How the Earth Began- Biology (measured in millions of years) By fre6214 120 Apperance of flowering plants Period: 150 to 205 Jurassic Period 205 Fourth mass extinction Period: 205 to 250 Triassic Period 220 The first dinosaurs and mammals 250 Third mass extinction Period: 250 to Mar 2, 2022 Permian Period 350 Early reptiles Period: 360 to Mar 2, 2022 Devonian Period 370 Early Amphibians 400 Bony fishes become abundant Period: 435 to 505 Ordovivian Period 440 First Mass extinction 445 Plants and arthropods invade land; jawed fishes first start to appear 500 Animal diversity abounds: first jawless fishes Period: 500 to 540 Cambrian Period 510 Origin of all major animal phyla Period: 540 to Jan 1, 600 Precambrian Era Jan 1, 700 Earliest multicellular Organisms Jan 1, 1000 Diverse protists Jan 1, 1500 First eukaryotes Period: Jan 24, 1908 to Jan 24, 1975 Tertiary Period The dates is reallt frokm 8-75. It keeps change it to 1908-1975. Period: Mar 2, 2022 to 360 Carboniferous Period Jan 1, 2500 Origin of Oxygen by Photosynthesis Jan 1, 2750 Earliest fossil bacteria