To dream of fossils represents your awareness of something that happened a long time ago that you don’t care about anymore. Outdated beliefs, behaviors, or ways thinking. Consider the object that is fossilized for additional meaning.
Alternatively, a fossil may reflect your awareness of how dangerous a situation used to be. Discovering how ignorant, unsafe, or incompetent something used to be. Awareness of wisdom and progress.
Positively, a fossil may reflect your relief that people are not acting so dangerous, ignorant, or primitive anymore.