Chapter 7 - Extinction

Notes for Evolution - The Triumph of an Idea - Chapter 7

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or back to Chapter 6 or ahead to Chapter 8

General guide on these review questions here

Chapter 7 - Extinction - How Life Begins Again

PBS Website Link

Objectives:

a) Contrast Darwin's gradualistic pattern of extinctions with the current understanding of extinction episodes.

b) Consider competing hypotheses that might individually or together explain the most dramatic extinction events.

c) Draw generalities about typical patterns of recovery following a mass extinction event.

d) Become familiar with the evidence that humans have historically been responsible for species extinctions.

e) Contrast pessimistic and optimistic views of the future of biodiversity on a planet increasingly populated by humans.

Introduction

Links on Mass Extinctions: 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9

Featured Geologist: John Phillips (proposed three-part division of the geological record in 1841)
source of image

Links: 1 - 2 - 3

I. Introduction

RQ Ev-7.1: In retrospect, in what way was Darwin wrong about the pattern of extinctions in the fossil record?

II. The Great Curve

Featured Scientist: John Sepkoski
source of image

Links: 1 - 2 - 3 - 4

RQ Ev-7.2: Over the last 600 million years, when were the five most extensive major extinction events?

III. The Permian-Triassic Extinction: Brushing with Annihilation

See cool map of the Earth during the late Permian (255 MYA) here.

Did an asteroid impact cause this extinction event? Links: 1 - 2 - 3 - 4

Key Terms: synapsids (links: 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9)

RQ Ev-7.3: What are the primary hypotheses for explaining the Permo-Triassic extinction event and what evidence supports each?

Source of image

IV. Rebirth

Links: 1 - 2 - 3 - 4 - 5 - 6

RQ Ev-7.4: Describe the pattern of "rebirth" of land animals and plants following the Permo-Triassic extinction event.

V. Mammals: A Tiny Beginning

Links: 1 - 2 - 3 - 4 - 5 - 6

RQ Ev-7.5: What is the evidence that the early mammals were not superior to other land vertebrates? What ecological roles were they able to occupy during the Mesozoic Era?

VI. Death from Above

Visit the Source of this Page's Featured Image (© Douglas Henderson)
Representing the Long-lasting Late-Cretaceous Outpouring of Basalt in India
at Douglas Henderson's Earth History Illustrations Website

Links on the K/T Extinction event: 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - 10 - 11 - 12 - 13 - 14
Send a simulated asteroid at your favorite planet here

RQ Ev-7.6: Summarize the evidence that the K/T extinction event was primarily related to a massive asteroid (or comet) impact.

VII. Mammals Take the Field

RQ Ev-7.7: What was the pattern of land vertebrate recovery following the K/T extinction event?

VIII. Human Extinctions: The First Waves

Links: 1 - 2 - 3 - 4

RQ Ev-7.8: What evidence implicated humans in causing various recent extinction events, starting some 50,000 years ago?

IX. History in a Hole

RQ Ev-7.9: Summarize the pattern of extinction on the Hawaiian island of Kauai, based on studies by David Burney.

X. The Extinctions Accelerate

RQ Ev-7.10: Describe the relationship between extinction due to habitat fragmentation and the theory of island biogeography, as formulated by Robert MacArthur and E. O. Wilson (see p. 153-154).

XI. Alien Invasion

RQ Ev-7.11: What factors promote the often substantial success of "alien invader" species, and why are they considered among the most significant threats to the preservation of biodiversity?

XII. The Future of Extinctions

RQ Ev-7.12: What are the long-term implications of Stuart Pimm's finding that extinction patterns resemble that of radioactive decay?

XIII. Humanity Leaves its Mark

RQ Ev-7.13: What can humans do over the next century to lessen the extent of global extinctions?

Click link to return to Biology 409 Schedule
or back to Chapter 6 or ahead to Chapter 8