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Explore the geologic time scale, sequencing Earth's history through eons, eras, periods, and epochs. Learn about major events like the Precambrian era, Paleozoic era with ancient life forms, Mesozoic era featuring dinosaurs, and Cenozoic era with current life forms.
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The geologic time scale divides Earth’s history based on major past events.
Index fossilscan provide the relative age of a rock layer. • existed only during specific spans of time • occurred in large geographic areas fusulinids trilobites
The geologic time scale organizes Earth’s history.Divided into eons, eras, periods, and epochs. Precambrian 4.5 bya – 544 mya Oldest rocks/fossils Origin of eukaryotes Cyanobacteria 88% of geologic time
Paleozoic “ancient life” 544-248 mya, fish, arthropods, amphibians, reptiles • Mesozoic “middle life” 248-65 mya reptiles, dinosaurs, birds, small mammals, fish • Cenozoic “recent life” 65 mya –present mammals, primates, fish, birds