I'm not saying this is true or false and I agree with needing the evidence but black panthers aren't a stretch since a panther and a mt. lion are the same cat. They are both pumas (puma concolor) that just go by different names in different parts of the world. In Texas a lot of people call them cougars, here we call them Mt. lions yet in other locations they are called panthers. They also can have color phases ranging from light tan to a very dark brown or even grey and depending on distance and lighting conditions they can even appear black. This is simply a trait found in this species of cat.