Cretaceous Time Period
The last stage of Mesozoic era, which is commonly known as Cretaceous period, had nearly 80 million years of long duration. However, in the beginning of this age and end of the Jurassic period, very insignificant or negligible extinction has been recorded such as bivalve mollusks species. |
In the Cretaceous period, the landmasses recorded significant changes. This included the separation of Laurasia and Gondwana and the development of North Atlantic Ocean towards the eastern side of Laurasia that spread over the east coast of North America and many parts of Western Europe.
On the other side, South America and Africa split up in the Gondwana. The earth's crust pulled apart and created the space for oceans. This space finally resulted to the South Atlantic Ocean and a sequence of submerged volcanic mountains. With the increase in the volume of the ocean, the mountains also got the way to grow and dislodged water, causing the formation of local seas.
An extra rift towards the eastern side of Africa formed a watercourse between Africa, Madagascar and India.
Similar to the Jurassic period, faunal species, especially dinosaurs, kept on developing. The most important development was the appearance of herbivorous and bird-hipped ornithoschian ceratospian dinosaurs. One of the examples is triceratops, which had 3 horns and bony plate skull. Tyrannosaurus rex, a theropoid and carnivorous dinosaur, was the most prominent dinosaur of this period.
Almost no changes were recorded in the extinction of aquatic animals during this period. The giant sea reptiles continue to prey on fish, mollusks and arthropods.
Appearance of many species of plants and flowers was the main character of this period. Many new plants came into existence that were later recognized as the ancestors of the plants in forest trees such as magnolia and the maple. Many varieties of insects such as butterflies, ants, termites and bees came into existence. These insects sucked their food from flowers and in return spread the pollens of one flower to another, aiding in the reproduction process.
Except for dinosaurs and placental mammal, there was no notable development in this era.
More Articles :
|
