The Cretaceous period was the last and longest segment of the Mesozoic Era, spanning from approximately 145 to 66 million years ago. It was a time of significant geological, climatic, and biological changes, with the breakup of the supercontinent Pangaea leading to the formation of the Atlantic Ocean. The Cretaceous period is well-known for the diversification and dominance of dinosaurs, including large herbivorous sauropods and theropods like Tyrannosaurus rex. It also saw the emergence of flowering plants, the evolution of modern mammals, and the extinction of the dinosaurs at the end of the period. The study of the Cretaceous period is important for understanding Earth's history, climate change, and the evolution of life on our planet.