Oligoceen

The Oligocene is a geological epoch that spans from approximately 33.9 to 23 million years ago. It is the third epoch of the Paleogene Period, following the Eocene and preceding the Miocene. This epoch witnessed significant changes in global climate, flora, and fauna.

During the Oligocene, the Earth's climate began to cool and dry, leading to a reduction in tropical forests and the expansion of grasslands. This environmental shift had a profound impact on the evolution of mammals. Many modern mammalian orders diversified and appeared during this time, including the ancestors of horses, rhinoceroses, cats, dogs, and primates. The rise of grasslands provided new ecological niches, favoring herbivores with specialized teeth for grinding tough vegetation and predators adapted to hunting in more open environments.

The formation of the Antarctic ice sheet began in earnest during the Oligocene, contributing to the global cooling trend. Ocean currents also shifted, influencing climate patterns worldwide. In the plant kingdom, the cooling and drying climate led to the decline of lush, warm-climate forests and the proliferation of more temperate and arid-adapted vegetation, such as conifers and deciduous trees.

Fossil evidence from the Oligocene provides a glimpse into a world transitioning from the warm, humid conditions of the Eocene to the more varied climates of later epochs. The epoch is characterized by the emergence of many familiar mammal groups, setting the stage for the continued diversification of life in the subsequent Miocene.