Cretaceous/krɪˈteɪʃəs/ Definition 1 of 2Pro Tip 1/3Geological Relevance Used specifically to describe geological time, environments or fossils. Cretaceous sedimentary rocks show distinct characteristics. Pro Tip 2/3Paleontological Interest Indicates a key time for dinosaur extinction; crucial for paleontology studies. Many Cretaceous fossils provide clues about dinosaur biology. Pro Tip 3/3Predominant Flora Marked the emergence of flowering plants, affects discussions on plant evolution. The Cretaceous witnessed the rise of angiosperms.