Short answers, pulled from the story.
The Neogene is a geologic period spanning 20.45 million years, from the end of the Paleogene to the beginning of the Quaternary Period. It is the second period of the Cenozoic Era and contains two epochs: the Miocene and the Pliocene.
The term "Neogene" was coined in 1853 by Austrian palaeontologist Moritz Hörnes, who lived from 1815 to 1868.
The formation of the Isthmus of Panama late in the Pliocene was the most significant event, connecting North and South America. It cut off warm ocean currents between the Pacific and Atlantic, leaving only the Gulf Stream to transfer heat toward the Arctic.
Homo habilis, the first member of the genus Homo, appeared in Africa near the end of the Neogene period.
The Pliocene Warm Interval lasted from about 5.3 to 2.7 million years ago and interrupted the longer-term cooling trend of the Neogene. It had atmospheric carbon dioxide levels similar to the present day and is often studied as an analogue for projected near-future climate under anthropogenic global warming.
Following the 2008 International Geological Congress in Oslo, Norway, the ICS decided in May 2009 that the Neogene ends at 2.58 million years ago, where the Quaternary Period begins.