NEOGENE

Paleogeography

The uplifting of the Alps, Dinaric Alps, Hellenides and Taurids mountain ranges intensified when the African and Eurasian plates collided in early Neogene. When these mountain ranges were formed, the eastern Tethys split into two parts, the southern Tethys and the northern Tethys, known as Paratethys. The two parts of Tethys were linked by the present-day Pannonian Basin and the Black and the Caspian Sea. Some 15 million years ago, freshwater inflow made Paratethys into an enormous lake. At the same time, the collision of the African and Eurasian plates disconnected Tethys from the Indo-Pacific, and the Mediterranean Sea was formed. Approximately six million years ago, glacial periods in the Antarctica region caused the global sea levels to drop and the Mediterranean Sea to desiccate, which is known as the Messinian Salinity Crisis. Some 5.5 million years ago, Paratethys broke up into a number of smaller lake basins such as the Pannonian, Dacian, Aegean, Black Sea, Caspian and Aral basins. The Mediterranean Sea started to fill up from the Atlantic at the same time. The lake basins derived from Paratethys for the most part dried out or formed smaller lakes such as the Balaton Lake, the Caspian Sea or the Aral Sea. 

Paleoclimate

In early Neogene, climate again became warmer, but in the next period it changed once again, and the world became colder and drier. In the north hemisphere, North and South America were pushed together by intensive tectonic activity that caused an expansion of the Atlantic Ocean. This resulted in the formation of the Isthmus of Panama, which stopped the North Atlantic Current from entering the Pacific, changing its course and pushing it back toward north-western Europe as the warm Gulf Stream. North and in particular South Pole ice sheets expanded at the same time. Ocean temperatures and global sea levels dropped. Deserts formed in Africa and Asia. Forests gradually disappeared and were replaced by steppes, prairies and savannas. It was the onset of another ice age. Their occurrence was the most common in the past 1.8 million years.

Terrestrial life

Fauna – The Neogene was the time of frogs, rats, mice and snakes, with the birds going through their greatest peak period. Some of the largest bird species to ever inhabit the Earth, such as the Titanis (1), lived in this period. Several types of even-toed and odd-toed ungulates developed in the Neogene. Megaloceros (2), a genus of deer, is an important representative of even-toed ungulates, and the odd-toed ungulate Merychippus (3), the size of a present-day pony, is the ancestor of the modern horse. The Merychippus evolved into the Hyperion, a small, slender pony resembling an antelope, which was replaced by the Pliohippus, resembling the modern horse. Rhinoceroses and elephants were the most important representatives of the Proboscidea order. The woolly rhinoceros (5) was the most important rhinoceros, and the mastodon Amebelodon (6) was the most important ancestor of modern-day elephants.  They inhabited all continents except Australia and Antarctica. Neogene was also the time of carnivores, in particular the Felidae such as the sabre-toothed tiger (7), and the Ursidae, which weighed more than a tonne (8).

Primates developed in particular during the Neogene. New World monkeys (flat-nosed monkeys) (9), Old World monkeys (snub-nosed monkeys) (10) and anthropoid monkeys (Hominidae) (11) appeared.

Fauna – The colder climate in the second half of the Neogene changed the vegetation. Forests disappeared, to be replaced by herbaceous plants, grasses, weeds and bushes, with or without small clumps of trees. The sudden development of grasses and herbaceous plants was beneficial for the development of rodents, mice and rats (12), and consequently also the development of snakes. Insects flourished in this period, and consequently also frog and songbirds.

Marine life

In early Neogene, coral reefs were expanding in the still warm seas, where numerous molluscs bivalves and gastropods thrived, along with brachiopods, arthropods and worms. Firmer algae covers appeared, making the reefs more resistant to ocean waves. The drop in sea temperatures since Mid-Neogene caused the diatoms and the planktonic foraminifera to flourish. The development of sharks (12) continued. A new whale species that feed on plankton appeared (13), the baleen whales. Dolphins (14) also appeared as a separate group of marine mammals. 

Velebit sedimentary basin

In the Neogene, sedimentation in the Velebit area was highly localised and limited to remaining isolated lakes. Some of the sedimentary basins were occasionally linked during their evolution, but neotectonics movements caused by further collision of the Adriatic Microplate and the already uplifted Dinaric Alps caused them to shrink in size. There are almost no Neogene sediments in the Velebit area, because Velebit was already fully uplifted by that time, and the sediment material is only found in the surrounding valleys. The formation of rockfall breccias, called Velebit breccias, continued only at the very top of the Velebit.

Extinction

There was no mass extinction event in the Neogene on the scale of previous global extinction events, but there were 18 ice ages.