The era that gave us modern mammals and vast grasslands

Space · Published 31 October 2026 Swipe more like this →

In short: Imagine a world where the blueprints for today's land animals were finalized. During the Miocene, Earth underwent a radical transformation as global warming paved the way for two of our most defining ecosystems: sprawling grasslands and underwater kelp forests.

Spanning from 23 million to 5.3 million years ago, the Miocene Epoch serves as a pivotal chapter in the Neogene Period. It was a time of climatic transition where global temperatures were generally warmer than those of the preceding Oligocene or succeeding Pliocene eras. This warmth, followed by subsequent cooling, drove significant environmental shifts, most notably the drying of continental interiors which allowed for the first major expansion of grasslands. The period is divided into three main epochs: Early, Middle, and Late. Scientists also categorize these layers into six distinct ages. These include the Aquitanian, Burdigalian, Langhian, Serravallian, Tortonian, and Messinian stages.

For biologists, the Miocene is a cornerstone of mammalian evolution. By this period, land-dwelling mammals were essentially modern in form; many archaic groups had already vanished by the end of the Oligocene. The fossil record from this era is so rich that fully half of all mammalian families known today are present within it. It was also a period of intense diversification for horses, primarily in North America, featuring genera like Parahippus and Merychippus, alongside the first appearances of dogs and bears. The fossil record includes remains of Moropus, a clawed ungulate related to horses. This genus is found in both Asian and North American deposits. Additionally, the bear-dog Hemicyon emerged around the same time as early bears.

The era also saw significant geographical shifts in biodiversity. While there was an interchange of fauna between the Old and New Worlds in the Northern Hemisphere, as well as between Africa and Eurasia, South America and Australia remained isolated. These geological and climatic dynamics created a mosaic of environments, from terrestrial landscapes to the first marine kelp forests, setting the stage for the modern biological world. Important geological deposits from this era are located across several continents. Key sites include India, Mongolia, East Africa, and Pakistan. These locations provide a comprehensive view of both marine and terrestrial environments.

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