Search Results

The disappearance of nonavian dinosaurs is only a small part of a greater class of extinctions known as “mass extinctions.” Mass extinctions are global events characterized by unusually high rates of extinction. The five episodes of mass extinctions in Earth history are the Permo-Triassic extinction, the Late Ordovician extinction, the Late Devonian extinction, the Triassic-Jurassic extinction, and the Cretaceous-Tertiary (K/T) extinction. This chapter focuses on patterns of geologic and biotic changes that occurred during the Cretaceous-Tertiary (K/T) extinction. It also highlights the similarities and differences in interpretations of geologic and fossil records. It concludes with two scenarios explaining the differing views about dinosaur extinction.

This chapter examines the social and political meaning of dinosaur paleontology in popular culture. It considers three case studies: the paleobiology of the large theropod T. rex, the discovery of dinosaur maternity, nests, eggs, and embryos, and the dinosaur extinction. The analysis reveals that important discoveries about the biology, behavior, and extinction of dinosaurs were influenced not just by empirical developments, but also by the social climate of the times in which they were produced.

Nuclear war analysts often compared nuclear detonations to volcanic eruptions. The connection between volcanic eruptions and climatic changes, suggested long ago by Benjamin Franklin and others, received serious interest from researchers only in the early twentieth century. Today, however, a direct comparison between volcanic eruptions and nuclear war is deemed inappropriate owing to the different absorption properties of sulfuric acid and silica dust than dark smoke. Furthermore, the distributions of particle sizes are different, and warfare would give rise to fine particles from a variety of sources rather than a single location. This chapter examines scientific disciplines with less obvious connections to nuclear war, including volcanic eruptions, ozone depletion, planetary studies, dinosaur extinction, and the asteroid impact hypothesis.

The federal government was hopelessly in a dilemma about nuclear winter, concerned that it might force a reconsideration of its national policy. The military was less apprehensive, recognizing quite early the significance of these studies and showing a willingness to obtain honest advice. In 1982, the National Academy of Sciences was conducting a study to evaluate the link between dinosaur extinction and dust, rather than nuclear winter. Meanwhile, the Department of the Navy, always technologically oriented, made its own efforts to keep informed about nuclear winter. In 1983, Carl Sagan advocated “minimal deterrence” and encouraged a “build-down” to the approximate nuclear winter threshold level of 100 MT by the end of the century. He also presented a layman’s summary of the physical and biological consequences of nuclear war as recently determined by his TTAPS team (comprised of Richard Turco, Owen Brian Toon, Thomas Ackerman, James Pollack, and himself) and their colleagues.