Desmograptus Micronematodes, A Silurian Dendroid Graptolite, And Its Ultrastructure

Kate M. Saunders, Denis E. B. Bates, Joanne Kluessendorf, David K. Loydell, Donald G. Mikulic

Research output: Contribution to journalArticlepeer-review

15 Citations (SciVal)

Abstract

Desmograptus micronematodes from Thornton quarry, Cook County, Illinois, USA, remarkably preserved in relief and encased in pyrite, is described. The internal details of the thecae, and of the stolon system, examined using the SEM, allow the reconstruction of the growth of a stipe. The stolons and stolonal nodes are formed of a dense crassal fabric, and are surrounded by a loose fabric of three-dimensional fibrils. The nodes have a complex structure of three boxes with proximal and distal nozzles. The base of a bitheca, and the base of each autothecal cup, has a central nozzle surrounded by a unique honeycomb fabric. The ultrastructure of the cortical fibrils, with their clockwise striations, is similar to that in Dendrograptus, and may be universal in the graptolites. The nodes of the stolon system appear identical to those of Acanthograptus and other dendroids, but differ from those of the extant hemichordate Rhabdopleura, which have only a diaphragm, and lack box structures.
Original languageEnglish
Pages (from-to)541-559
Number of pages19
JournalPalaeontology
Volume52
Issue number3
Early online date06 Apr 2009
DOIs
Publication statusPublished - May 2009

Keywords

  • autotheca
  • bitheca
  • desmograptus
  • dendroid graptolite
  • stolon
  • ultrastructure

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