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| | Geologic Periods |
 | | Life-forms in the Triassic Period were arthropods, turtles, crocodilians, true lizard, bony fishes, sea urchins, early dinosaurs, marine reptiles, and the therapsids, the first mammal-like reptiles appear. |
 | | Life-forms in the Jurassic Period were flying reptiles, dinosaurs, earwigs, conifers, redwood, cypress, yew, cycads, ginkgoes, and the early mammalian dicynodonts. |
 | | The Cretaceous Period was the final Period of the Mesozoic Era and extended from 144 Million to 65 Million Years Ago. |
| imnh.isu.edu /geo_time/geo_time_periods.htm (606 words) |
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