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Contains the most recent episodes of global cooling, or ice ages, took place in the Pleistocene. Much of the world's temperate zones were alternately covered by glaciers during cool periods and uncovered during the warmer interglacial periods when the glaciers retreated.

It is a time of great change in terrestrial vegetation. The early Mesozoic was dominated by ferns, cycads, and other unusual plants. Modern gymnosperms, such as conifers, first appeared in their current recognizable forms in the early Triassic. By the middle of the Cretaceous, the earliest angiosperms had appeared and began to diversify, largely taking over from the other plant groups.

The breakup of Pangaea, which began to during the Jurassic, continued leading to increased regional differences in floras and faunas between the northern and southern continents.

The end of the Cretaceous brings the end of many previously successful and diverse groups of organisms, such as non-avian dinosaurs and ammonites. This opened the stage for groups which had previously taken secondary roles to come to the forefront. The Cretaceous was the time in which life as it now exists on Earth came together.

Named for the Jura Mountains on the border between France and Switzerland, the Jurassic has become a household word. It is important to us today, both because of its wealth of fossils and because of its economic importance: The oilfields of the North Sea, for instance, are Jurassic in age.

Roughly halfway in between, animals, fungi, and plants alike colonized the land while insects took to the air. 

During this time there were six major continental land masses; each of consisted of different parts of the modern continents. These Paleozoic continents experienced tremendous mountain building along their margins and numerous incursions and retreats of shallow seas across their interiors. 

Many Paleozoic rocks are economically important. For example, much of the limestone quarried for building and industrial purposes, as well as the coal deposits of western Europe and the eastern United States, were formed during the Paleozoic

 Also two major animal groups colonized the land. The first tetrapods, or land-living vertebrates, appeared and the first terrestrial arthropods, including wingless insects and the earliest arachnids. In the oceans, brachiopods.  Crinoids and other echinoderms, tabulate and rugose corals, and ammonites were also common. Many new kinds of fish appeared

A subdivision of the Early Cambrian is the Tommotian (530 to 527)

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Proterozoic: 2,543-543. Many exciting events in the Earth's history and of life occurred during this time. Stable continents first appeared and began to grow. Also the first abundant fossils of living organisms, mostly bacteria and archaeans, but by about 1.8 billion years ago eukaryotic cells appear as fossils too. In the beginning of the Middle Proterozoic comes the first evidence of oxygen build-up in the atmosphere. This spelled doom for many bacterial groups, but made possible the explosion of eukaryotic forms. These include multicellular algae, and toward the end of the Proterozoic, the first animals.

Archean: 3,800-2,500. The Archean is divided into early, middle, and late. It's early in the Archaean that life first appeared on Earth. The oldest fossils date to roughly 3.5 billion years ago, and consist of bacteria microfossils. All life during the Archaean was bacterial.  These include mounds of stromatolites, colonies of photosynthetic bacteria which have been found as fossils in Early Archaean rocks of South Africa and Western Australia. Stromatolites increased in abundance throughout the Archaean, but began to decline during the Proterozoic. They are not common today.

Hadean: : 4,500-3,800. Hadean time is not a geological period as such. No rocks on the Earth are this old - except for meteorites. During Hadean time, the Solar System was forming, probably within a large cloud of gas and dust around the sun, called an accretion disc. The relative abundance of heavier elements in the Solar System suggests that this gas and dust was derived from a supernova, or supernovas - the explosion of an old, massive star. Heavier elements are generated within stars by nuclear fusion of hydrogen, and are otherwise uncommon. We can see similar processes taking place today in so-called diffuse nebulae in this and other galaxies.