Bio1152 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 called         .

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

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

  4. Mammals are synapsids that belong to the group of vertebrates called            .

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

  6. There have been several episodes of mass              , but the extinct forms were replaced by others that evolved from the survivors; the trend has been an           of diversity over time.

    • The          (PT) extinction was the most severe, and claimed over 90% of marine species.

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

  7. 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.
Bio1152 Chapter 26 Phylogeny and The Tree of Life
  1.            is the study of the evolutionary history and relationships of organisms, based on shared          characters inherited from a common           .

  2. Carolus Linnaeus introduced a system of           , for classifying species in seven hierarchical categories (taxa).

  3. Phylogenetic relationships are shown as branching trees where each branch point represents the             of two       when they shared a common           (homology).

    •                similarity can be misleading due to             evolution (analogy).

    •            homologies that make use of computer programs to analyze      segments can reveal many relationships not attainable by other methods.

  4. Shared ancestry and shared          characters are drawn on a            to show evolutionary relationships; this practice is called             .

  5. A clade must be               , and consists of the           species and all its descendants;

  6. The tree of life is divided into three great clades called          :           (Monera),          , and          .