Jademanatee's+DEVONIAN

__DEVONIAN __ By jademanatee

Introduction

410 to 360 million years ago was the [|Devonian] period. Some people call it the “Age of Fishes” because of all the new types of fish. The biggest thing that happened was fish evolving into amphibians. Also, trees and forests appeared, and that is known as the “Devonian Explosion.” Before the Devonian period was the Silurian period with the first land animals. Jawless fish, coral reefs, and other marine animals were also really common then. The weather was fairly warm so glaciers melted and water covered most of the earth. After the Devonian period was the carboniferous period where insects got bigger and trees were everywhere. All those forests eventually turned to coal. Laurasia and Godwana collided and started to form Pangea, and the earth was covered in warm and shallow water during the carboniferous period.

Abiotic

The climate and location of the [|continents] from the Devonian period were very different from how they are today. There were 2 main continents, both mostly in the southern hemisphere. Laurasia (Euramerica) was the super continent in the northern part of the southern hemisphere. It was made up of current North America, Europe and Asia. Massachusetts was in Laurasia at the southern edge of it, about 20°S. Godwana was the other landmass and its center was at about 50°S, and towards the east. South America, Africa, Antarctica, India, and Australia used to be part of Godwana. By the end of the Devonian period, Godwana and Laurasia started moving towards each other. The weather 400 million years ago was also completely different. Everywhere was warm and wet. Most of the earth was covered in shallow warm oceans where fish became amphibians. 400 million years ago, the continents and weather were different, but that’s not all.

Landforms

The Devonian period left a lot of rocks, fossils, and landforms for us to see now. Most of the rocks from then are found in Canada. Around 400 million years ago, plates collided and made mountains that are now mostly in North America. Most of the fish that fossilized are now in pieces, but not sharks, they have no fossils because their bodies are mostly cartilage. There was warm ocean everywhere so almost all the Devonian fossils are of ocean animals. One fossil of a [|Euphanerops Iongaevu], which was a Devonian fish, was found in Quebec. One invertebrate fossil found in Wisconsin is of a grammysia. Another fossil found in Quebec is of a plant called an Archaeopteris Halliana. The fossils and rocks tell us a lot about everything in the Devonian period.

Biotic

Most of the animals from the Devonian period are now extinct, but they have evolved into current creatures. By the Devonian period, fish started to have jaws, bony skeletons, and scales. The remaining jawless fish went extinct by the end, and fish started to evolve into amphibians. Water got too shallow and the fish that could were practically forced to live out of the water and on land. Lungfish, which are fish who can breathe in air, started to walk on the earth. One of the first 4-legged land animals was called a tetrapod. There were a lot of vertebrates, but also many invertebrates. Some were arachnids, but there were also millipedes and centipedes. Trilobites and graptolites disappeared towards the end of the Devonian. Most of the plants were spore plants, which are plants that need to be near the water and reproduce using spores. Seed plants also started to develop. Before the seed plants the [|Archaeopteris], which was a type of tree, was the dominant plant everywhere on earth. With the seed plants, new types of trees and forests started to appear. In the Devonian, fish were the dominant life form, but there were still other plants and animals.

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