14/09/2021 · Here, we present detrital zircon dates that indicate that the maximum composite age of Santa Rosa is 29.6 ± 0.08 Ma (Lower Oligocene), although several zircons from Santa Rosa date to the Upper Oligocene.

The Oligocene is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present (33.9±0.1 to 23.03±0.05 Ma). The Oligocene is the third and final epoch of the Paleogene Period. The Oligocene is often considered an important time of transition, a link between the archaic world of the ...

Oligocene Epoch, third and last major worldwide division of the Paleogene Period (65.5 million to 23 million years ago), spanning the interval between 33.9 million to 23 million years ago. The Oligocene Epoch is subdivided into two ages and their corresponding rock stages: the Rupelian and the Chattian .

The Oligocene epoch (39 to 22 million years ago) is the transition period between the earlier and later Tertiary period (65 to 2 million years ago). A key feature of evolution is the ripple effect created by geographical changes that influence climate and therefore vegetation and ultimately the ways in which animals develop.

Most of the important climatic events that many scientists believe should mark the beginning of the Oligocene (e.g., the global oxygen isotope shift indicating the expansion of Antarctic glaciers, and related events such as the cooling on North America) are earliest Oligocene (magnetic Chron C13N, about 33 million years ago) using the hantkeninid criterion.