After Clarkson, 1998 [based on House, 1988], Nied´zwiedzki, Salamon & Boczarowski, 2001, Hsiung, 2002- [“Les Fossiles”] and Work & Boardman, 2003

This is not for a long way a perfect presentation of diversity and sheer numbers of Ammonitid taxons. If any one has additional material and phylogeny and species... Please contact me... I simply don't have time to cypher out all of them... :-[

<==o †Ammonitida Zittel, 1884 (aito-ammoniitit; Ammonites)
   |--o †Psiloceratoidea [Psilocerataceae]
   |  |--o †Psiloceratidae
   |  |  |-- †Psiloceras
   |  |  `-- †Alsatites
   |  |--o Schlotheimiidae
   |  |  |-- †Schlotheimia
   |  |  `-- †Sulciferites
   |  |--o †Arietitidae
   |  |  |-- †Arietites
   |  |  |-- †Vermiceras
   |  |  |-- †Arnioceras
   |  |  `-- †Asteroceras
   |  |--o Oxynoticeratidae
   |  |  `--  †Oxynoticeras
   |  `--o Echioceratidae
   |     `-- †Echioceras
   `--+--o †Eoderoceratoidea [Eoderocerataceae]
      |  |--o †Eoderoceratidae
      |  |  |-- †Bifericeras
      |  |  `-- †Coeloceras
      |  |--o †Polymorphitidae
      |  |  |-- †Uptonia
      |  |  `-- †Tropidoceras
      |  |--o †Liparoceratidae
      |  |  |-- †Becheiceras
      |  |  |-- †Cymbites
      |  |  `-- †Andogynoceras
      |  |--o †Amaltheidae
      |  |  |-- †Amaltheus
      |  |  `-- †Pleuroceras
      |  `--o †Dactylioceratidae
      |     |-- †Prodactylioceras
      |     |-- †Dactylioceras
      |     `-- †Catacoeloceras
      |?-o Spiroceratoidea [Spirocerataceae] [also treated as Lytoceratids]
      |  `-- †Spiroceras
      `--+--o †Hildoceratoidea [Hildocerataceae]
         |  |--o †Hildoceratidae
         |  |  |-- †Hildoceras
         |  |  |-- †Harpoceras
         |  |  |-- †Pseudolioceras
         |  |  |-- †Polyplectus
         |  |  |-- †Grammoceras
         |  |  |-- †Pleydellia
         |  |  `-- †Dumortieria
         |  |--o †Graphoceratidae
         |  |  |-- †Leioceras
         |  |  |-- †Staufenia
         |  |  `-- †Ludwigia
         |  |--o †Hammatoceratidae
         |  |  |-- †Haugia
         |  |  `-- †Hammatoceras
         |  `--o †Sonniniidae
         |     `-- †Sonninia
         |--+--o †Stephanocerataceae
         |  |  |--o †Otoitidae
         |  |  |  |-- †Otoites
         |  |  |  `-- †Normannites
         |  |  |--o †Stephanoceratidae
         |  |  |  `-- †Stephanoceras
         |  |  |--o †Macrocephalitidae
         |  |  |  |-- †Macrocephalites
         |  |  |  `-- †Pleurocephalites
         |  |  |--o †Kosmoceratidae
         |  |  |  |-- †Kepplerites
         |  |  |  |-- †Sigaloceras
         |  |  |  |-- †Kosmoceras
         |  |  |  `-- †Gulielmites
         |  |  `--o †Cardioceratidae
         |  |     |-- †Cadoceras
         |  |     |-- †Quenstedtoceras
         |  |     |-- †Lamberticeras
         |  |     |-- †Cardioceras
         |  |     `-- †Amoeboceras
         |  `--o †Perisphinctoidea [Perisphinctaceae]
         |     |--o †Parkinsoniidae
         |     |  |-- †Strenoceras
         |     |  |-- †Garantiana
         |     |  `-- †Parkinsonia
         |     |--o †Tulitidae
         |     |  `-- †Kheraiceras
         |     |--o †Reineckeidae
         |     |  `-- †Reineckeia
         |     |--o †Perisphinctidae
         |     |  |-- †Zigzagiceras
         |     |  |-- †Proplanulites
         |     |  |-- †Grossouvria
         |     |  |-- †Perisphinctes
         |     |  |-- †Orthosphinctes
         |     |  |-- †Ataxioceras
         |     |  |-- †Idoceras
         |     |  |-- †Aulacostephanus
         |     |  |-- †Gravesia
         |     |  |-- †Sutneria
         |     |  `-- †Crussoliceras
         |     |--o †Aspidoceratidae
         |     |  |-- †Peltoceras
         |     |  |-- †Euaspidoceras
         |     |  |-- †Aspidoceras
         |     |  |-- †Physodoceras
         |     |  `-- †Hybonoticeras
         |     |--o †Craspeditidae
         |     |  |-- †Platylenticeras
         |     |  `-- †Tolypeceras
         |     |--o †Olcostephanidae
         |     |  |-- †Olcostephanus
         |     |  `-- †Polyptychites
         |     `--o †Berriasellidae
         |        |-- †Neocomites
         |        |-- †Acanthodiscus
         |        `-- †Saynella
         `--+--o †Haploceratoidea [Haplocerataceae]
            |  |--o †Haploceratidae
            |  |  |-- †Haploceras
            |  |  `-- †Glochiceras
            |  `--o †Oppeliidae
            |     |-- †Oppelia
            |     |-- †Hecticoceras
            |     |-- †Oxycerites
            |     |-- †Brightia
            |     |-- †Ochetoceras
            |     |-- †Taramelliceras
            |     |-- †Creniceras
            |     `-- †Clydoniceras
            `--+--o Desmoceratoidea [Desmocerataceae]
               |  |--o †Desmoceratidae
               |  |  |-- †Barremites
               |  |  |-- †Raspailiceras
               |  |  `-- †Beudanticeras
               |  |--o †Pachydiscidae
               |  |  |-- †Lewesiceras
               |  |  `-- †Pachydiscus
               |  |--o †Pulchelliidae
               |  |  `-- †Nicklesia
               |  `--o †Schloenbachiidae
               |     `-- †Schloenbachia
               |--o Hoplitoidea [Hoplitaceae]
               |  `--o †Hoplitidae [has been treated as Desmoceratoids]
               |     |-- †Hoplites
               |     `-- †Anahoplites
               `--o Acanthoceratoidea de Grossouvre, 1894 [Acanthocerataceae]
                  |--o †Sphenodiscidae Hyatt, 1900
                  |  `--o †Sphenodiscus Meek, 1871
                  |     |-- †S. lenticularis (Owen, 1852) [Ammonites lenticularis Owen, 1852, non Young & Bird, 1828; Ammonites lobata Tuomay, 1856]
                  |     |-- †S. pleurisepta (Conrad, 1857) [Ammonites pleurisepta Conrad, 1857; S. lenticularis (Owen) Kellum, 1962; S. pleurisepta (Conrad) Cobban & Kennedy, 1995; S. pleurisepta (Conrad) Kennedy et al., 1996; S. pleurisepta (Conrad) Landman et al., 2004]
                  |     `-- †S. lobatus (Tuomay, 1856) [Ammonites lenticularis Owen, 1852; Ammonites lobata Tuomay, 1856; S. lobatus (Tuomay) Cobban & Kennedy, 1995; S. lobatus (Tuomay) Kennedy & Cobban, 1996; S. lobatus (Tuomay) Kennedy et al., 1997; S. lobatus (Tuomay) Landman et al., 2004]
                  |--o †Brancoceratidae
                  |  `-- Motoniceras
                  |--o †Lyelliceratidae
                  |  `-- Stoliczkaia
                  |--o †Acanthoceratidae
                  |  |-- †Acanthoceras
                  |  |-- †Mantelliceras
                  |  |-- †Acompsoceras
                  |  |-- †Calycoceras
                  |  `-- †Mammites
                  `--o †Collignoniceratidae
                     |-- †Gauthiericeras
                     `-- †Paratexanites

Reference(s):