The subfamily Dactylioceratinae comprises early Jurassic

ammonite Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttlefish) ...

genera that lived during Upper Pliensbachian to Upper Toarcian stage. These dactylioceratids existed from Margaritatus ammonite Zone, when they have evolved from Reynesocoeloceratinae and died out in Variabilis Zone without leaving any descendants.

Description

While ribs can be single, they are mostly bifurcating at ventrolateral edge and in some genera, even fibulation (primary ribs are joining at ventrolateral tubercules) can exist. Tubercules might also be present at ventrolateral edge, but not in all species. Final aperture is contracted. Size dimorphism is common.

Taxonomy

Taxonomic composition of this subfamily differs among literature. Well known is taxonomy according to Treatise on Invertebrate Paleontology, which is shown below with addition of ''

Tokurites ''Tokurites'' is a monospecific genus of ammonite that lived during the Toarcian stage of early Jurassic, ammonite zone of Zugodactylites braunianus. Its shell has ribs, which cross the ventral part of the shell creating pricky tubercules there. ...

'', which has not been known in the time, when current edition of Treatise has been published. *''

Reynesoceras ''Reynesoceras'' is genus of ammonites that lived during the upper Pliensbachian stage of early Jurassic. It has evolved from ''Prodactylioceras'', or '' Cetonoceras''. '' Dactylioceras (Eodactylites)'' has probably evolved from this genus. ''Av ...

'' Spath, 1936 *''

Dactylioceras ''Dactylioceras'' was a widespread genus of ammonites from the Lower Jurassic period, approximately 180 million years ago ( mya). Etymology The name ''Dactylioceras'' comes from the Greek ''dactyl'', meaning “finger”, and refers to the shell ...

'' Hyatt, 1867 **''D. (Dactylioceras)'' Hyatt, 1867 **''D. (Orthodactylites)'' Buckman, 1926 **''D. (Iranodactylites)'' Repin, 2000 **''D. (Eodactylites)'' Schmidt-Effing, 1972 *''

Nodicoeloceras ''Nodicoeloceras'' is genus of ammonite that lived during early to middle Toarcian stage of early Jurassic. Members of this genus existed from Exaratum Subzone of Falciferum Zone to Commune subzone of Bifrons Zone. Their fossils were found in Eu ...

'' Buckman, 1926 *''

Peronoceras ''Peronoceras'' is genus of ammonite that lived during the middle Toarcian stage of early Jurassic The Early Jurassic Epoch (geology), Epoch (in chronostratigraphy corresponding to the Lower Jurassic series (stratigraphy), Series) is the earl ...

'' Hyatt, 1867 *''

Zugodactylites ''Zugodactylites'' is an extinct genus of ammonite cephalopod from the lower Toarcian epoch of the Lower Jurassic, ammonite zone Fibulatum. Its fossils are found in Europe, Russia and Canada. Whorl section of shells belonging these ammonites we ...

'' Buckman, 1926 *''

Porpoceras ''Porpoceras'' is genus of ammonite that lived during the early and middle Toarcian stage of early Jurassic. Members of this genus existed from uppermost part of the ''Harpoceras serpentinum'' zone to the '' Haugia variabilis'' zone.Jattiot, R., ...

'' Buckman, 1911 *''

Septimaniceras ''Septimaniceras'' is genus of ammonites that has probably evolved from '' Peronoceras'' and lived during the middle Toarcian stage of early Jurassic The Early Jurassic Epoch (geology), Epoch (in chronostratigraphy corresponding to the Lower J ...

'' Fauré, 2002 *''

Catacoeloceras ''Catacoeloceras'' is a genus of ammonite that lived during Middle Toarcian stage of early Jurassic The Early Jurassic Epoch (geology), Epoch (in chronostratigraphy corresponding to the Lower Jurassic series (stratigraphy), Series) is the earl ...

'' Buckman, 1923 *'' Collina'' Bonarelli, 1893 *''

'' Repin, 2016 Some scholars consider Nodicoeloceratinae as valid taxon and not as synonym of Dactylioceratinae. In their view, some of aforementioned genera does not belong to Dactylioceratinae. These are ''

'', '' Collina'' and some genera, which are by other scholars considered to be synonyms with ''Nodicoeloceras'', ''

'' and ''

''. On the other hand, these scientists increase number of dactylioceratine genera by considering '' Microdactylites'' and ''

Mucrodactylites ''Mucrodactylites'', which is sometimes considered to be a synonym of '' Collina'',M. K. Howarth 2013. Treatise on Invertebrate Paleontology, Part L, Revised, Volume 3B, Chapter 4: Psiloceratoidea, Eoderoceratoidea, Hildoceratoidea. is genus of a ...

'' as valid.Kovács, Z. (2014). Toarcian Dactylioceratidae (Ammonitina) from the Gerecse Mts (Hungary). Hantkeniana, 9, 45-77.

References

Dactylioceratidae Pliensbachian life Toarcian life Pliensbachian first appearances Toarcian extinctions {{ammonitina-stub