Annuloceras

Annuloceras ("Ringed Horns") is an extinct genus of ammonite cephalopod. Its fossils are found in Lower Barremian sediments from California. The genus is currently placed in the family Aegocrioceratidae.[2]

Annuloceras
Temporal range: Barremian[1]
↓
Annuloceras summersi
Scientific classification
Kingdom:
Animalia
Phylum:
Mollusca
Class:
Cephalopoda
Order:
Ammonitida
Suborder:
Ancyloceratina
Superfamily:
Protancyloceratoidea
Family:
Aegocrioceratidae
Genus:
Annuloceras

Murphy et al, 1995
Species
  • A. summersi

Annuloceras is a heteromorph ammonite similar in form to other heteroceratids except that the early helix is more loosely wound. Macroscaphites differs in that the early portion is planispiral and tightly wound. Contemporary Shastoceras, found the same strata in California, differs in lacking a coiled juvenile section.

References
  1. Sepkoski, Jack (2002). "Sepkoski's Online Genus Database". Retrieved 2014-05-28.
  2. Klein, J.; et al. (2007). "Lower Cretaceous Ammonites III Bochianitoidea, Protancyloceratoidea, Ancyloceratoidea, Ptychoceratoidea". Fossilium Catalogus I: Animalia. 144: 1–381.
  • A New Heteromorph Ammonite from the Barremian (Cretaceous) of California Michael A. Murphy, Peter U. Rodda, Patrick Embree Journal of Paleontology, Vol. 69, No. 6 (Nov., 1995), pp. 1179–1182 abstract


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