title: Patterns of maximum body size evolution in Cenozoic land mammals: eco-evolutionary processes and abiotic forcing.
abstract: There is accumulating evidence that macroevolutionary patterns of mammal evolution during the Cenozoic follow similar trajectories on different continents. This would suggest that such patterns are strongly determined by global abiotic factors, such as climate, or by basic eco-evolutionary processes such as filling of niches by specialization. The similarity of pattern would be expected to extend to the history of individual clades. Here, we investigate the temporal distribution of maximum size observed within individual orders globally and on separate continents. While the maximum size of individual orders of large land mammals show differences and comprise several families, the times at which orders reach their maximum size over time show strong congruence, peaking in the Middle Eocene, the Oligocene and the Plio-Pleistocene. The Eocene peak occurs when global temperature and land mammal diversity are high and is best explained as a result of niche expansion rather than abiotic forcing. Since the Eocene, there is a significant correlation between maximum size frequency and global temperature proxy. The Oligocene peak is not statistically significant and may in part be due to sampling issues. The peak in the Plio-Pleistocene occurs when global temperature and land mammal diversity are low, it is statistically the most robust one and it is best explained by global cooling. We conclude that the macroevolutionary patterns observed are a result of the interplay between eco-evolutionary processes and abiotic forcing.
authors.affiliation: Department of Geosciences and Geography, University of Helsinki, , Helsinki, Finland, Department of Ecology and Evolutionary Biology, University of Tennessee, , Knoxville, TN, USA, Department of Biology, University of New Mexico, , Albuquerque, NM, USA, Department of Anthropology, University of New Mexico, , Albuquerque, NM, USA, Department of Ecology and Evolutionary Biology, University of California, , Santa Cruz, CA, USA, Department of Biology and the Ecology Center, Utah State University, , Logan, UT, USA, School of Biological Sciences, Monash University, , Victoria, Australia, Odum School of Ecology, University of Georgia, , Athens, GA, USA, Santa Fe Institute, , Santa Fe, NM, USA, Department of Paleobiology, Smithsonian Institution, , Washington, DC, USA, School of Earth and Space Exploration, Arizona State University, , Tempe, Arizona, USA, School of Biological Sciences, University of Reading, , Reading, UK, Department of Biological Sciences, University of Calgary, , Calgary, Alberta, Canada, Department of Atmospheric, Oceanic and Earth Sciences, George Mason University, , Fairfax, VA, USA.
authors.forename: Juha J
authors.initials: JJ
authors.lastname: Saarinen
authors.forename: Alison G
authors.initials: AG
authors.lastname: Boyer
authors.forename: James H
authors.initials: JH
authors.lastname: Brown
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Costa
authors.forename: S K Morgan
authors.initials: SK
authors.lastname: Ernest
authors.forename: Alistair R
authors.initials: AR
authors.lastname: Evans
authors.forename: Mikael
authors.initials: M
authors.lastname: Fortelius
authors.forename: John L
authors.initials: JL
authors.lastname: Gittleman
authors.forename: Marcus J
authors.initials: MJ
authors.lastname: Hamilton
authors.forename: Larisa E
authors.initials: LE
authors.lastname: Harding
authors.forename: Kari
authors.initials: K
authors.lastname: Lintulaakso
authors.forename: S Kathleen
authors.initials: SK
authors.lastname: Lyons
authors.forename: Jordan G
authors.initials: JG
authors.lastname: Okie
authors.forename: Richard M
authors.initials: RM
authors.lastname: Sibly
authors.forename: Patrick R
authors.initials: PR
authors.lastname: Stephens
authors.forename: Jessica
authors.initials: J
authors.lastname: Theodor
authors.forename: Mark D
authors.initials: MD
authors.lastname: Uhen
authors.forename: Felisa A
authors.initials: FA
authors.lastname: Smith
mesh_terms: D000818:Animals; D001272:Atmosphere; D044822:Biodiversity; D005075:Biological Evolution; D049628:Body Size; D005580:Fossils; D008322:Mammals / Q000502:physiology*; D010100:Oxygen / Q000032:analysis; D013696:Temperature
chemical_list: D010100:Oxygen
keywords: Cenozoic; body size; evolution; macroecology; mammals; maximum size frequency
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