The use of genetics and the resultant rise of cladistics has revolutionized taxonomy.
Shoebills, for examples, aren't really storks. They have now been moved to Pelecaniformes in a clade with the pelicans. Bitterns, ibises, and herons have also been moved over to Pelecaniformes, although to another clade. All this was fairly recent, like in the last 10-20 years.
Interestingly, new world vultures used to be in Pelecaniformes. Then, DNA data led them to be placed in their own order, Carthartiformes. Now, taxonomists place them in Acciptriformes, with the eagles and hawks.
Isn't science grand?