3,900 million years ago

3,900-2,500 million years ago

Archaean period – the earliest marine life form (blue-green algae)

2,500-540 million years ago

Proterozoic period – the first many-celled organisms evolve

540-490 million years ago

Cambrian period – the first fossils of animals with shells and skeletons

490-443 millions years ago

Ordovician period –molluscs, some corals and fishlike vertebrates

443-417 million years ago

Silurian period – fish develop jaws; first sharks

417-354 million years ago

Devorian period – fish dominant; amphibians (the first land animals) evolve

354-290 millions years ago

Carboniferous period – insects; first reptiles

290-248 millions years ago

Permian period – insects evolve into modern types; reptiles evolve

248-206 million years ago

Triassic period – early dinosaurs; marine reptiles

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Names of months

The names of the months in English (as well in many other languages) come from Latin Words. January Januarius – this month was dedicated to Janus, the Roman god of doors. Janus had two faces, one looking back at the old year and the other looking forward to the new year. February Februarius – Februa was the Roman purification festival, which took place at this time of year. March ...

Chinese calendar

Present-day China uses the Gregorian calendar for most purposes, but traditional festivals, such as Chinese New Year, take place according to the ancient Chinese calendar. Legend has it that this was started during the reign of Emperor Huangdi in 2637 BC, and relates to the positions of the Moon and Sun. Heavenly systems Earthly branches 1 jia 1 zi (rat) 2 yi ...

Constellations

Groups of stars form patterns in the night sky, which are called constellations. There are 88 known constellations. The sumerians, a Middle Eastern civilization, probably named them, about 5,000 years ago. The largest is Hydra, the sea serpent, and the smallest is Crux Australis, the Southern Cross. Centaurus, the Centaur. Has the most stars that can be seen with the naked eye(94). Others include Aquila, the Eagle; Canis Major, the Great Dog; and Orion, the Hunter.

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