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. However, three types of dinosaurs did live along the Kansas shoreline. Fossils of Sylvisaurus, Heirosaurus, and Claosaurus have been discovered.
Sylvisaurus and Heirosaurus were armored dinosaurs. The Sylvisaurus grew to 10 feet in length and the Heirosaurus to 20 feet. The Claosaurus stood on its hind legs, grew up to 12 feet in height, and had a duck bill. Like many dinosaurs, the Sylvisaurus, Heirosaurus, and Claosaurus were herbivores, or plant eaters.
Another unusual reptile, the pterosaur, dominated the Kansas skies during the Mesozoic Era. Although the pterosaur could fly, it probably had hair rather than feathers on its wings. Fossils of pterosaurs found in Kansas have wingspans under 20 feet, but larger pterosaurs have been found in other places.
The plants and animals that were able to survive into the Cenozoic Era often are more familiar to us. Thousands of fossils of plants, insects, amphibians, reptiles, birds, fish, and mammals have been found in Cenozoic rocks in Kansas.
During the Cenozoic Era, large mammals began to appear. Mammals such as the mastodon, woolly mammoth (ancestor of the elephant), rhinoceros, camel, tiger, peccary (wild pig), and bison roamed through Kansas in the early part of the era. By the time people began making Kansas their home, many of these animals were extinct or had migrated to other parts of the world. The bison, one of the few large animals that did survive, almost became extinct when thousands were slaughtered by hunters in the 1800's. Even though an assortment of wild animals still live in Kansas, most seem tiny compared to the giant mastodons and mammoths.
Figure 29. This diagram shows the size (in feet) of several animals that lived in Kansas at one time or another. Dimetrodon fossils have been found in Permian rock. Mosasaurs and pterosaurs lived in western Kansas during the Cretaceous. The Teleoceras, a rhinoceros, lived in Kansas in the Tertiary Period, and mammoths traveled in herds on the plains during the early Quaternary Period.