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The Geologic Time Scale - Devonian

ERA

PERIOD

AGE
(of start)

Cenozoic

Quaternary

1.6 my

Tertiary

65 my

Mesozoic

Cretaceous

140 my

Jurassic

205 my

Triassic

250 my

Paleozoic

Permian

290 my

Carboniferous

355 my

Devonian

410 my

Silurian

438 my

Ordovician

510 my

Cambrian

540 my

Devonian 410 - 355 million years ago

Life

Dominant life includes:
Fish, amphibians, insects, land plants

The first known tetrapods (land-living vertebrates) and terrestrial arthropods (wingless insects and early arachnids) appeared during this time.

Fish diversified into many new forms.

Major extinction event occured at the end of the Devonian, killing 50% of species.

Climate

North America, China and Australia were dry at the beginning of the Devonian, but as the land masses moved close toward each other, the area became very wet and warm. South America and Africa were close to the South Pole and were cool and mainly covered by water.

Geology

Collision of northeastern North America with Europe raise Appalachian Mountains. (Acadian Orogeny)

The main rock types/ deposits in PA are shale, sandstone, and conglomerate.

Silurian
Carboniferous
 
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