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Biomedical subjects

D M Raup

Publications and source records attributed to D M Raup.

25 records · Page 2Linked to original sources
PubMed1986

Completeness of the geological record.

The completeness of a sedimentary section of known timespan may be assessed qualitatively by comparing its thickness with the average accumulation for that timespan. Average accumulations may be estimated from sediment volume and continental area data. Quantitative completeness estimation methods based on data compiled from the geological literature have been proposed, but we argue that the literature data are significantly biased and cannot support such methods. Interestingly, however, a comparison of the literature data and accumulation averages computed from sediment volume data suggests that the thickest known sections may be extremely complete.

Earth, Planet↗
PubMed1985

Magnetic reversals and mass extinctions.

Previous analyses of the time distribution of reversals of the Earth's magnetic field have yielded mixed results. Some authors have claimed significant periodicities of order 10(7) yr whereas others have reported failure to reject null hypothesis of random spacing at that scale. Because of repeated suggestions that field reversal is linked to biological extinction, further analysis of the magnetic times series is appropriate. I present here the results of a study of the reversal record of the past 165 Myr. A stationary periodicity of 30 Myr emerges (superimposed on the non-stationarities already established by others), which predicts pulses of increased reversal activity centered at 10, 40, 70, ... Myr BP.

Biological Evolution↗
PubMed1984

Periodicity of extinctions in the geologic past.

The temporal distribution of the major extinctions over the past 250 million years has been investigated statistically using various forms of time series analysis. The analyzed record is based on variation in extinction intensity for fossil families of marine vertebrates, invertebrates, and protozoans and contains 12 extinction events. The 12 events show a statistically significant periodicity (P less than 0.01) with a mean interval between events of 26 million years. Two of the events coincide with extinctions that have been previously linked to meteorite impacts (terminal Cretaceous and Late Eocene). Although the causes of the periodicity are unknown, it is possible that they are related to extraterrestrial forces (solar, solar system, or galactic).

Animals↗
PubMed1983

Multiple origins of life.

There is some indication that life may have originated readily under primitive earth conditions. If there were multiple origins of life, the result could have been a polyphyletic biota today. Using simple stochastic models for diversification and extinction, we conclude: (i) the probability of survival of life is low unless there are multiple origins, and (ii) given survival of life and given as many as 10 independent origins of life, the odds are that all but one would have gone extinct, yielding the monophyletic biota we have now. The fact of the survival of our particular form of life does not imply that it was unique or superior.

Biological Evolution↗
PubMedDate not supplied

Nonconscious intelligence in the universe.

Animals lacking humanoid intelligence have evolved systems indistinguishable in function, if not in structure, from systems built by humans. Although radio communication has never been verified in animals, it is completely feasible biologically. If such systems are present in non-intelligent organisms on other planets, then our chances of detecting life in the universe by current SETI methods are greatly enhanced.

Animal Communication↗