The Mesozoic era (the era of "middle life") is the second era of the Phanerozoic Eon, or period of visible multicellular life, which followed the Precambrian time in Earth history. The Mesozoic era began with the mass extinction event that occurred at the end of the Permian period of the Paleozoic era. The Mesozoic era consists of three geological periods, the Triassic period, the Jurassic period, and the Cretaceous period.

The single great continent of Pangaea broke apart during the Mesozoic era, to form two groups of continents, one of which would later become North America and Eurasia, the other of which would later become South America, Africa, Australia, and Antarctica.

Extinction altered the previous balance of dominance among lineages of organisms. The tree-sized club mosses, horsetails, and ferns that had dominated the forests of the middle Paleozoic era declined in importance and were extinct by the beginning of the Mesozoic era. Forests, mostly of conifers, covered most of the land surface of the Earth. One of the major lineages of arthropods, the trilobites, became extinct. Before the Mesozoic, both mollusks and brachiopods were common, but the mollusks have been more common ever since. Mammals and birds evolved from reptilian ancestors. The mammal-like reptiles and their mammalian descendants were less common in the Mesozoic than the mammal-like reptiles had previously been, and the dinosaurs evolved into a great diversity of species, many of them large. There were also many large flying reptiles and large marine reptiles.

The Mesozoic era came to an end when an asteroid collided with the Earth and created cold, dark conditions in which many species, especially large dinosaurs, could not survive.

Free term papers are not written to satisfy your specific instructions. You can use our professional writing services to buy a custom written research paper, term paper, or essay on Science at affordable price. CustomTermPapers is the best solution for those who seek help in writing term papers, essays, and research papers related to Science and other relevant topics.