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Biomedical subjects

L Van Valen

Publications and source records attributed to L Van Valen.

14 recordsLinked to original sources
PubMed1971

The history and stability of atmospheric oxygen.

There are three processes weakly concentration-dependent that keep changes in concentration of atmospheric pressure from being a random walk-inhibition of net photosynthesis by oxygen, the passage of hydrogen through the oxidizing part of the atmosphere before it escapes from the earth, and burial of reduced carbon in anaerobic water. A stronger regulator seems desirable but remains to be found. The cause of the initial rise in oxygen concentration presents a serious and unresolved quantitative problem.

Air↗
PubMed1965

The earliest primates.

The known range of the Primates is extended down from the middle Paleocene to the early Paleocene and late Cretaceous by a new genus and two new species from Montana, Purgatorius unio and P. ceratops. These species approach condylarths and leptictid and erinaceoid insectivores in structure. Purgatorius is referred to a new subfamily, Purgatoriinae, of the Paromomyidae, but is probably not the stem primate. The fauna of Purgatory Hill indicates a late early Paleocene age.

Animals↗