Dinopedia
Register
Advertisement
Neogene

The Neogene Period is a geologic period that lasted from about 23.03 million years ago to 2.588 million years ago. The Neogene period consists of the Miocene, and Pliocene epochs. The Neogene Period follows the Paleogene Period, and is followed by the Quaternary period. The Neogene is the second of the 3 periods in the Cenozoic to have occurred so far.

The terms Neogene System (formal) and upper Tertiary System (informal) describe the rocks deposited during the Neogene Period.

The Neogene period ended at the end of the Pliocene epoch, just before the beginning of the Quaternary Period. However, there is a movement amongst geologists (particularly Neogene Marine Geologists) to also include ongoing geological time (Quaternary) in the Neogene, while others (particularly Quaternary Terrestrial Geologists) insist the Quaternary to be a separate period of distinctly different record. The somewhat confusing terminology and disagreement amongst geologists on where to draw what hierarchical boundaries, is due to the comparatively fine divisibility of time units as time approaches the present, and due to geological preservation that causes the youngest sedimentary geological record to be preserved over a much larger area and reflecting many more environments, than the slightly older geological record. By dividing the Cenozoic era into three (arguably two) periods (Paleogene, Neogene, Quaternary) instead of 7 epochs, the periods are more closely comparable to the duration of periods in the Mesozoic and Paleozoic eras.

During this period, mammals and birds continued to evolve into modern forms, while other groups of life remained relatively unchanged. Some continental movement took place, the most significant event being the connection of North and South America at the Isthmus of Panama, late in the Pliocene. This cut off the warm ocean currents from the Pacific to the Atlantic Ocean, leaving only the Gulf Stream to transfer heat to the Arctic Ocean. The global climate cooled considerably over the course of the Neogene, culminating in a series of continental glaciations in the Quaternary Period that follows.

Marine and continental flora and fauna have a modern appearance. The reptile group Choristodera became extinct in the early part of the period, while the amphibians known as Allocaudata disappeared at the end. Mammals and birds continued to be the dominant terrestrial vertebrates, and took many forms as they adapted to various habitats. The first hominins, the ancestors of humans may have appeared in southern Europe and migrated into Africa. The first humans (belonging to the species Homo habilis) appeared in Africa near the end of the period.

In response to the cooler, seasonal climate, tropical plant species gave way to deciduous ones and grasslands replaced many forests. Grasses therefore greatly diversified, and herbivorous mammals evolved alongside it, creating the many grazing animals of today such as horses, antelope, and bison. Eucalyptus fossil leaves occur in the Miocene of New Zealand, where the genus is not native today, but have been introduced from Australia.

References[]

Template:FootnotesSmall

Template:Cenozoic Footer Template:Neogene Footer

Advertisement