Activities Key Terms Quizzes Art Chapter 22 Self-Quiz
Unit 4: Evolution The Evolutionary History of Life Review
  1. Life first evolved in the between 4 and 3.5 billion years ago when Earth had very low levels of atmospheric oxygen. Over time, the activity of photosynthetic in the period released oxygen into the atmosphere and set the stage for the emergence of , and eventually for multicellular organisms.
  2. The explosion marked a period of rapid growth in biological diversity including green algae. Most of the modern animal phyla and other groups now extinct appeared at this time, including the first .
  3. Descendants of multicellular were the first to colonize the land during the period.
  4. During the period, fish began to diversify, and invertebrate animals such as millipedes invaded land.
  5. During the period plants such as ferns diversified on land, and the first chordates to colonize land were which probably evolved from lobe-finned fish.
  6. During the period reptiles appeared and plants dominated land with innovations such as the for waterproofing, and for efficient transport and support in early Gymnosperms.
  7. During the period reptiles flourished due to the success of the egg which later led to the development of other animals. The supercontinent formed.
  8. During the period and early appeared.
  9. During the period dinosaurs diversified, and birds and appeared. Pangea began to break up.
  10. During the period Angiosperms diversified, and became extinct at the end of this period.
  11. Mammals started to dominate the terrestrial landscape during the period, and humans started to evolve during the period.
  12. At least five have occurred over the history of the Earth, with a sixth extinction possibly under way.
  13. The rapid diversification of a group of organisms is known as , which often occurs after mass extinction events. During the history of life, the has increased with time.
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