This fun game is focused on the geology periods, whic are parts of the geologic eras. Every era from the history of life on Earth, consist of a nomber of periods and usually the eras begins and ends with some massive extinction event. A couple of eras in turn, are part of eons. Here we look closer at the Phanerozoic eon, which consists of 3 eras. We may call the first era, the era of the marine life. The second, the era of the dinosaurs. And the third, which is still in progress, the era of the mammals.
The following are all periods included in the game with their roll over descriptions:
1. PRECAMBRIAN SUPEREON - It spans from the formation of Earth about 4.6 billion years ago to the beginning of the Cambrian Period, about 541 million years ago, when hard-shelled creatures first appeared in abundance.
2. HADEAN EON - The time before the earliest-known rocks on Earth. It began with the formation of the Earth about 4.6 billion years ago and ended 4 billion years ago.
3. ARCHEAN EON - During the Archean, the Earth's crust had cooled enough to allow the formation of continents. 4 to 2 billion years ago.
4. PROTEROZOIC EON - The significant accumulation of oxygen in the Earth's atmosphere. The Proterozoic Eon extended from 2.5 billion to 541 million years ago.
5. PHANEROZOIC EON - The eon in which abundant animal and plant life has existed. It covers 541 million years to the present days.
6. PALEOZOIC ERA - It's time of dramatic geological, climatic, and evolutionary change. Fish, arthropods and amphibians evolved during the Paleozoic, lasting from 541 to 251 million years ago.
7. CAMBRIAN PERIOD - Complex, multicellular organisms gradually became more common. The Cambrian lasted 55.6 million years, from 541 million years, to 485.4 million years ago.
8. ORDOVICIAN PERIOD - The Ordovician Period began with a major extinction. Fish evolve with jaws. It spans 41.2 million years from 485.4 million years, to 443.8 million years ago.
9. SILURIAN PERIOD - The Silurian Period began with a major extinction when 60% of marine species were wiped out. Multi-cellular life began to appear on land. Spanning 24.6 million years, from 443.8 million years, to 419.2 million years ago.
10. DEVONIAN PERIOD - The first ray-finned and lobe-finned bony fish appeared. The ancestors of all tetrapods began adapting to walking on land. Spanning 60 million years, from 419.2 million years, to 358.9 million years ago.
11. CARBONIFEROUS PERIOD - Many coal beds were formed globally. Amphibians were the dominant land vertebrates. Spans 60 million years from 358.9 million years, to 298.9 million years ago.
12. PERMIAN PERIOD - Diversification of the early amniotes into the ancestral groups of the mammals, turtles. The Permian ended with the mass extinction event, when nearly 90% of marine species and 70% of terrestrial species died out. Spans 46.7 million years from 298.9 million years, to 251.90 million years ago.
13. MESOZOIC ERA - The Mesozoic Era is called the Age of Reptiles. Spans from about 252 to 66 million years ago. It begins and end with two mass extinction events, second of which is known for having killed off non-avian dinosaurs. Pangaea begins to separate.
14. TRIASSIC PERIOD - The dinosaurs, first appeared in the Late Triassic period. The first true mammals, also evolved during this period. Spans 50.9 million years, from 251.902 million years, to 201.3 million years ago. Laurasia to the north and Gondwana.
15. JURASSIC PERIOD - The first birds appeared during the Jurassic, having evolved from a branch of theropod dinosaurs. The oceans were inhabited by marine reptiles such as ichthyosaurs. Spanned 56 million years, from 201.3 million years, to 145 million years ago.
16. CRETACEOUS PERIOD - Warm climate, resulting in high sea levels, populated with now-extinct marine reptiles, ammonites and rudists, while dinosaurs continued to dominate on land. Spans 79 million years, from 145 million years, to 66 million years ago. At the end of the period, dinosaurs become extinct.
17. CENOZOIC ERA - The Cenozoic Era is the current geological era, covering the period from 66 million years ago to the present day. The separated continents begins to form their current position. Early animals were the Entelodon and Paraceratherium. Mammals and birds greatly diversify in the absence of the dinosaurs.
18. PALEOGENE PERIOD - Mammals diversified from relatively small, simple forms into a large group of diverse animals. Spans 43 million years, from 66 million years to 23 million years ago.
19. NEOGENE PERIOD - Early hominids (apes), the ancestors of humans, appeared in Africa near the end of the period. Spans 20.45 million years, from 23.03 million years, to 2.5 million years ago.
20. QUATERNARY PERIOD - Climate and environmental changes. Homo erectus was the first hominid species to widely use fire. Emergence of Black Sea and Baltic Sea. Spans from 2.5 million years ago to the present.