For my a story I'm writing, I have 3 species that are from the same evolution line; Kitsune's, Tanuki's, and Bakeneko/Nekomatas. All three are familiar in the lines of shapeshifiting animals.
Their most distinctive trait is that they can look like a furry/yiff (i.e. zoomorphic) and a kemonomimi, which is what I'm focusing on for this question.
Which got me wondering, would their be a evolutionary reason and standpoint to have their humanoid forms (let's use a Tanuki for an example) that could shapeshift to go to one extreme to another at the same time at will?
(second picture is from Yagi the Goat, who also made more cute anthro pics)
Edit: Made it sound less confusing. I'm asking how they could transform to look like human to an anthromorphic form of their animals (cat, fox, tanuki), etc.