Bio1151 Chapter 25 The History of Life on Earth
  1. A major tool biologists use to study early life on earth is the fossil record buried in layers of                rock.

  2. The 4.6 billion years of earth's history is divided into three geologic        , which are further divided into         and           .

  3. Early photosynthetic                released oxygen, allowing the evolution of              .

  4. The first eukaryotes probably evolved from                  of prokaryotes within larger host cells and developing into organelles.

  5. Most of the major animal phyla appeared during the early             period in what is known as the             Explosion.

  6. Mammals are synapsids that belong to the group of chordates called             .

  7. The movement of the Earth's               due to continental          has shaped the diversity of life on Earth.

  8. There have been several episodes of mass               , though the trend has been an             in diversity over time.

    • The               (KT) extinction is famous for the disappearance of              (except birds).

  9. The extinction of the dinosaurs may have led to the             radiation of other species, such as mammals, which diversified to adapt to new           now made available.

    A Scrolling Geologic Record: