It may be protected by law because its numbers are low, but the low numbers likely are related to where the animal is found. An animal endemic to the state is restricted to a location or region. The great rivers that flowed during the ice age regularly flooded the Delta, depositing sediment on the alluvial plain in eastern Arkansas.įour E’s are used to examine the status of an animal population: endemic, endangered, extirpated, and extinct. The Mississippi Alluvial Plain is the best place to look for fossils of prehistoric mammals, such as the sloth, the woolly mammoth, the mastodon, saber-toothed tiger, the short-faced skunk, and the giant beaver. Chalky areas in the Southwestern Coastal Plain yield many other warm sea creatures, including bivalves and worm tubes. Shark, turtle, crocodile, and a variety of fish fossils have been found there. Fossils of larger animals, including dinosaurs, have been found in the West Gulf Coastal Plain. The land that formed the Ouachitas was in a deep sea basin, churning with sediment, so few fossils are found there. ![]() Because the land that formed the Ozarks and parts of the Arkansas River Valley was once a shallow inland sea, the rocks there are studded with the fossils of marine invertebrates. The state’s oldest fossils are in the uplands, including the Ozark Mountains, the Arkansas River Valley, and the Ouachita Mountains. ![]() If they had a hard shell or a bony skeleton, fossil records tell the story. Many types of animals that lived here have disappeared. ![]() During warm periods, the glaciers melted and sent millions of gallons of water through Arkansas on its way to the sea. They did not reach Arkansas but occurred as far south as the Missouri River. The most recent drastic climate change began about 1.6 million years ago during the Pleistocene epoch, the planet’s most recent ice age. The climate has ranged from tropical, supporting dinosaurs in the Mesozoic period, to the cold period at the end of the Cenozoic period, known as the Pleistocene epoch. Arkansas has undergone many changes over geologic time.
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