If you are referring to your OMGsr butterfly wolf, its from Christmas 2008;
archive/2008/Christmas/Butterfly%20wolfevery Dec 18th we have a re-release of older rares, so almost every rare from previous years will be available when adopting the advent calendar gifts that day. They won't show up in that year's section of the archive, you have to find where they are from previous years, or every year we have dedicated threads for asking where your Dec 18th pets are in the archives if you don't want to look for them yourself. This pet in particular is quite valuable, so I'd be careful with any trades offered for it, even if they seem like a good offer, its best to get it checked first on the
"is this a fair trade?" thread.
Went ahead and found your other two Dec 18th pets as well;
The bunny is from Easter 2012;
archive/2012/Easter/BunnyThe dog is from March 2010;
archive/2010/March/Dog