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. 2019 Jun 25;116(26):12698-12703.
doi: 10.1073/pnas.1821825116. Epub 2019 Jun 10.

Sixty-six Million Years Along the Road of Mammalian Ecomorphological Specialization

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Sixty-six Million Years Along the Road of Mammalian Ecomorphological Specialization

Borja Figueirido et al. Proc Natl Acad Sci U S A. .
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The fossil record of the large terrestrial mammals of the North American Cenozoic has previously been quantitatively summarized in six sequential episodes of faunal associations-"evolutionary faunas"-that correspond well with previously proposed qualitative "Chronofaunas." Here, we investigate the ecological spectrum of these faunas by classifying their major taxonomic components into discrete ecomorphological categories of diet, locomotion, and body size. To specifically address the potential influence of long-term climatic shifts on the ecomorphological composition of these faunas, we analyze via contingency tables and detrended correspondence analyses the frequency distribution of ecomorph types within faunas. We show that each evolutionary fauna has a unique, nonrandom association of ecomorphs, and we identify a long-term trend toward greater ecomorphological specialization over successive faunas during the past 66 My. Major vegetation shifts induced by climatic changes appear to underlie the ecomorphological dynamics of these six temporal associations that summarize Cenozoic North American mammalian evolutionary history.

Keywords: Cenozoic climatic change; Cenozoic mammals; ecomorphology; evolutionary faunas.

Conflict of interest statement

The authors declare no conflict of interest.


Fig. 1.
Fig. 1.
Ecomorphological analysis of the six evolutionary faunas of North American mammals. From Left to Right: dietary, locomotion, and body size categories. (A) Matrix plots performed from the number of genera weighted by species (NGwS) per ecological category distributed along the six evolutionary faunas. In the dietary categories, herbivores are plotted separately from carnivores for clarity. The ecomorph categories are ordered from Top to Bottom in increasing level of specialization, and so the predominance of warm colors (i.e., higher NGwS values) in the main diagonal stripe indicates a trend toward greater ecological specialization along the successive faunas. Denotes specialization equality (SI Appendix). The black arrows indicate the path through the successive evolutionary faunas. (B) Bivariate plots depicted from the scores of the first two axes obtained from a DCA computed from the weighted generic diversity of ecomorphs within each evolutionary fauna. (C) Bivariate plots for number of species per genus (NGwS) within each ecomorph (x axis) against faunas (y axis). See Table 1 for abbreviations.

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