Bifericeras

Bifericeras Temporal range: Sinemurian PreЄ Є O S D C P T J K Pg N
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Cephalopoda
Subclass:	Ammonoidea
Order:	Ammonitida
Superfamily:	Eoderocerataceae
Family:	Eoderoceratidae
Genus:	Bifericeras Buckman, 1913
Species
B. annulosum B. bifer B. curvicosta B. juengsti B. nudicosta B. reclinatum B. serpentinum B. soelli B. subplanicosta B. vitreum

Bifericeras is a Lower Jurassic ammonite belonging to the family Eoderoceratidae, and sometimes placed in the subfamily Xipherceratinae. Whorls are strongly depressed, but still evolute in coiling. The early growth state is prolonged, and smooth, followed by a late growth stage with rounded, straight, bituberculate ribs.

Bifericeras was named by Buckman in 1913 and is found in Europe.

Biostratigraphic significance

The International Commission on Stratigraphy (ICS) has assigned the First Appearance Datum of Bifericeras donovani and of genus Apoderoceras the defining biological marker for the start of the Pliensbachian Stage of the Jurassic, 190.8 ± 1.0 million years ago.

References

Notes

Bibliography

• Arkell, et al., 1957. Mesozoic Ammonoidea, in Treatise on Invertebrate Paleontology, (Part L); Geological Soc. of America and University of Kansas press.
• Donovan, D.T. Callomon and Howarth 1981 Classification of the Jurassic Ammonitina; Systematics Association. [1]