The Mesozoic geological era consists of three geological periods, namely Triassic, Jurassic and Cretaceous. The Triassic period (248 to 206 million years ago) paved the way for the Dinosaurs' reign on earth and the formation of the giant continent called Pangaea occurred during the same period. Then came the Jurassic period (206 to 144 million years ago) which saw the complete domination of the Dinosaurs on earth. The Bony fish was the superior creature in the sea and the historians say that this era saw the evolution of the first mammals. The dominant land plant was Gymnosperms and a group of Dinosaurs named Theropods developed feathers to defend against the cold just like the fur in the animals.
The earth was undergoing drastic changes during the Jurassic era. The climate was hot and dry during this period and the evolution of the flowering of plants began during this time. Different types of Dinosaurs began to appear and they include Sauropod dinosaurs, Diplodocus, Apatosaurus, Allosaurus and Compsognathus. There was a mass extinction during the early part of the Jurassic period and a lot of marine species became nonexistent. During the middle part of the Jurassic era the continent Pangaea began to drift apart and in the later part of the period, the division reached its final phase. The continent Pangaea broke apart into three separate continents of North America, Eurasia and Gondwana during the last stage.
The polar ice was absent during Jurassic period and that was the reason why the sea levels were reasonably higher than it is today. As mentioned earlier, the formation of the super continent during the Triassic period made the climate of the Jurassic period dry and desert like. During the middle time, because of the drifting of the Pangaea vast flooded areas, subtropical forests and coral reefs came into existence. As a resultant factor the seasonal changes were a bit moderate than it is now. The continental rift also was instrumental in giving birth to a small Atlantic ocean in between North America and Eurasia.
The resultant peculiar condition was congenial for the rapid growth of the forests across the continents and the Conifers dominated the trees in these forests. The Jurassic ecosystems were really congenial for the survival of the Dinosaurs. The airways became haunted with more and more flying reptiles and it was the beginning stage of the evolution of birds. The diversification of the nature was the prime responsible factor for the recently evolved species to find their different ecological niches. The evolution of dinoflagellates and nanoplankton ,the dominating factors of the micro life of ocean, paved the way for the Phytoplankton to find the most congenial surrounding to survive. Phytoplankton is a microscopic, plant-like organism which is an indispensable element in the most food chains even today. Large reefs were also reinstated in the shallow sea. All these factors contributed immensely towards the rapid evolution of fishes and other types of sea animals which we see today.
During the beginning of the Jurassic era the climatic conditions were undergoing rapid changes and the presence of the carbon dioxide was at its highest ever. Humid forests were available not only at the equators alone but also it was spreading mid-latitudes to the poles. During the later stages of Jurassic period the climate was more on side of subtropical and humid nature and it was more congenial for life. Though there were Conifers such as Araucarioxylon was the dominating trees. Land plants such as Club mosses, Horsetails and Ferns were also present in the land. The Horsetails was the favorite food item for the plant eating Dinosaurs. Since this plant had underground stems which could regrow, the extinction of this plants was not possible for Dinosaurs. The predominant land animals were Dinosaurs of various types and the ocean life was dominated by long-necked Plesiosaurs, Sharks, Marine Crocodiles and Rays. Creatures like cephalopods, ichthyosaurs and shelled ammonites were also available in the ocean and Sponges and Mollusks were prevalent in plenty.
The Jurassic period is named after the Jura Mountains where rocks of this age were first studied and the mountains exist between France and Switzerland. What makes Jurassic era absolutely relevant in these days? The wealth of fossils and the economic importance like the oilfields of the North Sea, make it the best period of all time.