The Oligocene was an epoch in Earth's history. The start of the Oligocene was marked by a major extinction event.
Visits and incursions
An Anomaly to the Oligocene opened on Oxford Street in the present, and two Entelodon came through. One was fatally gunned down in the present, while the other was tranquilised and returned through the Anomaly before it closed.
The Oligocene epoch lasted from 34 approx. to 23 million years ago. During the Oligocene, the progress of global continental drift and mountain building was continuing, while Antarctica was beginning to rapidly cool and develop its ice cap. Animals grew to greater sizes in the more open landscape, and many faunas evolved closer and closer to their modern forms.