Before and after land dwellers appeared, millions of species of plants and animals lived on the Earth. Some are extinct, but many are still around today. Among the extinct animals are a number of giant reptiles, including the dinosaurs. Fossil evidence suggests that dinosaurs appeared during the Mesozoic Era and disappeared at the end of that era. No one is certain what caused the extinction of the dinosaurs, other giant reptiles, and many plant and animal species.
Many scientists now believe the Earth's climate changed drastically.
The change may have been caused by a meteor shower where millions of rocks and other debris from outer space collided with the Earth. Why some species were able to endure while others, such as dinosaurs, became extinct is not yet known. Not many dinosaur fossils have been found in Kansas. During the early Mesozoic Era, erosion was fairly common in Kansas so not many animals or plants could be preserved as fossils. In the last part of the Mesozoic Era, the Cretaceous seas covered much of the state and most animals were of the marine variety.