1974 - Donald Johanson and Tom Gray discover a 3.5 million-year-old female hominid fossil that is 40% complete and name it "Lucy"
1980 - Luis Alvarez, Walter Alvarez, Frank Asaro, and Helen Michel propose that a giant comet or asteroid may have struck the Earth approximately 65 million years ago thereby causing massive extinctions and enriching the iridium in the K-T layer
1984 - Hou Xianguang discovers the Chengjiang Cambrian fossil site
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