The Neogene
Species Spread Out
The continental connections gave animals that had evolved in isolation access to new lands. Elephants and apes wandered from Africa to Eurasia. Rabbits, pigs, saber-toothed cats, and rhinos went to Africa. Elephants and rhinos continued across the Bering Strait to North America. Horses went the other way. Ground sloths migrated from South America to North America; raccoons scurried south. Even rodents may have hopped Pacific islands en route to Australia from Southeast Asia.
As the climate changed, many of the great forests that carpeted the continents from shore to shore and from Pole to Pole slowly gave way to grasslands, a habitat more suited to the cooler and drier weather. But that hardiness came with less nutrition. Plant-eating animals had to adapt in order to survive. Horses evolved stronger, enamel-protected teeth and flourished. So too did ruminants such as bison, camels, sheep, and giraffes, whose compartmentalized stomachs are well adapted to digesting grass. Many of the grazers were quick and roamed in herds—new tricks for survival out in the open. Their predators were also forced to adapt.
In the oceans, a new type of large brown algae, called kelp, latched onto rocks and corals in cool shallow waters, establishing a new habitat favored by sea otters and dugongs, a marine mammal related to the elephant. Sharks grew and dominated the seas once again. Megalodon, the biggest shark of all, was nearly 50 feet (15 meters) long.
Meanwhile on land, Asian and African apes diverged and then, several million years later, hominins split from their closest African ape ancestors, the chimpanzees. Adapted to two-footed walking, early hominins dropped out of the trees and started to carry food and tools in their hands. These new species were poised to alter the planet unlike any other in the centuries to come.
Species Spread Out
The continental connections gave animals that had evolved in isolation access to new lands. Elephants and apes wandered from Africa to Eurasia. Rabbits, pigs, saber-toothed cats, and rhinos went to Africa. Elephants and rhinos continued across the Bering Strait to North America. Horses went the other way. Ground sloths migrated from South America to North America; raccoons scurried south. Even rodents may have hopped Pacific islands en route to Australia from Southeast Asia.
As the climate changed, many of the great forests that carpeted the continents from shore to shore and from Pole to Pole slowly gave way to grasslands, a habitat more suited to the cooler and drier weather. But that hardiness came with less nutrition. Plant-eating animals had to adapt in order to survive. Horses evolved stronger, enamel-protected teeth and flourished. So too did ruminants such as bison, camels, sheep, and giraffes, whose compartmentalized stomachs are well adapted to digesting grass. Many of the grazers were quick and roamed in herds—new tricks for survival out in the open. Their predators were also forced to adapt.
In the oceans, a new type of large brown algae, called kelp, latched onto rocks and corals in cool shallow waters, establishing a new habitat favored by sea otters and dugongs, a marine mammal related to the elephant. Sharks grew and dominated the seas once again. Megalodon, the biggest shark of all, was nearly 50 feet (15 meters) long.
Meanwhile on land, Asian and African apes diverged and then, several million years later, hominins split from their closest African ape ancestors, the chimpanzees. Adapted to two-footed walking, early hominins dropped out of the trees and started to carry food and tools in their hands. These new species were poised to alter the planet unlike any other in the centuries to come.
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