Research Interests

Using fossils and other geological and biological evidence, I study the history of life in the context of past environmental change. This work can be termed paleontology or paleobiology, but is best described as Geobiology. I am an evolutionary theorist but also conduct empirical research, uncovering and interpreting trends, rates, and patterns of evolution and extinction. To provide a framework, I delve into paleoceanography (the study of ancient oceans) and paleoclimatology (the study of ancient climates). Much of my early work was on the functional significance of shell form in bivalve mollusks and on the evolutionary history of this group. I have been especially concerned recently with the cause of the modern Ice Age and with the consequences of the ice age for all forms of life, including human ancestors. I have also related a global extinction of mammals about 7 million years ago to tooth abrasion caused by the sudden spread of silica-rich C4 grasses, and I have related changes in the dominant mineralogy of reef builders to changes in seawater chemistry governed by rates of spreading along mid-ocean ridges.

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Primary Section

Section 15: Geology

Secondary Section

Section 27: Evolutionary Biology