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Ancyloceras
''Ancyloceras'' is an extinct genus of heteromorph ammonites found throughout the world during the Lower Cretaceous, from the Lower Barremian The Barremian is an age in the geologic timescale (or a chronostratigraphic stage) between 129.4 ± 1.5 Ma (million years ago) and 121.4 ± 1.0 Ma). It is a subdivision of the Early Cretaceous Epoch (or Lower Cretaceous Series). It is precede ... epoch until the genus extinction during the Lower Aptian.Sepkoski, JacSepkoski's Online Genus Database – Cephalopoda/ref> Selected species *''Ancyloceras audouli'' Astier, 1851 *''Ancyloceras fallauxi'' Uhlig, 1883 *''Ancyloceras mantelli'' Casey, 1960 *''Ancyloceras matheronianum'' d'Orbigny, 1842 *''Ancyloceras vandenheckii'' Astier, 1851 Description ''Ancyloceras'' ammonites have a shell reaching a length of about and a width of about . They are known as heteromorph shaped, with a partly uncoiled shell and the aperture directed toward the coiled part. Most ammonites are homomorph, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barremian
The Barremian is an age in the geologic timescale (or a chronostratigraphic stage) between 129.4 ± 1.5 Ma (million years ago) and 121.4 ± 1.0 Ma). It is a subdivision of the Early Cretaceous Epoch (or Lower Cretaceous Series). It is preceded by the Hauterivian and followed by the Aptian Stage.See Gradstein ''et al.'' (2004) or the online geowhen database (link below) Stratigraphic definitions The original type locality for the Barremian Stage is in the vicinity of the village of Barrême, Alpes-de-Haute-Provence, France. Henri Coquand defined the stage and named it in 1873. The base of the Barremian is determined by the first appearance of the ammonites '' Spitidiscus hugii'' and ''Spitidiscus vandeckii''. The end of the Barremian is determined by the geomagnetic reversal at the start of the M0r chronozone, which is biologically near the first appearance of the ammonite '' Paradeshayesites oglanlensis''. Regional equivalents The Barremian falls in the Gallic epoch, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |