I was thinking Mountain Lion (to Lion/Tiger shape). And so it seems,.. need to have been seen the beast.. Do it need to be "mundane" beast, or can that shapechange be used to turn into more exotic/magical beings? like hmm.. Pegasus ? (after seeing it first. Pegasi dont have any "superhatural" powers, just horses with wings..)
And, are humans (humanoids) considered viable shape to turn ?