The predominant patterns recognized with the SEM on the rhabdosome of Dictyonema sp. are almost smooth surfaces or surfaces with faint traces of striation due to a regular arrangement and parallel orientation of the underlying fibrils. However, on some spots specific structures, named rollers, may be recognized. These structures bear close resemblance to the cortical bandages of graptoloid graptolites. The rollers have in fact nothing in common with the cortical bandages. The nature of these structures is obscure. One cannot exclude their post mortem formation due to some non-graptolite organisms and prior to the burial of rhabdosomes in the sediment.
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Source:
Urbanek, A., Mierzejewska, G. and Mierzejewski, P. 1980. - Scanning electron microscopy of sessile graptolites. - Acta Palaeontologica Polonica 25, 2, 197-212. |
