The Neogene Expansion

The Neogene Expansion (23 - 2.59 MYA) manifested the cooling of the Earth and the modernisation of animals. Grasslands continue to expand with many herbivores speccing into grazing. The climate and biomes placed increased evolutionary pressure. India joined with Asia and Italy was pushed into Europe.

## In the Oceans

A warming event followed the global cooling that thickened Arctic ice cap grew but this did not stop permanent ice sheets from draping Antartica. Sea levels plummeted, exposing land bridges between Africa and Eurasia and between Eurasia and North America to allow for more migration. Pinnipeds (seals, sea lions, and walruses) and cetaceans (whales and dolphins) diversified in response to these changing conditions. Fossils from this period reveal the appearance of early forms of familiar groups, such as the first true seals and ancestors of the modern toothed and baleen whales.

Other notable aquatic builds at the time includes:

* Kelp - large, brown seaweed that established new habitats
* Megalodon - the biggest shark of all time, being 15 - 18 meters long)
* Vasum - sea snail bearing a conical spire shell with spines),

## On Land

The cooling and drying of the Earth extended deserts and grasslands. Many mammal groups colonised new continents during the Neogene, crossing land bridges. For example, ancestral camels, originating in North America, crossed to Eurasia about 7 million years ago where they later evolved into Dromedaries and Bactrian camels.

Increasing in prominence, grassland biomes gave rise to a new mode of feeding among herbivores, grazing. This was a buff to even-toed ungulates, especially ruminants, were better suited to eating the coarse grasses that are low in nutritional value than than odd-towed ungulates; due to their more highly developed stomachs. Ruminants have four chambered stomachs with microbes that digest cellulose. Diversification of artiodactyls, such as cattle and antelopes, came at the expense of perissodactyls, such as horses and rhinos. The artiodactyls started herding together for safety as they forage. They would evolve to become bigger and faster to evade their predators. Meanwhile, carnivores started speccing into the intelligence and mobility skill tree and came up with strategies, such as pack hunting and pursuit hunting respectively.

This expansion also witnessed the emergence of early humans. The first Hominin species, such as Sahelanthropus and Ardipithecus, evolved during this time. These early human ancestors were adapted to both arboreal and terrestrial environments.

Other notable builds on land at the time includes:

* Phalacrocorax - Old World Cormorants with long bills with a hook
* Argentavis - One of the largest birds ever with strong legs and a scavenger
* Thylacosmilus - sabre-toothed, carnivorous relative to marsupials
* Enaliarctos - earliest known relative to Pinnipeds with crude flippers
* Teleoceras - a rhinoceros with a hippopotamus-like form
* Paraceratherium - a giant rhinoceros with long necks
* Chalicotherium - large odd-toed ungulate with claws
* Aardvark - burrowing, nocturnal insectivore akin to anteaters
* Amphicyon - carnivorous mammals that look like a dog with bear-like features