Two-phase increase in the maximum size of life over 3.5 billion years reflects biological innovation and environmental opportunity

The maximum size of organisms has increased enormously since the initial appearance of life >3.5 billion years ago (Gya), but the pattern and timing of this size increase is poorly known. Consequently, controls underlying the size spectrum of the global biota have been difficult to evaluate. Our...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2009-01, Vol.106 (1), p.24-27
Main Authors: Payne, Jonathan L, Boyer, Alison G, Brown, James H, Finnegan, Seth, Kowalewski, Michał, Krause, Richard A. Jr, Lyons, S. Kathleen, McClain, Craig R, McShea, Daniel W, Novack-Gottshall, Philip M, Smith, Felisa A, Stempien, Jennifer A, Wang, Steve C
Format: Article
Language:English
Subjects:
Animals
Atmosphere
Atmospherics
Biological Evolution
Biological Sciences
Body size
Body Size - genetics
Environment
Eukaryotic Cells
Evolution
Fossils
Geology
History, Ancient
Oxygen
Paleobiology
Physical Sciences
Precambrian strata
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Summary:The maximum size of organisms has increased enormously since the initial appearance of life >3.5 billion years ago (Gya), but the pattern and timing of this size increase is poorly known. Consequently, controls underlying the size spectrum of the global biota have been difficult to evaluate. Our period-level compilation of the largest known fossil organisms demonstrates that maximum size increased by 16 orders of magnitude since life first appeared in the fossil record. The great majority of the increase is accounted for by 2 discrete steps of approximately equal magnitude: the first in the middle of the Paleoproterozoic Era ([almost equal to]1.9 Gya) and the second during the late Neoproterozoic and early Paleozoic eras (0.6-0.45 Gya). Each size step required a major innovation in organismal complexity--first the eukaryotic cell and later eukaryotic multicellularity. These size steps coincide with, or slightly postdate, increases in the concentration of atmospheric oxygen, suggesting latent evolutionary potential was realized soon after environmental limitations were removed.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.0806314106