Best guess, it was exported to FBX using one of the 'third party', reverse-engineered plug-ins. Comes close to Autodesk's proprietary format, but Poser is fussy...

( Honourable exceptions for Mixamo's v2016, Truebones' new 'PMX to FBX' utility and anything 'by/from Maya', which usually behave...)

What you could try is 'zero rotations, zero figure'. Sometimes this re-aligns the strays. 

I'd expect the over-all figure may then be scaled, XYZ translated using the first sub-rig listed.

Applying any supplied textures to your zoo of parts in material room is another matter entirely...