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| Byronia robusta (Koz³owski) Mierzejewski, 1986 synonym: Ascosyrinx robustus Koz³owski, 1967 |
| _______________________________________________________________________________________________ | Zak³ad Paleobiologii - Goethe Lab | Graptolite Net | Organic Microfossils | Pogonophora | |
| Diagnosis by Mierzejewski (1986, p. 146): "Scyphothecae varying in height, distally widening, circular in cross-section, unculpured. Scyphorhiza strongly developed, usually in the form of flat-convex disc. Stolons present in colonial forms." Ultrastructure: The SEM studies showed lamellar structure of periderm but they failed to give more detailed data on the structure. Details of ultrastructure appeared easier to trace in the TEM studies on ultrathin sections. Lamellae found in periderm fragments range from 30 to 35 in numbbbber in periderm the total thickness of which euals 10-15 micrometers. Individual lamellae are built of electron-dense, acuatly bent fibres embedded in a matrix of low electron density. The fibre pattern forms a specific image known in the literature as "parabolic pattern" or "Bouligand pattern". Depending on the angle whichperiderm is cut, the ultrastructural image varies. Fibres vary in thickness from 250 to 370 A, and lamellae from. 0.15 to 1.10 micrometers. Some fragments display fibres slightly denser that the basic matter. A sudden pulse with a strong beam of electrons of such prepararions usually results in a markedincrese of contrast. This may be explained by breakage of the basic matter and, possibly, shrinkage of fibres. "The ultrastructure recorded appears identical with some images of chitin-protein complexes. (...)the results of electron microscope studies suggest chitin character of B. robusta periderm." Byronia robusta was originally described under the generic name Ascosyrinx Koz³owski, 1967 and tretaed as an organims with enigmatic systematic position. This was connected with the fact that the type series of this species was comprising incomplete specimens with missing distal parts of scyphothecae which made them somewhat similar to Ascosyrinx tenuis Koz³owski, 1967. Byronia robusta differs from Byronia naumovi Koz³owski, 1967 in stronger development of scyphorhiza. It is not clear wheter or not the differences in ultrastructure of the scyphothecae of the two species are of primary nature and what istheir eventual taxonomic value. Byronia robusta is known from the erratic boulders of Ordovician (?Silurian) age in the area of Poland. Based on Mierzejewski (1986) ____________________________________________ References: Koz³owski, R. 1967. Sur certains fossiles a test organique. - Acta Palaeontologica Polonica 12, 2, 99-137. Mierzejewska, G. & Mierzejewski, P. 1979. Chitin-protein complex in the Ordovician organic microfossil. - Acta Medica Polona 20, 1, 33-34. Mierzejewski, P. 1986. Ultrastructure, taxonomy and affinities of some Ordovician and Silurian organic microfossils. - Palaeontologia Polonica 47, 129-220. |
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| Class Scyphozoa, Subclass Scyphomedusae, Order: ?Coronata, Incertae familiae |
| Byronia robusta (Koz³owski) Mierzejewski from an erratic boulder no. MZ/39, Ustka (Baltic coast), Ordovician or Silurian. Isolated scyphothecae and their fragments. From Mierzejewski. |
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| Byronia robusta (Koz³owski) Mierzejewski TEM micrograph showing "parabolic pattern" of a chitin-protein complex. From Mierzejewska & Mierzejewski. |
| Edited by Zak³ad Paleobiologii - Goethe Lab Warszawa, 2004 Strony internetowe Zak³adu Paleobiologii dedykowane s¹ pamiêci ró¿okrzy¿owców epok minionych. |
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| See also related pages: Genus Byronia Matthew, 1899 Dithecoidea - a taxonomic wastebasket. |