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Limits to randomness in paleobiologic models: the case of Phanerozoic species diversityThe question of how random, or unconstrained, paleobiologic models should be is examined with a case study: Signor's (1982, 1985) inverse calculation of levels of marine species diversity through the Phanerozoic. His calculation involved an ingenious model that estimated species numbers and species abundances in the world oceans of the past by correcting known numbers of fossil species for variations in sedimentary rocks available for sampling and in effort paleontologists might devote to sampling. The model proves robust to changes in possible shapes of species-abundance distributions, but it is sensitive to alterations in the assumption that paleontologists collect fossils at random. If it is assumed that ease of collecting varies with age of sediment (with the Cenozoic offering easy sampling) or that paleontologists tend to seek out rarer fossils, results of the inverse calculation change. In particular, the magnitude of the calculated Cenozoic diversity increase always declines from the factor of about seven as originally reported to something considerably smaller. This leaves open the problem of the magnitude of Cenozoic increase in marine species diversity, awaiting better empirical data and, perhaps, more exacting models, random or otherwise.
Document ID
20040121518
Acquisition Source
Headquarters
Document Type
Reprint (Version printed in journal)
Authors
Sepkoski, J. J. Jr
(University of Chicago Illinois 60637, United States)
Sepkoski JJ, J. r.
Date Acquired
August 22, 2013
Publication Date
January 1, 1994
Publication Information
Publication: Acta palaeontologica Polonica
Volume: 38
Issue: 4-Mar
ISSN: 0567-7920
Subject Category
Geosciences (General)
Funding Number(s)
CONTRACT_GRANT: NAGW-1693
Distribution Limits
Public
Copyright
Other
Keywords
Non-NASA Center
NASA Discipline Exobiology

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