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Landscape properties have a profound influence on the diversity and distribution of biota, with present-day bio- diversity hot spots occurring in topographically complex regions globally. Complex topography is created by tec- tonic processes and further shaped by interactions between climate and land-surface processes. These processes enrich diversity at the regional scale by promoting speciation and accommodating increased species richness along strong environmental gradients. Synthesis of the mammalian fossil record and a geophysical model of topographic evolution of the Basin and Range Province in western North America enable us to directly quantify relationships between mammal diversity and landscape dynamics over the past 30 million years. We analyze the covariation between tectonic history (extensional strain rates, paleotopography, and ruggedness), global temperature, and diversity dynamics. Mammal species richness and turnover exhibit stronger responses to rates of change in land- scape properties than to the specific properties themselves, with peaks in diversity coinciding with high tectonic strain rates and large changes in elevation across spatial scales. 

The Cenozoic landscape evolution in southwestern North America is ascribed to crustal isostasy, dynamic topography, or lithosphere tectonics, but their relative contributions remain controversial. Here we reconstruct landscape history since the late Eocene by investigating the interplay between mantle convection, lithosphere dynamics, climate, and surface processes using fully coupled four-dimensional numerical models. Our quantified depth dependent strain rate and stress history within the lithosphere, under the influence of gravitational collapse and sub-lithospheric mantle flow, show that high gravitational potential energy of a mountain chain relative to a lower Colorado Plateau can explain extension directions and stress magnitudes in the belt of metamorphic core complexes during topographic collapse. Profound lithospheric weakening through heating and partial melting, following slab rollback, promoted this extensional collapse. Landscape evolution guided northeast drainage onto the Colorado Plateau during the late Eocene-late Oligocene, south-southwest drainage reversal during the late Oligocene-middle Miocene, and southwest drainage following the late Miocene. 

Within extreme continental extension areas, ductile middle crust is exhumed at the surface as metamorphic core complexes. Sophisticated quantitative models of extreme extension predicted upward transport of ductile middlelower crust through time. Here we develop a general model for metamorphic core complexes formation and demonstrate that they result from the collapse of a mountain belt supported by a thickened crustal root. We show that gravitational body forces generated by topography and crustal root cause an upward flow pattern of the ductile lower-middle crust, facilitated by a detachment surface evolving into low-angle normal fault. This detachment surface acquires large amounts of finite strain, consistent with thick mylonite zones found in metamorphic core complexes. Isostatic rebound exposes the detachment in a domed upwarp, while the final Moho discontinuity across the extended region relaxes to a flat geometry. This work suggests that belts of metamorphic core complexes are a fossil signature of collapsed highlands.