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.
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| Genus: | Bifericeras Buckman, 1913
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Bifericeras was named by Buckman in 1913 and is found in Europe.
Biostratigraphic significance
editThe 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.
Distribution
editOnly found at Dimmer Camp, Castle Cary, Somerset.[2]
References
edit- Notes
- ^ Sepkoski, Jack (2002). "A compendium of fossil marine animal genera (Cephalopoda entry)". Bulletins of American Paleontology. 363: 1–560. Archived from the original on 2016-02-25. Retrieved 2017-10-18.
- ^ a b "Paleobiology Database - Bifericeras". Retrieved 17 December 2021.
- 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]
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