In 1984, a set of My Little Pony bookmarks were available as Happy Meals toys from McDonald's.
The bookmarks functioned more like a paperclip. They had a clip at the top that could attach to paper or a book, but the pony itself was three-dimensional so it wouldn't fit inside a book.
The ponies were made with the same mold Hasbro used for the Charmkins My Pony Pixie and later the Mommy Charms.
The top of the bookmarks were the same mold and design used to make Charmkins pocket clips.