PLEISTOCENE ICE AGES AND MAMMAL MEGAFAUNA EXTINCTION (5/2)

Question 1

When was “Last Glacial Maximum” (LGM)?

Answer 1

○ Started 25 kyr ago and ended 11 kyr ago

Question 2

European Stone Carvings & Cave Painting

Answer 2

• European Stone Carvings & Cave Paintings (35-10 kyr B.P.) provide vista onto Pleistocene Mammal Fauna
○ Paintings show mammoths with shaggy hair

Question 3

Glacial-Interglacial shifts in plant biomes

Answer 3

• Glacial-Interglacial shifts in plant biomes
○ Tundras, boreal-spruce forests, and pinewood hard forests were found further down south in North America compared to today

Question 4

Mastodon Teeth vs. Mammoth Teeth

Answer 4

• Mastodon Teeth vs. Mammoth Teeth
○ Mammoth teeth are similar to the teeth of modern elephants (more washboard-like)
○ Mastodons are diverged from mammoths a pretty long time ago; their teeth are more tooth-like

Question 5

Ice Age carnivores of North America:

Answer 5

• Ice Age carnivores of North America: American lion & cheetah, sabertooth cat, dire wolf, short-faced bears

Question 6

La Brea Tar Pits of California

Answer 6

• La Brea Tar Pits of California (11-50 kyr old)

○ “Predator trap”: predatory carnivores greatly outnumber herbivorous mammals 100’s of dire wolves

Question 7

Quaternary (end-Pleistocene) MegaFauna Extinction:

Answer 7

○ “Megafauna”: mammals weighing ≥44 kg (~100 lbs)
○ Affected all continents but at different times
○ Dated at about 11 kyr B.P. (end-Pleistocene) in North America
Clovis culture (excellent spear points) in North America dated at ~13 kyr

Question 8

Evidence for, and against, the Overkill Hypothesis

Answer 8

○ Evidence for, and against, the Overkill Hypothesis
§ For: timing of extinctions occurred relative to the arrival of humans in North America
§ For: evidence of megafauna being hunted
§ For: megafauna tend to take longer to raise children, thus making it easier for them to go extinct
§ Against: Megafauna in Australia went extinct long before humans arrived
§ Against: Bison were hunted too, so why are they still around today?
§ Against: extinctions happened in north america before Bering Land bridge

Question 9

What are corollaries to large body size in mammals and why might this make them susceptible to extinction?

Answer 9

• What are corollaries to large body size in mammals and why might this make them susceptible to extinction?
○ Greater individual longevity
○ Longer pregnancies
○ Longer time to reach sexual maturity
○ Birth fewer offspring
○ Not as many individual megafauna to keep up with hunting humans

Question 10

Wrangel Island Refugium:

Answer 10

• Wrangel Island Refugium: Pygmy Mammoths (last ones died ~6 kyr after end-Pleistocene Megafauna Extinction)

Question 11

Pygmy Mammoths

Answer 11

• Pygmy Mammoths lived on Wrangel Island when Egyptians were building pyramids