I have to say two dogs. The tail looks strikingly similar to a cats tail but it is WAY to short. A cats tail is like 80%-90% their body length. Look at the real pic of the cat and then back at this pic. Also the hind legs are really slender. Lastly geography has got ya here. As stated, he only big black cats are Jags and leopards, not mountain lions. Sorry but they are not on this continent.
A real black panther is as allusive as Nessy or Bigfoot. Tons of "sightings" but never a capture or a body.