|mhorn||Дата: Saturday, 25.02.2012, 10:52 | Сообщение # 1|
|Baudouin C., Boselli P., Bert D. (2011) The Oppeliidae of the Acanthicum Zone (Upper Kimmeridgian) from Mount Crussol (Ardèche, France): ontogeny, variability and dimorphism of the genera Taramelliceras and Streblites (Ammonoidea) // Revue de Paléobiologie, T.30. no.2. P.619-684. |
The Kimmeridgian outcrops of the Mount Crussol (in Ardèche), already long known for their abundant ammonites, contain many Oppeliidae. The study of the Acanthicum Zone (Upper Kimmeridgian) enables us to conclude that the microconchs of Taramelliceras compsum and Streblites weinlandi correspond in the authors' opinion to forms previously described as Glochiceras (Lingulaticeras) crenosum and Creniceras dentatum. Bot evidences for considering these macro/microconchs within the single species seems to be not a good solution. As authors are writing, their ranges are not coincident. Identity of the innermost whorls cannot be used as a strong evidence, because juveniles of many species of Taramelliceras and all Lingulaticeras are resembling each other. Other problem appear with using the same name for micro- and mcaroconchs of Streblites: dentatum should be used as species name for Streblites, as it has a priority over the wiehlandi. The study of a significant sample from a precise horizon leads to treat both T. compsum and T. pseudoflexuosum as two morphological elements from the same paleobiological species. This is the same for S. weinlandi and S. levipictus, which are morphologically very close. Finally, studying the genera’s variability highlights mechanisms underlying it (heterochrony of the development and “laws” of covariation).
Middle Jurassic - Lower Cretaceous ammonites & aptychi