Question regarding new skeleton pet

Hi there i just today got the skeleton pet. I wanted to upgrade it to Tier3 so i did. But after upgrade its now desert fox. Is this supposed to happend and/or is there a way to get skeleton appearance back again?

 

wdym you upgraded your pets tier? breed it?

 

You combine two pets to get higher tier pet

 

What pet did you combine it with?

 

Apparently, it should have been the fox
To the TS: there's an option "appearance" when exchanging pets, there you choose what looks the new pet should inherit if the pets are completely different (two dogs will give another dog, obviously). If this choice is not made explicitly, then it's random. I used the skeleton to upgrade my hedgehog (as both are in the "limited" category) and chose to retain the hedgehog appearance, otherwise, I could have gotten a skeleton with hedgehog skills. There's a "Pet appearance change coupon" in the pearl store, though I'm not sure if it can be used to return the skeleton appearance back after pet exchange.