A recently discovered Cretaceous mammal called maotherium is a chipmunk-sized nocturnal mammal that lived 123 million years ago. The chipmunk-sized creature had terrestrial habits and scampered around on the ground. Maotherium weighed about 2 ounces and was 15 cm (5 inches) in length. Scientists say the tiny creature is revealing more about how mammal's complex ear bones evolved.
Photo: Mark A. Klingler/Carnegie Museum of Natural History
