词条 | Bifericeras |
释义 |
|name = Bifericeras |fossil_range = {{fossil range|Sinemurian|ref=[1]}} |regnum = Animalia |phylum = Mollusca |classis = Cephalopoda |subclassis = Ammonoidea |ordo = Ammonitida |superfamilia = Eoderoceratoidea |familia = Eoderoceratidae |genus = Bifericeras |genus_authority = Buckman, 1913 |subdivision_ranks = Species [2] |subdivision =
}} 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 significanceThe 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. DistributionOnly found at Dimmer Camp, Castle Cary, Somerset.[2] References
1. ^{{cite journal|last=Sepkoski |first=Jack |title=A compendium of fossil marine animal genera (Cephalopoda entry) | journal=Bulletins of American Paleontology |volume=363 |pages=1–560 | year=2002 | url=http://strata.geology.wisc.edu/jack/showgenera.php?taxon=231&rank=class |accessdate=2017-10-18 |deadurl=yes | archiveurl=https://web.archive.org/web/20160225225905/http://strata.geology.wisc.edu/jack/showgenera.php?taxon=231&rank=class | archivedate=2008-05-07 |df= }} 2. ^1 {{cite web | title= Paleobiology Database - Bifericeras |authorlink =| coauthors =| year = | url = http://fossilworks.org/bridge.pl?a=taxonInfo&taxon_no=14624 | accessdate = 2014-05-28 }}
3 : Jurassic ammonites|Early Jurassic ammonites of Europe|Fossil taxa described in 1913 |
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