Silurian and Devonian Periods

The Silurian Period and Devonian Period
The Silurian (443.7 to 416.0 million years ago) was a time when the Earth underwent considerable changes that affected the One result of these changes was the melting of large glacial formations. This contributed to a substantial rise in the levels of the major seas. The Silurian witnessed a relative stabilization of the Earth's general climate, ending the previous pattern of erratic climatic fluctuations.

The Climate of The Devonian
During the Devonian there were important changes in the land masses on the globe. North America and Europe had collided forming a large continent called Euramerica. This caused the formation of the Appalachian Mountain Range. The other large land mass was Gondwana. It was made up of South America, Africa, Antarctica, India and Australia. These two large land masses lay close to one another near the equator.
The two continents were moving toward each other throughout the Devonian Period. The waterway between the two continents covered a subduction zone. This is an area where one plate is moving underneath the other. Eventually this would mean that the two continents would collide to form the supercontinent Pangea in the Permian Period. That event is more than 64 million years after the Devonian Period.


Major Evolutionary Events

  • The development of vascular plants, pollen and seeds provided plants with a way to reproduce and survive on dry land, creating new habitats.The development of jaws allowed fishes and other emerging vertebrates to catch larger prey.The development of tetrapods—limbed animals—would pave the way for animals that could walk on land.
  • Diversified marine life developed jaws.
  • Arthopods developed legs to evolved on land
  • Plants were rigid stems had no leaves, developed into mosses due to the hot and humid climate.

Mass Extinctions causes and Impacts on Life

  • The causes for the mass extinctions were due to the major fall in sea leveland then the onset of glaciation over the African and south American portion of Gondwana.

  • The extinctions of 85% Ordovician species occured and also the death of many marine life species.

APA Citation
Tour through time. In (2007). Retrieved from

National geographic. In (2009). Retrieved from

The devonian period:the age of the fish. In (2006). Retrieved from

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