Oligocene in a sentence

By contrast, the Oligocene–Miocene boundary is not set at an easily identified worldwide event but rather at regional boundaries between the warmer late Oligocene and the relatively cooler Miocene.

Cooling of the oceans had already commenced by the Eocene/Oligocene boundary, and they continued to cool as the Oligocene progressed.

Zenaida is an early-stage exploration group of concessions comprising 1,800 ha, and is also located on the Upper Eocene-Lower Oligocene (Mid-Tertiary) Metallogenic Belt, sharing some similarities to the geology in the Collahuasi region (" ").

The main factor behind the divergence in feeding strategies was probably a dramatic cooling of ocean waters during the transition from the Eocene to the Oligocene epoch, about 34 million years ago.

A Cephalogale-like species gave rise to the genus Ursavus during the early Oligocene (30–28 Mya); this genus proliferated into many species in Asia and is ancestral to all living bears.

A large question remains as to why there was a progressive decline in hypercarnivorous carnivoramorphans during the late Oligocene/early Miocene.

As in the Oligocene before it, grasslands continued to expand and forests to dwindle in extent.

At the end of the Middle Eocene Climatic Optimum, cooling and the carbon dioxide drawdown continued through the late Eocene and into the Eocene-Oligocene transition around 34 million years ago.

Brontotheres died out in the Earliest Oligocene, and creodonts died out outside Africa and the Middle East at the end of the period.

Cooling continued throughout the rest of the late Eocene into the Eocene-Oligocene transition.

During this decrease ice began to reappear at the poles, and the Eocene-Oligocene transition is the period of time where the Antarctic ice sheet began to rapidly expand.

Extensive research has gone into the fossil floras of the Paleocene to Oligocene of South-Eastern Australia, and has failed to uncover a single Eucalyptus specimen.

Following the maximum was a descent into an icehouse climate from the Eocene Optimum to the Eocene-Oligocene transition at 34 million years ago.

Formation Published estimates of the onset of the Antarctic Circumpolar Current vary, but it is commonly considered to have started at the Eocene Oligocene boundary.

If the opening occurred as late as hypothesized, then the Antarctic Circumpolar Current could not have had much of an effect on early Oligocene cooling, as it would not have existed.

In the Oligocene or Miocene, the other members, with the majority remained confined to the Old World, developed.

Its closing during the Oligocene had significant impact on both ocean circulation and climate.

Marine fossils from the Oligocene are rare in North America.

Middle Tertiary marsupials from Central Patagonia (Early Oligocene of Gran Barranca): Understanding South America’s Grande Coupure.

More recent molecular studies suggest a much younger origin, perhaps in very Late Eocene to early Oligocene periods, around 35–30 million years ago.