Earth's History - Geologic Time Scale

Set: Earth's History - Geologic Time Scale

Familiarize		Learn		Test
Play Scatter			Play Space Race

	Term	Definition
	Era	the larger of the two subdivisions of earth's history
	Period	subdivision of eras
	Precambrian Era	4.6 million - 545 million years ago
	Precambrian Era	Oldest, longest era, land is formed 4.6 billion years ago by volcanoes
	Precambrian Era	Bacteria and green algae forms during this time
	Paleozoic Era	545 million years ago – 250 mya
	Paleozoic Era	Vertebrates appear (fish, and other animals that have a backbone)
	Paleozoic Era	Then amphibians form (can live outside of water but lay eggs in water such as frogs
	Paleozoic Era	All continents come together in one big land mass called Pangaea
	Paleozoic Era	Largest mass extinction at the end (most living things die)
	Mesozoic Era	250 mya – 65 mya
	Mesozoic Era	“The age of reptiles” (reptiles are cold blooded, have scales, lay eggs)
	Mesozoic Era	The first birds and dinosaurs appear
	Mesozoic Era	Ends in another mass extinction called the KT event that kills dinosaurs 65 million years ago which gives rise to mammals
	Cenozoic Era	65 million – present day
	Cenozoic Era	“age of the mammals” (born alive, have hair or fur, young are fed milk, warm blooded)
	Cenozoic Era	homo sapiens appear (that’s people)