The Earth is amazingly old, and the same area has experienced different flora and fauna and different climates such that you simply don't find modern angiosperm plants or modern placental mammals in the gullets of our cute cig smoking dinosaurs; or jungle plants when the Congo was arid, etc, etc.
You left out the part where large chunks of ground were once underwater and large chunks of the surface that are underwater used to be above ground.
The Earth has been around a long time indeed.