Final answer:
During the Paleocene, the climate was tropical; the Eocene was hot with subtropical regions even at higher latitudes; the Oligocene saw gradual cooling and some aridity; the Miocene remained mild despite a global cooling trend.
Step-by-step explanation:
Climate During Different Geological Periods
The climate during the Paleocene, Eocene, Oligocene, and Miocene periods varied significantly. The Paleocene (about 66-56 million years ago) was a time of tropical to subtropical conditions where temperatures were generally higher than today. During the Eocene (about 56-34 million years ago), the climate was hot and the Earth experienced one of its warmest periods in history, allowing subtropical vegetation like palm trees to grow in regions such as Wyoming, which points to a warm subtropical climate. Through the transition to the Oligocene (about 34-23 million years ago), the climate began cooling, leading to some arid conditions and set the stage for further cooling in the late Oligocene.
The Miocene (about 23-5.3 million years ago) saw a further global cooling trend but was still characterized by a generally mild climate compared to today, allowing the continued diversification of flora and fauna. The Tertiary Period overall was warmer and more humid than the Quaternary Period, which started around 2.6 million years ago and experienced a series of ice ages. The Pliocene epoch, as part of the Tertiary, marked a pivotal time with colder conditions than the Miocene, leading to changing sea levels and more ice at the poles.