It looks very real.
There isn't really any compelling reason I can see why it couldn't be real.
It could be fake, granted, but I've seen both real and fake skeletons, and if this one were a fake, it would be a very, very expensive, elaborately done fake.
Why would anyone put that kind of money into something, only to leave it outside to be destroyed by the elements and curious onlookers who might want to take a piece home, sit on it, climb on it, etc.?
