A proper UE4 skeleton, with all 67 bones and a single root bone.
"Game Engine" skeleton might be "UE4-compliant", but it most certainly isn't "UE4-working". It can be imported, sure, but to say the results are hilarious would be a massive understatement:
Also, a comparison between the two skeletons, to show just how different even the basic structure is:
I did find this, but it seems to be no different than "game engine" skeleton.