New Colorado fossil record documents life’s rebound after Cretaceous-Paleogene extinction

Nearly 66 million years ago, the reign of dinosaurs ended and the ascendency of mammals on Earth began. While this changing of the taxonomic guard is well recognized, the details remain unclear. Now poised to change that, a collection of fossils embedded in the rocks of central Colorado’s Corral Bluffs, described in a new study, provides previously unknown details about how Earth’s terrestrial plant and animal species recovered following the Cretaceous-Paleogene extinction (KPgE) event. Fossils of the terrestrial survivors who inherited Earth after this major extinction are otherwise extremely rare.

Tyler Lyson and colleagues studied an extensive fossil-rich deposit in Colorado’s Denver Basin. Its fossil finds offer a detailed snapshot of the first million years of taxonomic and ecological recovery following extinction, revealing a dynamic interplay between plants, animals, and climate. Maximum mammalian body size increased by three-fold at ~300 ka post-KPgE, the authors say, associated with increased richness in megafloral species. Detailed records of post-mass extinction ecological rebound, such as this, may provide important insights for predicting ecosystem recovery following catastrophic extinction events including the one we currently face, the authors say.

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