fossil. If the fossil has fur, a uterus or external male genitalia, then it is a mammal. Some bone structures are distinctly mammalian too.

3. Not going to bother with drawings in this discussion.

4. a. Except for our large brain, the rest of human body handles most day-to-day tasks in generalized ways. We don't have sharp teeth for catching running away prey, we don't run particularly fast, and we don't have lots of skin protection to fend off hostile elements such as cold temperatures.

b. Placental mammals raise their young for a long time in a mother's uterus. The young do a lot of developing in that environment. In humans this goes on for nine months. The converse is something like developing inside an egg, or inside a pouch.

 

 

--The End--

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