Leaf assemblages across the Cretaceous-Tertiary boundary in the Raton Basin, New Mexico and Colorado.
Analyses of leaf megafossil and dispersed leaf cuticle assemblages indicate that major ecologic disruption and high rates of extinction occurred in plant communities at the Cretaceous-Tertiary boundary in the Raton Basin. In diversity increase, the early Paleocene vegetational sequence mimics normal short-term ecologic succession, but on a far longer time scale. No difference can be detected between latest Cretaceous and early Paleocene temperatures, but precipitation markedly increased at the boundary. Higher survival rate of deciduous versus evergreen taxa supports occurrence of a brief cold interval (<1 year), as predicted in models of an "impact winter."
Paleontology & Stratigraphy Branch, U. S. Geological Survey, MS-919, Federal Center, Denver, CO 80225.
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JA
Wolfe
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Upchurch