Dabashanites mirus Chen, 1979
publication ID |
https://doi.org/ 10.4202/app.00289.2016 |
persistent identifier |
https://treatment.plazi.org/id/03AD87A8-FFDC-6D60-FFF3-FF2966E7855F |
treatment provided by |
Felipe |
scientific name |
Dabashanites mirus Chen, 1979 |
status |
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Fig. 44B View Fig .
Material.—Single phosphatized sclerite SMNH X5792 from sample 1282 (section 2, Fig. 1), upper Nemakit-Daldyn Formation, western Anabar Uplift, Siberia, Russia. Correlated with the upper Fortunian Stage.
Description.—Aggregate (1 mm long and ca. 0.4 mm wide) of closely spaced, hollow, blade-like sclerites that gradually merge along their basal parts. Base of the merged group is rectangular in cross-section. Distal parts of the sclerites are gently curved. Sclerites display inner longitudinal fibrosity and transverse striation on the surface.
Remarks.—Steiner et al. (2004a) synonymized Dabashanites with Siphogonuchites . Dabashanites differs, however, from other siphogonuchitids in being composed of merged sclerites with a common base. Dabashanites may actually be a central branched sclerite of a Siphogonuchites -scleritome. We maintain Dabashanites as a separate taxon until the association of siphogonuchitid sclerites and branched Dabashanites is demonstrated. Dabashanites lemidiensis Kerber, 1988 , from the upper Fortunian–lower part of Cambrian Stage 2 of France probably represents a fragment of a Maikhanella -like scleritome. A certain degree of similarity exists between fused sclerites of Dabashanites and the blind canals that surround the lumen in the sclerites of halkieriid Thambetolepis ( Bengtson et al. 1990) . Ontogenetically merged siphogonuchitid sclerites and cap-like shells composed of merged sclerites support the suggestion that the sclerites and shells may have belonged to the same organism Bengtson 1992).
Stratigraphic and geographic range.— Upper Fortunian Stage of Siberia ( Purella Zone ), South China ( Anabarites trisulcatus – Protohertzina anabarica Assemblage Zone ; see Chen 1979; Steiner et al. 2004a); occurrence in the Paragloborilus subglobosus – Purella squamulosa Assemblage Zone of Meishucunian Stage of South China mentioned by Parkhaev and Demidenko (2010) but may reflect reworking. Also occurs in western Mongolia ( Mongolodus rostriformis and Halkieria amorpha – Tianzhushania tetramera zones; Esakova and Zhegallo 1996), and Iran (Middle Dolomite Member, Soltanieh Formation, Elborz Mountains; Hamdi 1995).
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