First adapt radiation after Ordovician Period was the Silurian period, This happened about 443.7 - 416 years ago and after the first extinction. (N/A,N/A) This was the beginning of fresh water fish, plants and animals left the water to be on land. This began the terrestrial form of life with plant being assigned to the cooksonia genus and the vascular systems of complex plants. this period was subdivided into four epochs which had stages. (Fischer,Liu, Yip, and Yu, 1998)
The next period was the Devonian around 408 - 360 million years ago and the Carboniferous Period, about 359.2 - 299 million years ago and after the second extinction. this was divided in to two subsystems the Pennsylvanian and the Mississippian which were subdivided to stages. (Waggoner, 1996) This was a time of the first appearance of amphibians, bony fish, sharks and the diversity of terrestrial life. Also came the beginning of reptiles, the diversity of amphibians, conifers and the first coal beds. (Klappenbach,N/A,)
Next was extinction which is the largest extinction in history. (Alexander, Chang, Tsai, and Wu, 1998) This was the time of diversification of insects and reptiles, with the expansion of conifers. (Klappenbach,N/A,)
Triassic comes after the forth extinction about 248 - 246 million years ago and was divided into seven epochs.( Asaravala, Lam, Litty, Phillips and Wu, 1998) This brings the first dinosaurs the diversity of bony fish, reptiles, many insects and conifers. (Klappenbach,N/A,)
The Jurassic period brought dinosaurs roaming the earth, the first of birds and mammals, more insect, conifers and the diversity of bony fish. the earth had a tropical climate and flowering plants had not evolved yet. when the seas rose North America was flooded and this also go birth to the Atlantic Ocean. (N/A,N/A)
We now go into the Cretaceous, tertiary and quaternary periods between 144 million years ago and the present. near the end of the Cretaceous period was the fifth extinction and the extinction of dinosaurs. This also brought the first modern fish, birds and angiosperms are dominant. In these periods we have the diversity of placental mammals, modern and grazing mammals, primates(anthropoid), many birds, humans origin and family, hominies and the start of the sixth extinction. (Klappenbach,N/A,)
The sixth extinction is more biotic than physical, which is caused by man. How man causing this destruction by transforming the landscape, exploitation of species to the maximum, pollution and bring in alien species. This extinction is divided into two phases, first when man began moving to other parts of the world some 100,000 years ago. part two started 10,000 years ago when man got into agriculture. Man over hunted certain species and may even brought diseases to species that never had human contact before. Man is destroying ecosystems more species are...