Dactylioceratinae

The subfamily Dactylioceratinae comprises early Jurassic ammonite 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.[1]

Dactylioceratinae
Temporal range: Pliensbachian–Toarcian [1]
Dactylioceras commune
Scientific classification
Kingdom: Animalia
Phylum: Mollusca
Class: Cephalopoda
Subclass: †Ammonoidea
Order: †Ammonitida
Family: †Dactylioceratidae
Subfamily: †Dactylioceratinae
Hyatt, 1867
Synonyms
  • Dactyloidae Hyatt, 1867
  • Kedocertinae Dagis, 1968
  • Mesodactylioceratinae Pinna & Levi-Setti, 1971
  • Reynesoceratinae Wiedenmayer, 1977
  • Nodicoeloceratinae Venturi & Ferri, 2001

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.[1]

Taxonomy

Taxonomic composition of this subfamily differs among literature. Well known is taxonomy according to Treatise on Invertebrate Paleontology, which is shown below with addidion of Tokurites, which has not been known in the time, when current edition of Treatise has been published.[1][2]

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 Nodicoeloceras, Collina and some genera, which are by other scholars considered to be synonyms with Nodicoeloceras, Catacoeloceras and Porpoceras. On the other hand, these scientists increase number of dactylioceratine genera by considering Microdactylites and Mucrodactylites as valid.[1][3]

gollark: *aren't -> don't have enough
gollark: It's depriving those who aren't of xenowyrms.
gollark: I'm wondering if taking the AP xenowyrms when I have enough for the raffle already is slightly evil.
gollark: Stupid annoying not-working code...
gollark: (they aren't, I think)

References
  1. M. K. Howarth 2013. Treatise on Invertebrate Paleontology, Part L, Revised, Volume 3B, Chapter 4: Psiloceratoidea, Eoderoceratoidea, Hildoceratoidea.
  2. Yu.S. Repin (2016). "Lower Jurassic ammonite geologic time scale of Northeast Asia". Neftegasovaâ Geologiâ. Teoriâ i Practika. 11 (4): 1–45. doi:10.17353/2070-5379/47_2016.
  3. Kovács, Z. (2014). Toarcian Dactylioceratidae (Ammonitina) from the Gerecse Mts (Hungary). Hantkeniana, 9, 45-77.


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