VOA慢速英语:Knife Cuts on Mastodon Bone Reveal Earlier Humans

artifact – n. a simple object made by people in the past

archeological – adj. having to do with the science of past human life and activities by studying the bones, tools, etc. of ancient people

extinct – adj. no longer existing

prehistoric – adj. relating to the time before people could write

glacier – n. a very large area of ice that moves slowly down a slope or valley or over a wide area of land

armadillo - n. an animal with a hard shell covering its body