Smilodon Lived in the grasslands and pine forests of North and South America, and was a very fierce hunter. He was like the "T-Rex" of the Pleistocene, feeding upon wooly mammoths, glyptodonts, cavemen, and large bears. Smilodon had an average length of 7-9 feet and stood about 1.2 meters tall. One distinguishing feature which sets Smilodon apart from today's lions is that it could open its jaw 120 degrees while today’s lions can only open their jaw 65 degrees. Smilodon is estimated to have died out approximately 20,000 years ago.