Definition

Proper noun A specific geological time period within the Paleogene Period, spanning from approximately 40 million to 25 million years ago. It is characterized by significant global cooling and the continued evolution and diversification of mammals, including the emergence of new groups.

Usage

The term is used as a proper noun to refer to this specific interval in Earth's history. It is typically capitalized. * The Oligocene Epoch followed the Eocene Epoch and preceded the Miocene Epoch. * Many modern mammal families first appeared during the Oligocene Epoch.

Examples

• Geologists study rock formations from the Oligocene Epoch to understand ancient climates.
• The fossil record shows that grasslands expanded globally in the Oligocene Epoch.

Advanced Usage

• The term can be used attributively (like an adjective) to describe things from that period.
  • Oligocene fossils are highly prized by collectors.
  • The Oligocene climate transition was a major event.

Variants and Related Words

• Oligocene (Proper noun / Adjective): The shorter, more common form used to refer to the epoch. "The Oligocene was a time of change." or "Oligocene mammals."
• Oligocene-Miocene boundary: The transition point between the Oligocene and the subsequent Miocene Epoch.

Synonyms

• The Oligocene: A direct synonym.
• Oligocene Period (less common, as it is formally an epoch within a period).

Different Meanings / Contexts

This term has a single, specific meaning in geology and paleontology. It does not have idiomatic or figurative uses.

Noun

1. from 40 million to 25 million years ago; appearance of sabertoothed cats