The Pliocene Epoch (meaning "very recent") comprises a relatively short time between 5 and 2 million years ago, and is the last epoch of the Tertiary Period. The Pliocene saw general climatic cooling, with subtropical regions retreating equatorially. During this time, India collided with Asia and gave rise to the Himalaya Mountains.
Significant in the fossil record of the Pliocene are the early hominid remains from Africa. Also, the North American three-toed horse Hipparion crossed the Bering Straits land bridge and entered Asia and Europe, while mastodons reversed the passage and entered the Americas.
Classic Fossil-Bearing Sites
Hemphill Beds, Texas, USA
Lake Turkana, Africa
A 23 km craterform structure about 3.5 million years in age is found in El'gygtgyn, Russia.
The hominid fossil record in Africa begins about 4 million years ago in the Early Pliocene, with representatives of the genus Australopithecus from Ethiopia and Tanzania. The australopithecine "Homo habilis" was one of the later examples, surviving into the Early Pleistocene. Homo erectus arose about one million years ago in the Pleistocene, giving rise to our own genus.
Rise of Isthmus of Panama
South America was isolated from North America from the Late Cretaceous (65 mya) until the late Pliocene, approximately 3 mya. South America, prior to the rise of the isthmus of Panama, was noted for marsupial mammalian fauna, while dominant mammals in the north were placental.
After the connection of the two continents, 16 originally southern genera moved to the north, and 23 originally northern genera moved south. While the effect on North America was negligible, today more than 50% of the genera found in South America are descended from northern species.
Rise of Himalayas
In the Late Tertiary, the Indian subcontinent slammed into Asia, creating the still-rising Himalaya Mountains.