1. Humans and the Pleistocene Megafaunal Extinction
Kelsey T. Stilson

2. Cultural and Climate Revolution
Migrations change both humans and the ecosystem.
Shared Space
Humans
Ecosystem
Climate
Novel System

3. Stepped Global Extinction Events
Barnosky, AD; Koch, PL; Feranec, RS; Wing, SL; Shabel, AB. Assessing the causes of late Pleistocene extinctions on the continents. Science (New York, N.Y.) 2004 Oct 1; 306(5693): 70-5.

4. North America
Exceptions = mesofauna (such as some species of rodent and rabbit) that also went extinct. Many species also didn’t die out, but went through a genetic bottleneck (grey wolves)
Emphasize that this is not a “tragedy” but a fundamentally different ecology that went through a radical change.
American Horse, Mammoths, Mastodons, Lions, Cheetahs, Giant Ground Sloths, Camels, Glyptodonts, Indricotheres, Saber-toothed cat, Dire wolves, Peccaries, Tapirs…
Exceptions

5. Why do we look at Megafauna?
Megafauna = 44+ kg (100 lbs)
Early indicators of climate change! =
Megafauna are important because the occupy a somewhat precarious niche space. They are large herbivores that are fewer in number, have a slow reproduction rate, and require lots of calories to survive, making them the preeminent taxa to become extinct in an ecosystem. Like the canary in a coal mine, megafauna act as an early warning system for

6. ANTARCTIC REGLACIATION MEGAFAUNAL EXTINCTION
Cenozoic
ANTARCTIC GLACIATION
ANTARCTIC REGLACIATION
MEGAFAUNAL EXTINCTION
THERMAL MAXIMUM
ANTARCTIC
THAWING
65 Ma 58 37 24 5 2
11,500 yrs
Paleocene
Eocene
Oligocene
Miocene
Pliocene
Pleistocene
Holocene

7. Human Influence 16 Ka
Overkill (Blitzkreig) Hypothesis: Paleoindians hunted the megafauna to extinction (Paul Martin)
Timing is right, but the evidence is limited for complete human responsibility.
Too few taxa Few kill sites
‘Sitzkrieg’ Hypothesis: other ways humans alter the environment (Jared Diamond) Ka

8. Other Predators Non- human Predators
Human Predation
Non-human predators forced to hunt less calorically efficient prey
Prey population controlled by predators
Abundant resources and habitat space
Non- human Predators
Prey population numbers controlled by Predators
Abundant resources and habitat space

9. Hyperdisease
Brought over by humans or dogs with the migration over beringia.
Extremely deadly
This would require the virus or bacteria to ‘jump’ between different Orders, something that has never been observed in modern biology.

10. Bolide Impact

11. Guthrie, Dale R. New carbon dates link climatic change with human colonization and Pleistocene extinctions. Nature Vo Issue 7090 p.207

12. Implications for the Future
Overkill, Over-chill, Over-ill…
Humans today affect the ecosystem, how far back does this go?
Depends on culture
How will we change as we
change our environment?

13. Thank You!
Special thanks to Professor Mark Carey, Professor Sam Hopkins, and Dr. Edward Davis