The exact evolutionary relationships of Productidae as well as which groups belong to this family have been a matter of extensive debate throughout much of the 20th Century, primarily due to the three genera
Buxtonia,
Pustula and
Juresania (with the debate later expanded to their families and subfamilies) shifting in position repeatedly between phylogenies and classifications. The emphasis on internal versus external characters to determine the systematics of these groups has largely been responsible for this: the original
Treatise on Invertebrate Paleontology published in 1965 placed emphasis on internal characters (including the cardinal process) as diagnostic, whereas the 2000 revision primarily used external features and shell shape, resulting in differing classification of these clades. More recently, Leighton & Maples (2002) conducted multiple
phylogenetic analyses which are strongly in agreement that
Buxtoniinae and
Juresaniinae belong in
Echinoconchidae rather than Productidae, and that Productidae contains only the subfamilies Leioproductinae, Dictyoclostinae and Productinae. In addition, the genus
Setigerites (historically placed in Buxtoniinae) has features of both productids and echinoconchids, potentially being related to the common ancestor of the two families. The
cladogram results of their phylogenetic analyses are displayed in the cladogram below: }} }} }} }} }} }} }} }} }} }} }} }} ==Description==