Untitled presentation (9).pdf - 12 Periods in the Geologic time scale Ashionna Lanier Integrated Science 1A Credit 1 Precambrian Period Earth forms

Untitled presentation (9).pdf - 12 Periods in the Geologic...

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°± Periods in the Geologic time scale Ashionna Lanier Integrated Science °A Credit °
Precambrian Period Ɣ Earth forms; continental shields appear; fossils are rare Ɣ ²³´ Billion Years Ago Ɣ !8µ¶ of the geologic record Ɣ ·²° Ma
Cambrian Period Ɣ Shelled marine invertebrates appear; trilobites and brachiopods are common³ Ɣ ··³´ Ma Ɣ Known as “Cambrian Explosion” Ɣ “The time of Ancient Life” Ɣ Marked a dramatic burst of evolution
Ordovician Period Ɣ Echinoderms appear; brachiopods increase Ɣ ²!8!8³¸ Ma Ɣ The area north of tropics was nearly ocean Ɣ Was nearly ocean Ɣ Now it¹s an ocean
Silurian Period Ɣ ²²² ma Ɣ Eurypteridsº land plants and animals appear Ɣ No Land plants Ɣ Today it’s more animals and land plants
Devonian Period Ɣ ²°´ ma Ɣ Age of fish begins Ɣ Amphibians appear
Carboniferous Period

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