PLEISTOCENE ICE AGES AND MAMMAL MEGAFAUNA EXTINCTION

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 Paintings

Answer 2

(35-10 kyr B.P.) provide vista onto Pleistocene Mammal Fauna
Paintings show mammoths with shaggy hair
(Wholly rhinos?)

Question 3

Glacial-Interglacial shifts in plant biomes

Answer 3

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

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

American lion & cheetah, sabertooth cat, dire wolf, short-faced bears

Question 6

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

Answer 6

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

Question 7

Quaternary (end-Pleistocene) MegaFauna Extinction

Answer 7

only land mammals
“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

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

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

Pygmy Mammoths (last ones died ~6 kyr after end-Pleistocene Megafauna Extinction)44
Pygmy Mammoths lived on Wrangel Island when Egyptians were building pyramids