Macroevolutionary changes in the fossil plant record: Key examples from the Cretaceous-Paleogene of Patagonia, Argentina

Abstract

Clearly, past and present plant diversity is due to the many evolutionary processes that are the manifestation of the organisms’ responses to changes in the environment. Most current evolutionary studies (such as population genetics, epigenetic mechanisms, phylogeography, and phylogenetics) provide information on a few generation-times and are focused on microevolutionary events. Some of these studies have as major goals the estimation of divergence times, construction of phylogenies, and explanations of biogeographical distributions. Nevertheless, the majority of these studies use fossils only as calibration points and mostly ignore critical information that only fossils can provide about the course of evolution in general. Herein, we reevaluate macroevolutionary changes that are critical for understanding past and present diversity and provide concrete examples in deep time (Cretaceous-Paleogene) from several sites in Patagonia, Argentina. We discuss Extinction, Retraction, Expansion, Diversification, and Coevolution (Codiversification) processes that have significantly shaped modern Patagonian vegetation.