National Academies Press: OpenBook

Effects of Past Global Change on Life (1995)

Chapter: DISCUSSION

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Suggested Citation:"DISCUSSION." National Research Council. 1995. Effects of Past Global Change on Life. Washington, DC: The National Academies Press. doi: 10.17226/4762.
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Page 197

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GLOBAL CLIMATIC INFLUENCE ON CENOZOIC LAND MAMMAL FAUNAS 197 impoverished record. If one examines the distribution of first- and second-order episodes throughout the Tertiary, one notes a tendency for clustering of several episodes, notably in the Early Miocene, when the Arikareean associates with the two Hemingfordian episodes, and in the Late Miocene where a string of three second-order episodes is associated with the final pair of first-order episodes. Mammal Age Order Genera Hemingfordian 2 (ca. 18 Ma) Rodentia Blackia Copemys Eomys Petauristodon Carnivora Miomustela Mionictis Plithocyon Pseudaelurus Sthenictis Perissodactyla Aphelops Hemphillian 3 (ca. 5 Ma) Rodentia Mimomys Nebraskomys Promimomys Lagomorpha Ochotona Carnivora Agriotherium Chasmaporthetes Lynx Megantereon Parailurus Ursus Artiodactyla Bretzia Odocoileini Blancan 2 (ca. 2.5 Ma) Edentata Dasypus Holmesina Glyptotherium Glossotherium Eremotherium Rodentia Erethizon Neochoerus Mictomys Pliopotomys Synaptomys Carnivora Canis Tremarctos Artiodactyla Bovinae DISCUSSION During the past decade, mammalian paleontologists have discovered, somewhat to their collective surprise, that the pulse of the Cenozoic succession in North America is strongly syncopated. In particular, publication of a detailed mammalian biochronology for North America (Woodburne, 1987) underlined the unevenness of faunal turnover. The rhythm of long- stable chronofaunal intervals punctuated by rapid turnover episodes has emerged as a clear pattern (Vrba, 1985a; Webb, 1989). At the level of a continental ecosystem this pattern may be referred to as "syncopated equilibrium." The need now is for closer analysis of rapid turnover episodes to gather new insights into the mechanisms and modalities that translate environmental change into radical reorganization of terrestrial ecosystems.

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What can we expect as global change progresses? Will there be thresholds that trigger sudden shifts in environmental conditions—or that cause catastrophic destruction of life?

Effects of Past Global Change on Life explores what earth scientists are learning about the impact of large-scale environmental changes on ancient life—and how these findings may help us resolve today's environmental controversies.

Leading authorities discuss historical climate trends and what can be learned from the mass extinctions and other critical periods about the rise and fall of plant and animal species in response to global change. The volume develops a picture of how environmental change has closed some evolutionary doors while opening others—including profound effects on the early members of the human family.

An expert panel offers specific recommendations on expanding research and improving investigative tools—and targets historical periods and geological and biological patterns with the most promise of shedding light on future developments.

This readable and informative book will be of special interest to professionals in the earth sciences and the environmental community as well as concerned policymakers.

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