History of the Earth By ClintCAPtnilC Apr 10, 1800 Humans Apr 10, 1803 Dinosaurs Apr 10, 1808 First hard shelled animals Apr 10, 1818 First cells with nucleus Apr 10, 1820 Rise in atmospheric oxygen Apr 10, 1835 Apex Chert earliest fossils Apr 10, 1839 Isua First Sedimentary Evidence for Oceans and Earliest Isotopic Evidence for life Apr 10, 1900 Acasta Oldest Rock Apr 10, 1901 Oldest Zircon Crystal 4.4 Billion years old Apr 10, 1902 Moon Formation Moon Formation Apr 10, 1903 Formation of Core Apr 10, 1904 Formation of Earth Period: Jan 1, 2000 to Apr 1, 2011 0 to Now