Wikipedia notes that North American black panthers may in fact be black cougars, or black jaguars (which is not unthinkable considering how close we are to South America)
Anyone can post anything at Wiki and claim it true - just like a forum. A cougar is a panther in NA - black ones do not and never have existed regardless of how many wish they could. Posting pictures of black deer, or any melanistic animal other then a mountain lion is not proof that a melanistic ml is possible.