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PALEOECOLOGY AND PALEOCLIMATES 113

2 Modern populations can show a variety
of different size distributions. Fossil assem-
50 dead blages can also show size–frequency pat-
Temperature (˚C) 40 live terns. What sorts of processes can modify

the original population polygons of a
30
once-living species?
20
10 3 Paleocommunities through time increased
their diversity by the expansion of eco-
space. Why then did diversity reach a
2.3 2.1 1.9 1.7 1.5
plateau during the Paleozoic but appears to
(a) still be increasing in the Modern fauna?
4 Large-scale ecological changes seem to be
decoupled from major changes in taxo-
oxygen nomic diversity. Is this a valid observation
1000
Gases (ppm) 100 CO 2 or are our data too crude to actually test
this?

methane 5 The Earth has suffered huge extremes in
10 climate through time. Can the Gaia
hypothesis help explain these climate
swings? Will the planet ever experience a
(b)
real snowball Earth?

0.8 photosynthesizers
Population 0.6 consumers Bennett, K.D. 1997. Evolution and Ecology: The Pace
Further reading

0.4
of Life. Cambridge University Press, Cambridge, UK.
(Relationship between ecology and evolution from a
0.2 methanogens
Quaternary perspective.)
Brenchley, P.J. & Harper, D.A.T. 1998. Palaeoecology:
Time before present (Ma) Ecosystems, Environments and Evolution. Rout-
(c) ledge. (Readable textbook on most aspects of current
paleoecology.)
Figure 4.28 Precambrian Gaia and evolution of Briggs, D.E.G. & Crowther, P.R. (eds) 1990. Palaeobiol-
the biosphere. (a) Changes in climate in a live ogy – A Synthesis. Blackwell Scientifi c Publications,
and lifeless world; there is a sharp fall in Oxford. (Modern synthesis of many aspects of con-
temperature when oxygen appears. (b) The temporary paleontology.)
changing abundance in atmospheric gases. (c) Copper, P. 1988. Paleoecology: paleoecosystems, paleo-
Changes in the composition of ecosystems: both communities. Geoscience Canada 15, 199–208.
the photosynthesizers and methanogens increase (Concise but informative integration of the main
concepts of paleocommunity ecology.)
initially when oxygen appears but the
Cronin, T.M. 1999. Principles of Paleoclimatology. Per-
methanogens eventually decline to a much lower
spectives in Paleobiology and Earth History. Colum-
level of abundance. (Population is the proportion
bia University Press, New York.
of the total population in tenths.) (From
Frakes, L.A., Francis, J.E. & Syktus, J.I. 1992. Climate
Lovelock 1998.) Modes of the Phanerozoic. Cambridge University
Press, Cambridge, UK. (Overview of ancient climates
through time.)
Review questions Lovelock, J. 1998. The Ages of Gaia. Bantam Books,
1 Living communities contain a very wide New York. (Stimulating discussion of the Gaia
variety of lifestyles. Although dominated hypothesis.)
by members of the Modern fauna, ele- Vermeij, G.J. 1987. Evolution and Escalation. An Eco-
logical History of Life. Princeton University Press,
ments of the Paleozoic (suspension- Princeton, NJ. (Fundamental text on the infl uence of
feeding) fauna are still present. Is it predation on the history of life.)
possible to predict the sorts of habitats Vrba, E.S. 1996. Climate, heterochrony, and human
that they prefer? evolution. Journal of Anthropological Research 52,