Both these bones share the same parent bone (head). But it doesn't show because there are no vertices assigned to it. I also noticed that one the bones used to move the eyes sometimes gets misplaced as well. The jaw itself doesn't have any animation applied outside of a key set to the rest position.
I tried re-animating the jaw using both quaternion and euler rotations with no change. Any bones which have the errant bone as a parent are also out of position. Screen shot of resulting error when viewed outside of Blender: (jpeg file)Ĭloser examination of the exported skeleton shows that the Y and Z axis appear swapped. This is causing severe distortion in the attached mesh. If you perform an export and then open the exported file in a 3rd party viewing, you will see that the jaw bone is rotated 90 degrees from where it should be. The export options are: Selected Objects, -Z forward/Y up, export Armature only, Apply Modifiers, Baked Anim, NLA Strips.
The error can be reproduced by selecting the armature in Blender and exporting using the fbx exporter. FBX exporter is applying incorrect rotations to some bones in the armature.
