I don't think you'll find one -- you're looking in the wrong place. Aperture is a photographer's toolset for creating and managing a non-destructive workflow from files created by digital cameras to publishable pictures. GIFs -- and especially animated GIFs -- are graphics entities that have little or nothing to do with photography or with files created by digital cameras.
Here is one of the things Apple says about its product:
Aperture is a professional photography application that lets you refine images, showcase your photography, and manage massive photo libraries.
I know that's the answer, I've heard it before, but Aperture caters for GIFs and so it should cater for more than just the static variety. I think Aperture's evolving to be more than just a a pro photo app, I think it's more of a media app now, look, it accepts PDFs but what have they got to do with photgraphy?
*note: once PDFs are imported their subsequent pages cannot be viewed, which is a similar issue*
*note: once PDFs are imported their subsequent pages cannot be viewed, which is a similar issue
Not true if you drag a pdf file onto the Aperture icon you will be presented with this window
If you convert the PDF doc into JPG (or TIFF) you'll get one image per page. If you keep it as a PDF then you are limited to seeing the first page (though the entire document is in Aperture).