Rantell, L and Rigby, S (2002) 'The hydrodynamic significance of the graptoloid nema in scandent graptoloids.' Senckenbergiana lethaea, 82 (1). pp. 131-140. ISSN 0037-2110

Official URL: http://doi.org/10.1007/BF03043779


Experiments show that the nema, cauda and virgula had a profound effect on the orientation of scandent graptoloids, acting as trailing stabilisers and enforcing a stable orientation on the rest of the colony. Scandent graptolites with a well developed nema would have encountered water currents sicula first and would have responded to changing current orientation with a rapid change in their own orientation. The efficiency of the nema, cauda or virgula was dependent on its length and width relative to that of the rhabdosome. In general, longer, wider structures had a more pronounced effect on orientation at the expense of a slower response time to changing current orientations. Virgula structures such as vanes and trailing threads may have offered a means of overcoming this compromise, offering a strong orientational control and a rapid response time.

Item Type: Article
Keywords: graptolites, hydrodynamics, lower Palaeozoic
Divisions: Chancelry
Date Deposited: 07 Jan 2018 21:46
Last Modified: 07 Jan 2018 21:46
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