The Miocene epoch (23.03 to 5.333 million years ago) saw the spread of grasslands. This was a significant shift in the Earth's vegetation, leading to the evolution of many new herbivores and carnivores adapted to this new environment.

Here's why:

* Climate Changes: The Miocene saw a cooling and drying trend, leading to the expansion of grasslands across the globe. This was particularly prominent in Africa, North America, and Eurasia.

* Evolution of Grasses: Grasses themselves were evolving and becoming more diverse, making them better adapted to the changing conditions.

* Herbivore Adaptations: Animals like horses, rhinos, and antelope evolved specialized teeth and digestive systems to efficiently graze on grasses.

* Predator Adaptations: Predators like saber-toothed cats, wolves, and hyenas also diversified, becoming better adapted to hunting in the open grasslands.

So, while the Miocene epoch is known for many significant events, the spread of grasslands was a key development that shaped the evolution of life on Earth.