Chapter Study Outline

  1. First True Mammals
    1. At the end of the Triassic period, therapsids, which were reptiles with mammalian
      1. traits, mostly disappeared.
      2. One lineage of therapsids evolved and diversified, becoming mammals.
      3. The Cenozoic era saw spectacular radiation of all the mammals, following extinction of the dinosaurs.
  2. Geology and Climate
    1. The earth's continents have moved significantly in the past 200 million years, from a large mass called Pangaea to the seven continents we recognize today.
    2. Continental drift affects evolution by putting up barriers that isolate species and by effecting climate change.
    3. The last 20 million years of climate change have dramatically altered the course of human evolution.
  3. Dating Fossils
    1. Deep sea cores.
    2. Radiometric methods: K-Ar, Carbon-14, thermoluminescence, electron-spin-resonance, U-Pb
    3. Relative dating methods: magnetic reversals, extinct and distinct species of animals
  4. Early Primate Evolution
    1. Plesiadapiforms
      1. Dated to the Paleocene, these shrewlike creatures were quadrupeds with a good sense of smell.
      2. Although they possess some primatelike traits, experts disagree as to whether or not plesiadapiforms should be considered part of the primate order.
    2. Primate traits
      1. Characteristic primate traits included binocular, stereoscopic vision, grasping hands and feet, and nails on the toes and fingers.
      2. Matt Cartmill—visual predation hypothesis
      3. Fred Szalay and Marian Dagosto—leaping locomotion hypothesis
      4. Robert Sussman and Tab Rasmussen—foraging hypotheses
    3. Eocene primates
      1. Omomyids were nocturnal with large eyes.
      2. Adapids were diurnal with smaller eyes.
      3. It is uncertain whether the anthropoids developed from the omomyids or
      4. the adapids.
  5. Haplorrhines Anthropoids
    1. Parapithecids
    2. Propliopithecids
    3. Oligopithecids
    4. New versus Old World monkeys
  6. Hominoids
    1. Radiated in the Oligocene.
    2. Emerged in the Miocene
    3. Proconsulids were quadrupedal and frugivorous but lacked tails like modern apes.
    4. About 157 mya, there emerged a number of hominoid species (such as Dryopithecus and Sivapithecus) throughout Europe, Asia, and Africa.
    5. In the late Miocene, a dry climate contributed to the extinction of numerous hominoids. All that remain are orangutans, gorillas, chimpanzees, and gibbons today.