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

NOTE: See also http://bodysize.nescent.org. 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 (≈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 concentra..., Sizes of the Largest Fossils in the Geological RecordThis table contains taxonomic, size, and source information describing the largest known fossil plants, animals, protists, and prokaryotes in the fossil record. The prokaryote record covers only the Archaean and early Paleoproterozoic. The protist, animal, and vascular plant records cover all relevant geological periods from the Paleoproterozoic through the Neogene. See also http://bodysize.nescent.org.Supplementary Dataset FINAL 3.xls