|mhorn||Дата: Wednesday, 11.11.2009, 11:31 | Сообщение # 1|
|Motchurova-Dekova N., Radulovic V., Metodiev L. (2009) SHELL MICROSTRUCTURE USED TO UNVEIL |
HOMOEOMORPHY IN RHYNCHONELLIDE BRACHIOPODS. PSEUDOCAPILLIRHYNCHIA PLATONI – NEW EARLY-MIDDLE JURASSIC GENUS AND SPECIES FROM BULGARIA // Comptes rendus de l’Academie bulgare des Sciences. Tome 62, No 10. p.1299-1310.
An interesting case of external homoeomorphy in Early-Middle Jurassic rhynchonellide brachiopods from the Bukorovtsi Member of the Ozirovo Formation (section Dobravitsa-1, W Balkan Mts, Bulgaria) is revealed using shell microstructure as a first diagnostic method, chronologically applied before serial sectioning of a new taxon in order to study its internal morphology. A new genus and species Pseudocapillirhynchia platoni is erected based on coarse fibrous (eurinoid) shell microstructure and subfalciform crura. Because of these primary diagnostic characters, the new genus is placed in the rhynchonellide superfamily Pugnacoidea Rzhonsnitskaia. The representatives of the new genus were initially mixed in one collection with a taxon that is strongly homoeomorphic externally, Capillirhynchia kardonikensis Kamyschan, which, however, is characterised by raduliform crura and fine fibrous (leptinoid) shell microstructure, placing it in the superfamily Rhynchonelloidea d’Orbigny. After the first case study based on the Upper Cretaceous rhynchonellide Homaletarhynchia Simon and Owen, the erection of Pseudocapillirhynchia is the second example in the taxonomy of rhynchonellide brachiopods when the type of the shell microstructure was used as a first step diagnostic method to distinguish a new genus from an existing one in the case of strong external homoeomorphy. This research is also a good example confirming the hypothesis about the correlation between shell microstructure and type of crura in rhynchonellide brachiopods. The comprehensiveness of the taxonomic work in brachiopods should be encouraged because the taxonomic data are the basis of all subsequent conclusions in a wide range of disciplines such as biostratigraphy, palaeoecology, palaeogeography, palaeoclimatology, and others.
Middle Jurassic - Lower Cretaceous ammonites & aptychi