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

Department of Geological and Environmental Sciences, Stanford University, 450 Serra Mall, Building 320, Stanford, CA 94305, USA.
Proceedings of the National Academy of Sciences (Impact Factor: 9.81). 12/2008; 106(1):24-7. DOI: 10.1073/pnas.0806314106
Source: PubMed

ABSTRACT 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 (approximately 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.

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Available from: Michal Kowalewski, Aug 03, 2015
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    • "Body Size.—Major overall increases in average and maximum size of marine organisms occurred over the Phanerozoic (Bambach 1993, 1999; Trammer 2005; Novack-Gottshall 2008; Novack-Gottshall and Lanier 2008; Payne et al. 2009). Within clades or faunas over shorter time intervals, however, patterns are less clear. "
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