Collaborative Research: Depicting Rocky Mountain landscapes and vegetation through the warmest interval of the last 66 million years

Plant fossils from the early Eocene (56 to 48 million years ago) are abundant in Wyoming, Colorado, and Utah, providing excellent glimpses of the forests that thrived in and around the Rocky Mountains during Earth’s last great hothouse interval. This project will study 12 fossil sites, including the iconic Yellowstone and Green River Formation floras. Using cutting-edge technologies and methods, the team aims to improve the age constraints of each site, identify the plant species present, observe insect feeding damage on the fossil leaves, and reconstruct the ancient environments. By comparing sites, the team will learn how and why forests change across mountainous regions and communicate these insights through public outreach. The 12 study sites span a range of geographic locations (northern Wyoming to Utah and Colorado) and paleoenvironmental settings (high elevation, mountain-proximal, basin interior, proximal to great inland lakes). Project objectives are to (1) obtain more precise dates for the sites; (2) develop a comprehensive taxonomic dataset of fossil plants across all sites with attention to leaves, flowers, fruits, seeds, and pollen; (3) document insect folivory damage on host plants; and (4) infer paleoenvironmental conditions using sedimentology, floristics, and functional traits. The team will then compare floristic composition, host-specific insect folivore damage, paleoecology, and paleoenvironmental reconstructions across sites to investigate the relative importance of environmental conditions, biotic interactions, dispersal, and chance in determining forest composition and ecology. Finally, the team will compare these Rocky Mountain assemblages with coeval floras from Eurasia and the Neotropics to address how early Eocene warming affected intercontinental plant dispersal. The project will test fundamental hypotheses about community assembly ecological interactions and biogeographic connectivity during a major Cenozoic hothouse interval. All fossil plant descriptions will be openly accessible through PBot (the Integrative Paleobotany Portal), facilitating synthetic research at regional to global scales. Outreach will involve building an augmented reality experience that lets users travel virtually back in time ~50 million years to explore ancient forests and learn about fossil plants. The team will conduct “Road Shows” at five Wyoming communities close to the study sites and hold a public paleontology symposium at the University of Wyoming Geological Museum. 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.