Pleistocene (2.58–0.01 Ma)

Recent Ice Ages; Death of Mega-fauna
The Pleistocene Epoch is in the Quaternary Period of the Cenozoic Era. It occurs before the Holocene, and after the Pliocene Epoch.

What happened during this time?
  • Geologic
    • The severe climatic changes during the ice age had major impacts on the fauna and flora. 
      • With each advance of the ice, large areas of the continents became totally depopulated, and plants and animals retreating southward in front of the advancing glacier faced tremendous stress. 
      • There has not been and ice-free period in the Arctic Ocean for 2.6 million years (although that may be quickly changing)
  • Biologic
    • The most severe stress resulted from drastic climatic changes, reduced living space, and curtailed food supply
      • Extinction event of mega-fauna took place between 13.8–11.4 Ka (Faith 2013)
        • Quick disappearance seems to indicate a sudden catatrophic event such as human over-hunting or cosmic impact
    • Origin of the genus Homo around 2.4–2.3 Ma
      • Evidence that early hominids fed on underground storage organs (such as tubers), sedges, fruits, leaves, and bark, as well as invertebrates, honey, and vertebrate animals, whether scavenged or hunted (K. Sayers, Georgia State University)
      • Opportunistic foraging was probably optimal for early hominids diets.
      • Evidence of agriculture in present-day Israel from 23,000 year ago (Snir et al. 2015)
        • 140 plant species present, including wild oat, barley, and emmer wheat along with 13 weed species that are common today.
    • Pleistocene Arc Hypothesis: "Present-day, disjunct, fragments of dry forests in central tropical South America give evidence of a previously more continuous distribution during the Pleistocene that has been disrupted by dry-cold vs. humid-warm climatic cycles" (Mogni et al. 2015)
    • Probable origin of "Pando", a vast group of quaking aspens (Populus tremuloides) and the Earth's largest and probably oldest organism
      • The group of trees grow in Fishlake National Forest, east of Salt Lake City, UT
      • The organisms comprises about 47,000 tree trunks, all connected underground as root offshoots, making this one large cloned organism.
      • Researchers have estimated that Pando originated between 80,000 to one million years ago.
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