The rise of ocean giants: maximum body size in Cenozoic marine mammals as an indicator for productivity in the Pacific and Atlantic Oceans
Nicholas D. Pyenson, Geerat J. Vermeij
Published 5 July 2016.DOI: 10.1098/rsbl.2016.0186
Fig. 1. (a,b) Maximal body size in North Pacific and North Atlantic marine mammal herbivores, and (c,d) similarly for mammalian filter-feeders, during the Cenozoic. PhyloPics of herbivores, except Hydrodamalis, by Steven Traver.
Large consumers have ecological influence disproportionate to their abundance, although this influence in food webs depends directly on productivity. Evolutionary patterns at geologic timescales inform expectations about the relationship between consumers and productivity, but it is very difficult to track productivity through time with direct, quantitative measures. Based on previous work that used the maximum body size of Cenozoic marine invertebrate assemblages as a proxy for benthic productivity, we investigated how the maximum body size of Cenozoic marine mammals, in two feeding guilds, evolved over comparable temporal and geographical scales. First, maximal size in marine herbivores remains mostly stable and occupied by two different groups (desmostylians and sirenians) over separate timeframes in the North Pacific Ocean, while sirenians exclusively dominated this ecological mode in the North Atlantic. Second, mysticete whales, which are the largest Cenozoic consumers in the filter-feeding guild, remained in the same size range until a Mio-Pliocene onset of cetacean gigantism. Both vertebrate guilds achieved very large size only recently, suggesting that different trophic mechanisms promoting gigantism in the oceans have operated in the Cenozoic than in previous eras.
All additional data are in the electronic supplementary material file.
N.D.P collected the data. N.D.P. and G.J.V. analysed the data, wrote the manuscript, approved the final draft of the manuscript and agree to be held accountable for the content herein.
We have no competing interests.
N.D.P. is supported by the Smithsonian Institution, its Remington Kellogg Fund, and the Basis Foundation. All figures are our own.
We thank J. Vélez-Juarbe for help with data collection and four anonymous reviewers along with A. H. Fleming, J. A. Goldbogen, A. O'Dea, J. F. Parham, C. M. Peredo and J. Vélez-Juarbe for helpful comments.
Received March 3, 2016. Accepted June 13, 2016.
© 2016 The Authors.
Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited.
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