The hand holds would have been hard to edit. It could have been a banner they were holding, edited by modern photoshop techniques but even then, it’s very well done.
They didn’t have the ability for special effects back then. They didn’t even have plastics. The creature is beyond a taxidermist skill which would have been the go to person for this sort of thing back then.
It could be a modern hoax, but there are claims the photo’s go back to the 1960’s which is decades before even home computing. They were still using typewriters and TV was a new invention. So if these photos were around in 60’s, it adds to the mystery because they couldn’t have edited it in either.