Portal was the first Valve-developed game to be added to the OS X-compatible list of games available on the launch of the Steam client for Mac on May 12, 2010, supporting Steam Play, in which players that had bought the game either on a Macintosh or Windows computer could also play it on the alternate system.
1 Eurasian Pleistocene megafauna became extinct in roughly same time period despite having a much longer time to adapt to hunting pressure by humans. 2  However, the extinction of the Eurasian megafauna can be viewed as a result of a different process than that of the American megafauna.
Woolly Mammoth Fossils. PLEISTOCENE PERIOD: 250,000 - 10,000 years ago. Emerging 55 million years ago, the group of mammals called Proboscideans are identified by the presence of tusks and a trunk and include mammoths, mastodons and elephants.t is believed that the end of the last Ice Age and the warming of the Earth caused the Woolly mammoths to die out at the end of the Pleistocene Period. The DNA of an extinct wooly mammoth is 95% identical to an Indian elephant.