Nothing as recent as 50k years, but there's this... https://arstechnica.com/science/2018/04/are-we-sure-there-wasnt-a-coal-burning-species-55-million-years-ago

Nothing as recent as 50k years, but there's this... https://arstechnica.com/science/2018/04/are-we-sure-there-wasnt-a-coal-burning-species-55-million-years-ago/ https://arstechnica.com/science/2018/04/are-we-sure-there-wa... I consider it kind of a thought experiment that shows us how little we really know about the extreme distant past. Our planet tens or hundreds of millions of years ago is as faint and remote as distant stars light years away.