Bifericeras is a Lower Jurassic

Jurassic

The Jurassic is a geologic period and system that extends from about Mya to  Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...

 ammonite beloning to the family Eoderoceratidae

Eoderoceratidae

The Eoderoceratidae is the ancestral and most primitive family of the Eoderocerataceae; lower Jurassic ammonite cephalopods, characterized by evolute, commonly serpenticonic, shells that had long body chambers and would have had no stable floating position; and thus resemble contemporary...

, 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.

References

• 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. http://www.rogov.zwz.ru/Donovan,%20Callomon,%201981_J%20Ammon.PDF