NSF Award
2317671
During the Cretaceous/Paleogene (K/Pg) mass extinction (ca. 66 million years ago), ~75% of all species on Earth went extinct, notably including all non-avian dinosaurs. This event completely changed the trajectory of the evolutionary tree of life, leading ultimately to the formation of today’s mammal-dominated communities. The aftermath of the K/Pg mass extinction represents a natural laboratory in which ecosystem reorganization can be studied with high geologic resolution. Some studies have been undertaken to examine how marine ecosystems were rebuilt, but the response of terrestrial environments is poorly documented. This project will examine ecological and environmental changes that occurred on land across the K/Pg boundary in the Rocky Mountain region of the western United States. The research will involve extensive paleontological and geochemical analyses of existing fossil collections and introduce novel data that will reveal the variability in the timing and pattern of terrestrial ecosystem rebuilding after the mass extinction. This project will expand knowledge of a major turning point in the history of life on Earth that will help determine how the biodiversity of ecosystems recover at the continental scale and how modern terrestrial biota evolved. The results may also provide data for conservation biologists to predict the long-term consequences of current rapid changes in biodiversity and help inform conservation priorities to alleviate ecosystem disruptions. The project will use established programs in classrooms, museum exhibits, and outreach at the participating institutions to reach audiences of multiple ages and backgrounds.<br/><br/>The K/Pg mass extinction completely changed the trajectory of the evolutionary tree of life and most research has focused on marine systems. Post-extinction patterns of ecosystem restructuring on land, fundamental to understanding the evolution of the modern taxa of mammals and plants, have received little attention because fossil collections, data, and high-resolution chronostratigraphic sections are relatively rare. This project will build on extensive fossil collections from three primary study areas in the Western Interior of North America, involve new fieldwork designed to augment collections and data from critical intervals, and develop diverse inorganic and organic geochemical records to characterize and identify biotic patterns, local environments, and factors involved in terrestrial ecosystem restructuring following the K/Pg extinction. To accomplish these goals, the research team will: collect and interpret megafloral, palynological, invertebrate, and vertebrate fossils and associated contextual data from three well-studied stratigraphic sections; use fossil leaf physiognomic traits and geochemical data from organic compounds to construct records of temperature, precipitation, and fire frequency; integrate ecological proxies of community structure and environmental conditions over time and space as they relate to the three study areas, to determine if there are any climatic conditions, geographic locations, or trophic interactions that enhance or impede ecosystem restructuring after the K/Pg extinction. In addition, geochemical proxies for volcanic activity will be examined to resolve the influence of the extensive basalt eruptions of the Deccan Traps on the biota within the study areas.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
