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massMass Extinctions and Their Aftermath

Adam D. Woods

Article number: 1.2.3R
1 August 1998

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A. Hallam, and P.B. Wignall, 1997
Oxford University Press
Walton Street
Oxford OX2 6DP, England
320 pages, softbound, $40.00; ISBN 0-19-854916-4.

One of the great driving forces of scientific research over the past two decades has been the study of mass extinctions. Mass extinction research is somewhat unique, in that it is greatly interdisciplinary in nature. Research has involved a wide variety of scientific disciplines both within and outside of the Earth sciences, including paleontology, geochemistry, paleoceanography, climate modeling, vulcanology, and astrophysics, to name a few. As a result of the broad scope of mass extinction research, most books on the subject have either concentrated on one of the "big five" mass extinctions (the end-Ordovician, the Late Devonian, the Permian-Triassic, the Triassic-Jurassic, or the Cretaceous-Tertiary mass extinctions), or provide only a cursory examination of each. Indeed, the "big five" mass extinctions are discussed in this book, and the authors provide a thorough discussion of each. In addition, one of the most pleasant surprises of the book is the inclusion of lesser known mass extinctions, including the Vendian mass extinction, the Late Cambrian biomere events, minor Jurassic mass extinctions, and the late Cenomanian extinction event, to name a few.

The first chapter provides a broad view of the various aspects associated with mass extinctions, beginning with an examination of how mass extinctions are defined, and the controversy that surrounds making such a claim. The authors then provide a brief history of the study of mass extinctions (beginning with Georges Cuvier), a discussion of the possibility of periodicity in mass extinctions, a review of the terminology of mass extinctions, an examination of the biological significance of mass extinctions, and end with a discussion of the various geochemical tools which have been used to attempt to determine the causes of mass extinctions. The first chapter contains a great deal of information, but given that the study of mass extinctions is highly interdisciplinary and covers a broad range of the Earth sciences and beyond, the wide scope of the first chapter is necessary.

The majority of the rest of the book is a chronological discussion of mass extinctions, starting with the Vendian mass extinction, and ending with the Pleistocene mass extinction. Each description of a particular mass extinction includes a review of what went extinct, the geochemical signatures around the event and their possible significance, a review of the possible causes of the mass extinction, and a discussion of the aftermath of the mass extinction, which concentrates primarily on biological trends, including faunal recovery following the mass extinction, and the overall effect the mass extinction had on Phanerozoic evolutionary patterns, if any. The discussion of what faunas went extinct at a particular event is particularly impressive, as the authors cover not only what specific taxa went extinct, but they also discuss how different life habits (e.g., epifaunal vs. infaunal) were affected by particular mass extinctions. In addition, relevant problems surrounding each mass extinction are also reviewed. For example, the authors provide a discussion of Upper Permian stratigraphy, as poor global correlation has led to much controversy over how gradual or sudden the Permian-Triassic mass extinction was.

The book concludes with a chapter on the causes of mass extinctions, where the authors review many of the commonly-cited kill mechanisms, and discuss the likelihood of each as a cause of mass extinctions. In general, the authors tend to favor anoxia associated with transgression as the primary causes of mass extinctions, however, they wisely point out that no one mechanism is responsible for all mass extinctions, and it is likely that many mass extinctions were the cause of several kill mechanisms acting in concert.

This book should appeal to a wide variety of scientists who have an interest in mass extinctions. It will serve as a good starting point for those interested in learning more about a particular mass extinction event, or for those interested in mass extinctions in general. This book is, therefore, highly recommended to both professionals and students.