Fossil evidence refers to the preserved remains or traces of ancient organisms found in sedimentary rocks. These fossils can include bones, teeth, shells, and even footprints, providing crucial information about the structure and behavior of extinct species. By studying these remains, scientists can learn about the evolution of life on Earth and how different species adapted to their environments over time. Fossils are often dated using methods like radiometric dating, which helps determine their age and the geological period they belong to. This evidence is essential for understanding the history of life, including major events like the Cambrian Explosion and mass extinctions, which shaped the diversity of organisms we see today.