1. Why Study Paleoecology?
-- how and why communities change
-- causes of extinctions, development of
modern communities
-- predict future changes

2. Grand Canyon, AZ

3. Fossil remains mummify and preserve quite well in dry caves

4. California Condor once nested in Grand Canyon caves

5. Gymnogyps californianus
Radiocarbon date of 12,540 B.P.
Gymnogyps californianus
(California Condor)

6. Condors have been
successfully reintroduced to
Grand Canyon, nesting again
for first time in 10,000 yrs

7. Problems with fossil record
-- Preservation varies
soft parts usually don’t preserve
exceptions in ice, bogs, amber
-- Mode of deposition important
stream deposits accumulate fossils
caves preserve cave-dwelling species
natural traps
-- Behavior of species important
caves and natural traps again

8. Taphonomy: Uniformitarianism:
-- understanding the history of deposition
Uniformitarianism:
-- physical processes of today (weathering,
stream flow, erosion) are the same as
in the past

9. Giant Armadillo

10. Fossil Assemblages can be:
-- Biocoenose: represent a true community
from the past
-- Thanatocoenose: not a true community,
but an assembly of species associated
only in death, or only in fossil deposit
What would be the ideal fossil site?

11. Bushy-tailed Woodrat

12. woodrat midden

13. The Last Glacial Maximum (LGM) at ~18,000 B.P.
jan.ucc.nau.edu

14. Changes in pinyon tree distribution since the Ice Ages

16. Disharmonius
or Non-analog
Faunas

17. Mixed or non-analog plant and animal communities
characterize the late Pleistocene in North America
Species assemblages with no modern analogy, usually
composed of taxa that occur in warm and cold climates
that are not found together today
e.g., lemmings in cave faunas in the western U.S. along
with desert rodents, or snowy and hawk owls with
vultures and sage grouse
This pattern was probably due to mild winters and cool
summers that characterized post-LGM climates

18. Loss of megafauna and keystone species would
have had a dramatic impact on plant and small
mammal communities
By the end of the Pleistocene at 10,000 B.P., over 30 genera
of large mammals became extinct
Small mammals (< 5 kg), however, suffered few or no extinctions
Modern communities were well established by 6000 B.P.

19. Cement Creek Cave, Colorado (elev. 2950 m or 9500 feet)

20. All sediments were screen washed,
dried, and sorted for bone

21. Thousands of small mammal bone
fragments and teeth, especially
from voles and other rodents,
have been recovered.
Possibly due to use of cave by
weasels; numerous weasel bones
in fossil assemblage.

22. Shrub-ox (Euceratherium collinum)
wickipedia.com
Euceratherium
Shrub-ox (Euceratherium collinum)
Browser that fed primarily on trees and shrubs,
especially sagebrush, rabbitbrush, acacia, oak
(Kropf et al. 2007) 22

23. Sagebrush Vole (Lemmiscus curtatus)
thehandfordproject.com
Lemmiscus
Sagebrush Vole (Lemmiscus curtatus)
Primarily feeds on flowers, bark, twigs of sagebrush, plus
lots of grasses, forbs, and woody plants (Fitzgerald et al. 1994) 23

24. Current sagebrush habitat near
Gunnison, with dense stands of
sagebrush and grasses
Modern steppe has more grasses,
forbs, especially bunch grasses
mixed in with sagebrush

25. Rancho la Brea Tar Pits, CA
George C. Page Museum

27. Dire Wolf skulls

29. Paleobiology of
Sabretooth cat based
on functional morphology

32. What happened 10,000 years ago? -- mass extinctions worldwide
-- targeted mainly large mammals
-- 33 genera of ‘megafauna’ disappear
-- marine life, plants largely unaffected
Pleistocene Overkill Hypothesis
-- proposed by Paul Martin in 1960s
-- extinctions correlated with human
population expansion
-- hunted large mammals, arrived in NA
at ~12,500 years ago
-- testable, controversial hypothesis that
is still valid

33. Names to know for final exam: know their major contributions
to ecology, significance of their work.
Robert MacArthur
Charles Krebs
Jane Lubchenco
Joseph Connell
G. F. Gause
Margaret Davis
Paul Martin
C. H. Merriam
Paul Ehrlich