The Marsupial Lion , Thylacoleo carnifex , is an extinct species of carnivorous marsupial that lived in Australia from the early to the late Pleistocene , from 1,600,000 to 40,000 years ago . The scientific name comes from the words thylakos - pouch , leo - lion , and carnifex - murderer , tormentor , or butcher . The Marsupial Lion ( Thylacoleo carnifex , the `` murderous ( or ` meat-cutting ' ) marsupial lion '' from thylakos - pouch , leo - lion , carnifex - murderer , tormentor , ` butcher ' ) is an extinct species of carnivorous marsupial mammal that lived in Australia from the early to the late Pleistocene ( 1,600,000 â `` 46,000 years ago ) .