Researchers who study the fossil record are seeking to determine whether the impact made by a comet or meteor really did decimate up to half of the life on this planet at the end of the Cretaceous period. Questions whether the extinction of plant and animal life was abrupt, started before the impact, or was a gradual change. (KR)

Discusses how genetic data on present human population relationships and data from the Pleistocene fossil hominid record are being used to compare two contrasting models for the origin of modern humans. (TW)

The islands of western Lake Erie are rock-bound isles that abound in rocky outcrops and quarries. The rocks of these islands are of two distinct types, Silurian dolomites and Devonian limestones. The dolomites, exposed in the Bass Islands and Sister Islands are virtually devoid of fossils. Conversely, the limestones of Johnson Island, Marblehead,…

Presented is a discussion of recent evidence on the evolution of human forms on earth gathered and evaluated using mitochondrial DNA techniques. Theories regarding the possibility that a common female ancestor existed in Africa about 200,000 years ago are discussed. A list of teaching aids is provided. (CW)

The major concepts inherent in studies of organism-substrate interrelationships as a whole are critiqued. Various modes, styles, processes and products of marine sediment bioturbation are described. Shortcomings of the present state of research knowledge on this topic are discussed. Listed are 154 references. (CW)

Selection and acquisition of relevant materials for building and developing an information infrastructure are modern worldwide problems. This document provides a core listing of journals in the earth sciences in an effort to develop a tool for the improvement of information handling and transfer. The core list was generated using several databases…

Presented are the arguments of two different points of view on the mass extinction of the dinosaurs. Evidence of extraterrestrial impact theory and massive volcanic eruption theory are discussed. (CW)

Discusses some parallels that seem to exist between mass extinction recognizable in the geologic record and the impending extinction of a significant proportion of the earth's species due largely to tropical deforestation. Describes some recent theories of causal factors and periodicities in mass extinction. (Author/TW)

Questions a hypothesis from creation science dealing with mammals. Claims that, when tested, the hypothesis fails in two ways. (TW)

Presented is a review of important science news stories of 1989 as reported in the pages of "Science News." Topics include anthropology, astronomy, behavior, biology, biomedicine, chemistry, environment, food science, math and computers, paleobiology, physics, science and society, space sciences, and technology. (CW)

Describes some of the contributions made by the field of paleontology to theories in geology and biology. Suggests that the two best examples of modern evolutionary paleontology relate to the theory of punctuated equilibria, and the possibility that mass extinctions may be cyclic. (TW)

Presented are the three main theories that describe the pattern of evolution of geographic variants of H. sapiens--the multiregional model, the out-of-Africa model, and the gene-flow or hybridization model. The contributions of geneticists, paleoanthropologists, and the history of fossils are included. (KR)