Pleistocene Ice Ages and Mammal Mega-Fauna Flashcards
When was “Last Glacial Maximum” (LGM)?
- started 25 kyr and ended 11 kyr ago
Mastodon Teeth vs. Mammoth Teeth
Mastodon: more jagged like (for browsing)
Mammoth: look a lot like modern elephant teeth (stacked for grazing)
Ice Age Carnivores of North America
American Lion, and American cheetah, Sabertooth Cat, Dire Wolf, Short-Faced Bears
La Brea Tar Pits
- California
- predators remains greatly outnumber number of prey remains
Quartnernary (end-Pleistocene) Mega-Fauna Extinction
- affected only those above 44 Kg. (and only land mammals)
- affected all continents but at different times
- dated at about 11 kyr B.P. (end-Pleistocene) in North America
Evidence Supporting Overkill Hypothesis
For: timing of extinctions occurred relative to the arrival of humans in North America
For: evidence of mega-fauna being hunted
For: mega-fauna tend to take longer to raise children making it easier for generations to go extinct
Evidence Against Overkill Hypothesis
Against: Mega-fauna in Australia went extinct long before humans arrive
Against: Bison were hunted too, how are they still around today?
Against: extinctions happened in North America before Bearing Land Bridge
What are corollaries to large body size in mammals and why might this make them susceptible to extinction?
- greater individual longevity
- longer pregnancies (like miserably long, poor them)
- longer time to reach sexual maturity
- birth fewer offspring
- not as many individual mega-fauna to keep up with hunting humans
Wrangel Island Refugium
- place of the last mammoths (Pygmy Mammoths)
- died ~6 kyr after End-Pleistocene Megafauna Extinction