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Jurassic Forum » JURASSIC references & paper reviews » Non-Jurassic references » Vašíček Z. (2010) (Aptychi and their significance for taxonomy of ammonites)
Vašíček Z. (2010)
mhornДата: Saturday, 16.10.2010, 13:24 | Сообщение # 1
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Vašíček Z. (2010) Aptychi and their significance for taxonomy of Lower Cretaceous ammonites // Journal of the National Museum (Prague), Natural History Series. T.179. P.183-188.

Pdf: http://www.nm.cz/publika....id=2794

Scarce data on the occurrence of anaptychi and aptychi in shells of Lower Cretaceous ammonites were summarized (including those by Engeser & Keupp, 2002) and compared with the current classification of ammonites. It is suggested that the Haploceratoidea did not survive the Hauterivian (on the base of FAD of lammelaptychi in Late Hauterivian) and, on the base of the new record of anaptychi in the body chamber of Pseudohaploceras, supported the view that the Desmoceratoidea originated from the Phylloceratina. But these conclusions are badly corresponds to the current systematics of the family-level taxa based on the septal suture ontogeny. In opinion of the reviewer Aconeceratidae and other late Haploceratins were derived from Haploceratidae, as follow from their septal suture patterns. Disappearance of the lamellaptychi did not mean disappearance of ammonites to whom they belong, because through the other haploceratin lineages calcite layer in aptychi disappeared sometimes (for example, Lamellaptychus in Oppeliinae followed by Cornaptychus in Hecticoceratinae). Additionally scarcity of data about the aptychi in Perisphinctina suborder (to which desmoceratids belongs) and unknown nature of the aptychi / anaptychi transitions within different lineages (such a transition occurred few times during the history of ammonoids and could be controlled by some environmental factors) lead the reviewer to conclusion that proposed transition from phylloceratids to desmoceratids should be proven independently by other evidences than aptychi. It should be noted that parallel appearance of the same features in non-directly related aptychi has been also described on example of the Middle-Late Jurassic ammonites (Rogov, 2004, Callovian aptychi…).


Middle Jurassic - Lower Cretaceous ammonites & aptychi
 
Jurassic Forum » JURASSIC references & paper reviews » Non-Jurassic references » Vašíček Z. (2010) (Aptychi and their significance for taxonomy of ammonites)
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