You can import the following file types via File Motion File Import ....
Supported motion capture file formats
To import a motion capture file:
The Import Files dialog box appears.
Import Files dialog
Import Options dialog for .bvh file format with Merge options
Import Options dialog for .c3d file format with Merge options
Import Options dialog for .fbx file format with Merge options
Import Options dialog for .trc file format with Merge options