Cenozoic Era: Neogene & Quaternary Periods 

23 Ma–Present

The Neogene: towards the modern

Reaching to the present day, life during the Neogene (23–2.6 Ma) and Quaternary (2.6–present) Periods didn't look too much different from what we can observe on the modern Earth. The continents were close to their present positions; the largest mountains on Earth, the Himalayas, were being formed from the collision of India and Asia; and climate was relatively more seasonal than in previous times., though there were both warming and cooling periods, such as the Middle Miocene Climatic Optimum and the Quaternary Glaciation, respectively. With respect to the latter ice age, some animals were evolutionarily equipped to deal with cooling conditions, like mastodons and woolly mammoths, and otherwise several mammals became quite large, like the giant ground sloth, Megatherium. These large animals, much like in the Mesozoic during the age of dinosaurs, were prey to the exceptional hunters of the time, for instance, Smilodon, the saber-toothed cat shown here (of course we had to incorporate a "tiger" of some sort for our own mascot here at Mizzou!). While the Quaternary is officially ratified on the base of the magnetic polarity chronozone known as the Matuyama Chron (or C2r), it also somewhat nicely corresponds with the appearance of the Homo genus that all humans belong to, though not yet Homo sapiens. The evolution and expansion of Homo sapiens, along with the development of civilization and industrialization, certainly and irrevocably changed the shape of the biosphere, but for how long we will maintain our foothold is ultimately at the mercy of the Earth, as observed many times in life's history.