Use the New button to create a new skeleton.

New skeletons appear as two joints and a bone. The first joint is positioned at the origin. Once a skeleton is created, add other bones using the Bone panel (joints are automatically created when bones are added). The new skeleton will appear in the scene list as "mosSkeleton,#". Each skeleton is prefixed with "mos" (MOtionStudio) so that all skeletons are kept together in the scene list (or whenever sorted alphabetically). Remember that you can rename all Motion Studio objects however you like.

The Rebuild Skeleton button can be used to reconstruct all bone and joint objects in the current skeleton in case of emergency. Warning: using this function will erase all animations for the skeleton.