Reading Assignment 61.What was Darwin’s view of mass extinctions? How did that fit in with his overall view of evolution? How did the Signor-Lipps effect explain Darwin’s data in exactly the opposite manner?Darwin’s view of mass extinctions is that they occur gradually and are not sudden; in other words, mass extinctions take places over generations as species disappear little by little. Mass extinctions are spread out in time and less extreme instead of being short in duration and catastrophic. He rejected the idea that organisms became extinct through brief catastrophes. This fits in with his overall view of evolution in that changes occur over time (natural selection) and are not sudden. The Signor-Lipps effect explained Darwin’s data in the opposite manner by describing that if sudden extinction events occurred, gradualism would still be present; the rarer species would die first and then the more common fossils would persist until the upper boundary. Therefore, a graded series of fossil disappearances might indicate a sudden wipeout.
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