Illustrated breakdown of the bipedal rig (and other) for UE4 ?

Is there a documentation with illustration of breakdown of the bipedal rig for UE4 ? (perhaps vehicle; 4-/6- legged and some flying actor too)

I’d like to make a rig in Blender, which would allow using animations from Marketplace. Importing UE4’s FBX isn’t an option as it seems that FBX importer for Blender is broken. So I would like to knowthe rig structure, naming, hierarchy, and bones’ rolls angles.