Aptychophora

Pseudolioceras compactile, copyright Greg Wood.

Belongs within: Ammonitida.
Contains: Grammoceratinae, Spiroceratidae, Phymatoceratidae, Hammatoceratidae, Graphoceratidae, Sonniniidae, Stephanocerataceae, Oppeliidae, Strigoceratidae.

The Aptychophora are a clade within the ammonites characterised by the development of bivalved aptychi, calcified lower jaws that probably functioned as opercula to close the entrance of the shell. Such structures are first known from the lower Toarcian (in the lower Jurassic) among members of the paraphyletic Hildocerataceae. Members of the ‘Hildocerataceae’ possess cornaptychi, with a thin horny outer layer and a thicker mineralised inner layer, and these are probably the plesiomorphic aptychus condition (Engeser & Keupp 2002). Conches of ‘Hildocerataceae’ are typically compressed and keeled, with straight, sigmoidal or falcate ribs (Donovan et al. 1981).

More derived groups developed alternate aptychus morphologies. The Middle Jurassic to Upper Cretaceous Haplocerataceae possessed lamellaptychi, with strong concentric ribs (Engeser & Keupp 2002). Members of the Haplocerataceae had compressed to discoidal shells with ribbing falcoid to falcate or obsolescent (Engeser & Keupp 2002). The mid Jurassic (Bajocian to Oxfordian) Lissoceratidae had smooth or weakly ornamented conches.

Characters (from Engeser & Keupp 2002): Presence of a calcified lower jaw, both halves attached to each other with a weakly calcified or organic fold. Outer surface with growth lines only. Structure simple in primitive forms, more complex in subordinated groups.

<==Aptychophora [Hildocerataceae, Hildoceratinae]
| i. s.: Strigogranulaptychus Schweigert 2000EK02
| `--*S. planulati (Quenstedt 1852) [=Granulaptychus planulati]EK02
| Asaphoceras Spath 1924DCH81
| Diplesioceras Buckman 1920DCH81
|--BouleiceratinaeDCH81
| |--Frechiella Prinz 1904 [incl. Achilleia Renz 1913]DCH81
| |--Paroniceras Bonarelli 1893 [incl. Jacobella Jeannet 1908]DCH81
| |--Leukadiella Renz 1913DCH81
| |--Bouleiceras Thevenin 1906 [incl. Colcanapites Collignon 1958]DCH81
| |--Oxyparoniceras Guex 1974DCH81
| `--Kohaticeras Fatmi & Hölder 1975DCH81
|--ArieticeratinaeDCH81
| |--Seguenziceras Levi 1896 (see below for synonymy)DCH81
| |--Arctomercaticeras Repin 1968DCH81
| |--Leptaleoceras Buckman 1918DCH81
| |--Canavaria Gemmellaro 1886 [incl. Tauromenia Fucini 1931 non Seguenza 1885, Tauromeniceras Mouterde 1967]DCH81
| |--Neoemaciaticeras Cantaluppi 1970DCH81
| |--Emaciaticeras Funcini 1931 [incl. Seguentia Fucini 1931, Ugdulenia Cantaluppi 1970]DCH81
| |--Fontanelliceras Fucini 1931DCH81
| `--Fieldingia Cantaluppi 1970 (n. d.)DCH81
|--HarpoceratinaeDCH81
| |--Polyplectus Buckman 1890 [incl. Micropolyplectus Guex 1973]DCH81
| |--Fuciniceras Haas 1913 [incl. Eofuciniceras Cantaluppi 1970, Neofuciniceras Cantaluppi 1970]DCH81
| |--Tiltoniceras Buckman 1913 [incl. Pacificeras Repin 1970]DCH81
| |--Lioceratoides Spath 1919 (see below for synonymy)DCH81
| |--Taffertia Guex 1973DCH81
| |--Ovaticeras Buckman 1918DCH81
| |--Whitbyiceras Buckman 1913DCH81
| |--Pseudopolyplectus Mattei 1969DCH81
| |--Sphenarpites Spath 1936DCH81
| |--Eleganticeras Buckman 1913 (see below for synonymy)DCH81
| | `--E. elegantulumC81
| |--Harpoceras Waagen 1869 (see below for synonymy)DCH81
| | |--H. exaratum [incl. Monestieria errata]DCH81
| | `--H. falciferumB93
| |--Protogrammoceras Spath 1913 (see below for synonymy)DCH81
| | |--P. hungaricum Geczy 1976C81
| | |--P. mellahenseP93
| | `--P. praecurionii Geczy 1976C81
| `--Pseudolioceras Buckman 1889EK02 (see below for synonymy)
| |--P. beyrichiW81
| |--P. compactileWK81
| |--P. costistriatumW81
| |--P. crassifalcata [=Canavarella crassifalcata]W81
| |--P. mclintockiW81
| | |--P. m. mclintockiW81
| | `--P. m. fastigatumW81
| |--‘Tugurites’ tugurensisDCH81
| `--P. whiteavesi (White 1889)DCH81 (see below for synonymy)
`--+--HildoceratinaeDCH81
| |--Mercaticeras Buckman 1913DCH81
| |--Parahildaites Blaison 1967DCH81
| |--Renziceras Arkell 1951DCH81
| |--Hildoceras Hyatt 1867 (see below for synonymy)DCH81
| | `--H. bifronsP93
| `--Hildaites Buckman 1921 (see below for synonymy)DCH81
| `--H. levisoni [=Hildoceras (Hildaites) levisoni]L81
|--+--GrammoceratinaeDCH81
| |--+--SpiroceratidaeDCH81
| | `--Tmetoceras Buckman 1892 [incl. Tmetoites Westermann 1964; Tmetoceratinae]DCH81
| | |--‘Helicoceras’ alpinum Thalmann 1923DCH81
| | `--T. scissumWK81
| `--LeioceratinaeDCH81
| |--Canavarella Buckman 1904 [incl. Costiceras Contini 1969, Geyerina Buckman 1913]DCH81
| |--Cylicoceras Buckman 1899 [=Cyclicoceras (l. c.)]DCH81
| |--Staufenia Pompeckj 1906DCH81
| `--Leioceras Hyatt 1867 [incl. Ancolioceras Buckman 1899, Cypholioceras Buckman 1899]DCH81
| |--L. comptumW81
| `--L. opalinumM79
`--+--PhymatoceratidaeP93
`--+--HammatoceratidaeDCH81
|--GraphoceratidaeDCH81
|--SonniniidaeDCH81
|--StephanocerataceaeDCH81
`--HaplocerataceaeDCH81
| i. s.: Tropitoides Spath 1925WCH96
| `--*T. obesus (Stoliczka 1865) [=Ammonites obesus]WCH96
|--OppeliidaeEK02
|--StrigoceratidaeEK02
`--LissocerasP93 [incl. Microlissoceras Sturani 1971DCH81; LissoceratidaeP93]
|--L. (Lissoceratoides) eratoP93
`--L. semicostulatumP93

Eleganticeras Buckman 1913 [incl. Elegantuliceras Buckman 1913, Leptarpites Repin 1970, Ochotoceras Repin 1970]DCH81

Harpoceras Waagen 1869 [=Falcifericeras Breistroffer 1949; incl. Glyptarpites Buckman 1927, Harpoceratoides Buckman 1909, Kolymoceras Dagis 1970, Maconiceras Buckman 1926, Phaularpites Buckman 1928, Tardarpoceras Buckman 1927]DCH81

Hildaites Buckman 1921 [incl. Harpohildoceras Repin 1970, Hildoceratoides Buckman 1921, Murleyiceras Buckman 1921]DCH81

Hildoceras Hyatt 1867 [incl. Goniohildoceras Seguenza 1886, Orthildaites Buckman 1923, Urkutites Géczy 1967]DCH81

Lioceratoides Spath 1919 [incl. Nagatoceras Matsumoto 1947, Neolioceratoides Cantaluppi 1970, Platyharpites Buckman 1927, Praelioceras Fucini 1929]DCH81

Protogrammoceras Spath 1913 [=Bassaniceras Fucini 1929; incl. Argutarpites Buckman 1923, Eoprotogrammoceras Cantaluppi 1970, Neoprotogrammoceras Cantaluppi 1970, Paltarpites Buckman 1922, Wrightia Gemmellaro 1886 non Agassiz 1862]DCH81

Pseudolioceras Buckman 1889EK02 [incl. Buckmanites Guex 1973DCH81, Osperleioceras Krimholz 1963DCH81, Praehaploceras Monestier 1931DCH81, Pseudowalkericeras Maubeuge 1949DCH81, Tugurites Kalacheva & Sey 1970DCH81]

Pseudolioceras whiteavesi (White 1889)DCH81 [=Ammonites whiteavesiDCH81, P. mclintocki whiteavesiW81, *Tugurites whiteavesiDCH81]

Seguenziceras Levi 1896 [=Arieticeras Seguenza 1885 non Quenstedt 1883; incl. Geczya Fantini Sestini 1977, Meneghinia Fucini 1931 non Silvestri 1889, Naxensiceras Fucini 1931 non Checchia-Rispoli 1917, Proarieticeras Cantaluppi 1970, Pseudoarieticeras Cantaluppi 1970, Trinacrioceras Fucini 1931]DCH81

*Type species of generic name indicated

References

[C81] Callomon, J. H. 1981. Dimorphism in ammonoids. In: House, M. R., & J. R. Senior (eds) The Ammonoidea: The evolution, classification, mode of life and geological usefulness of a major fossil group pp. 257–273. Academic Press.

[DCH81] Donovan, D. T., J. H. Callomon & M. K. Howart. 1981. Classification of the Jurassic Ammonitina. In: House, M. R., & J. R. Senior (eds) The Ammonoidea: The evolution, classification, mode of life and geological usefulness of a major fossil group pp. 101–155. Academic Press.

[EK02] Engeser, T., & H. Keupp. 2002. Phylogeny of the aptychi-possessing Neoammonoidea (Aptychophora nov., Cephalopoda). Lethaia 35: 79–96.

[L81] Lehmann, U. 1981. Ammonites jaw apparatus and soft parts. In: House, M. R., & J. R. Senior (eds) The Ammonoidea: The evolution, classification, mode of life and geological usefulness of a major fossil group pp. 275–287. Academic Press.

[M79] Müller, A. H. 1979. Fossilization (taphonomy). In: Robison, R. A., & C. Teichert (eds) Treatise on Invertebrate Paleontology pt A. Introduction. Fossilisation (Taphonomy), Biogeography and Biostratigraphy pp. A2–A78. The Geological Society of America, Inc.: Boulder (Colorado), and The University of Kansas: Lawrence (Kansas).

[P93] Page, K. N. 1993. Mollusca: Cephalopoda (Ammonoidea: Phylloceratina, Lytoceratina, Ammonitina and Ancyloceratina). In: Benton, M. J. (ed.) The Fossil Record 2 pp. 213–227. Chapman & Hall: London.

[W81] Westermann, G. E. G. 1981. Ammonite biochronology and biogeography of the circum-Pacific Middle Jurassic. In: House, M. R., & J. R. Senior (eds) The Ammonoidea: The evolution, classification, mode of life and geological usefulness of a major fossil group pp. 459–498. Academic Press.

[WK81] Wiedmann, J., & J. Kullmann. 1981. Ammonoid sutures in ontogeny and phylogeny. In: House, M. R., & J. R. Senior (eds) The Ammonoidea: The evolution, classification, mode of life and geological usefulness of a major fossil group pp. 215–255. Academic Press.

[WCH96] Wright, C. W., J. H. Calloman & M. K. Howarth. 1996. Treatise on Invertebrate Paleontology pt L. Mollusca 4, revised vol. 4. Cretaceous Ammonoidea. The Geological Society of America, Inc.: Boulder (Colorado), and The University of Kansas: Lawrence (Kansas).

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