Paleoecology is the study of past ecosystems and how they have changed over time. This field of research uses fossil evidence, such as pollen grains, plant remains, and animal bones, to reconstruct ancient environments and understand how they were structured, how species interacted with each other, and how they responded to environmental changes. By studying the interactions between organisms and their environments in the past, paleoecologists can gain insights into how modern ecosystems may respond to ongoing and future environmental changes.