Ancient ecosystems refer to the various environments that existed on Earth millions of years ago, long before modern plants and animals evolved. These ecosystems included lush forests, vast deserts, and expansive oceans, each supporting unique forms of life. Fossils found in sedimentary rocks provide clues about the types of organisms that thrived in these ancient habitats. One notable ancient ecosystem is the Carboniferous Forest, which flourished around 300 million years ago. This ecosystem was characterized by towering trees and abundant ferns, creating a rich habitat for early amphibians and insects. The decomposition of plant material during this period contributed to the formation of coal deposits we use today.