Chapter 09 Author: Lee Hannah

FIGURE 9.1 Timeline of Extinction Events. Major extinctions are indicated by yellow bars. Along with climate change, impacts and volcanic episodes are leading possible causes of major extinction spasms. Reproduced with permission from Christopher R. Scotese.

FIGURE 9.2 Major and Minor Extinctions. Diversity of genera over 500 million years. (A) The red plot shows the number of known marine animal genera versus time. (B) The black plot shows the same data, with single occurrence and poorly dated genera removed. The trend line (green) is a third-order polynomial fitted to the data. (C) Same as B, with the trend subtracted and a 62-Myr sine wave superimposed. (D) The detrended data after subtraction of the 62-Myr cycle and with a 140-Myr sine wave superimposed. Dashed vertical lines indicate the times of the five major extinctions. From Rohde, R. A. and Muller, R. A Cycles in fossil diversity. Nature 434, 208 – 210. CH009.

FIGURE 9.3 Marine Benthic Habitats Before and After the Permian-Triassic Extinction Event. A marine fauna of 100 or more species is reduced to less than 6 species based on seabed reconstructions off south China. From Benton, M. J., and Twitchett, R. J How to kill (almost) all life: The end-Permian extinction event. Trends in Ecology & Evolution 18, 358– 365.

FIGURE 9.4 End-Eocene Global Cooling. The initiation of the first permanent Antarctic ice sheets in the past 100 million years coincided with end-Eocene cooling, indicated by an arrow at approximately 34 mya. Reproduced with permission from Yale University Press.

FIGURE 9.5 Methane Outgassing. Methane trapped in sediments as clathrate may be released in periods of warming. Outgassing from sediments in the Santa Barbara channel during interglacials is illustrated in this drawing. Release of methane from clathrates has also been implicated in rapid warming at the Paleocene – Eocene thermal maximum. Reproduced with permission from AAAS.

FIGURE 9.6 Species Lost at End-Pleistocene. Some of the dozens of species lost in North and South America at the end of the Pleistocene are illustrated, including saber-tooth cats (Smilodon) and wooly mammoth ( Mammuthus primigenius ). From Wikimedia Commons.

FIGURE 9.7 Declining Mammoth Range. Modeled loss of mammoth range due to human expansion (dark line) and climate change (color ramp; red most suitable), from 126,000 years ago to the end of the Pleistocene. From Nogues- Bravo, D., et al Climate change, humans, and the extinction of the woolly mammoth. PLoS Biology 6, 685 – 692.