Geology Influencing Mammal Evolution in Mioecene Neogene North America?

Possible regional tectonic controls on mammalian evolution in western North America

Authors:

1. Malinda L. Kent-Corson (a)
2. Anthony D. Barnosky (b)
3. Andreas Mulch (c, d, e)
4. Marc A. Carrasco (b)
5. C. Page Chamberlain (f)

Affiliations:

a. Division of Earth Sciences, Nanyang Technological University, 639798, Singapore

b. Department of Integrative Biology and Museum of Paleontology, University of California, Berkeley, CA 94709, USA

c. Biodiversity and Climate Research Centre (BiK-F), 60325 Frankfurt, Germany

d. Institute of Geosciences, Goethe University Frankfurt, 60438 Frankfurt, Germany

e. Senckenberg Research Institute, 60325 Frankfurt, Germany

f. Department of Environmental Earth System Science, Stanford University, Stanford, CA 94305, USA

Abstract:

Previous work has suggested that tectonically active regions act as speciation pumps for mammals and plant species, but little is known about how fast or widespread tectonism must be in order to directly influence evolution. Here, we use oxygen and hydrogen isotopic data from Miocene sedimentary deposits to characterize the topographic evolution of the southern Columbia Plateau/Snake River Plain and northern Rocky Mountain regions during the Yellowstone hotspot passage, with the ultimate goal of understanding whether topographic changes caused by the hotspot influenced mammalian evolution within those regions. We conducted oxygen isotope analyses of 130 samples of lacustrine, and paleosol carbonate from Miocene stratigraphic sections that span much of the northern Rocky Mountain region, and combined these data with previously published isotopic records. Collectively these isotopic data show that caldera formation associated with the Yellowstone hotspot has modified regional topography and rearranged drainages along the track of the hotspot, and that the hotspot has left a topographic depression in its wake.

We explore the extent to which these topographic changes influenced or are decoupled from diversity changes exhibited by the local mammal faunas and conclude that the passage of the hotspot and consequent surface uplift created rainshadows in the lee of high-elevation calderas and/or generated large volumes of volcanic materials, influencing soils and vegetation. Collectively, that may explain a possible rise in mammal diversity in the CP/SRP region at ~ 14 Ma, coincident with a drop in diversity in the NRM. It is still unclear, however, how different taphonomic pathways and sample-standardization problems are influencing apparent diversity peaks at this temporal and geographic resolution.