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The graptolite nema: problem to all our solutions

Published online by Cambridge University Press:  01 May 2009

R. B. Rickards
R. B. Rickards
Affiliation:
Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK
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Abstract

Lack of understanding of the graptolite nema and virgula is probably the main cause of the general failure to arrive at a general mode of life theory for planktonic species. The nema and virgula are shown to be different structures. The nema may have had a rhabdosome rotational function at early growth stages; the primary function of the virgula may have been rhabdosomal rotation, whilst a secondary function was as a stipe growth guide. Rotational function would be inapplicable for pseudovirgulae and in synrhabdosomes.

Information

Type
Rapid Communication
Information
Geological Magazine , Volume 133 , Issue 3 , May 1996, pp. 343 - 346
Copyright
Copyright © Cambridge University Press 1996

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References

Berry, W. B. N., 1974. Virgula structure and function in a monograptid and orthograptid. Special Papers in Palaeontology 13, 131–40.Google Scholar
Bjerreskov, M., 1976. A new type of graptolite synrhabdosomes. Bulletin of the Geological Society of Denmark 25, 41–7.CrossRefGoogle Scholar
Bjerreskov, M., 1987. Vesicular virgular apparatus in the graptolite Orthograptus calcaratus. Bulletin of the Geological Society of Denmark 35, 115–24.CrossRefGoogle Scholar
Bulman, O.M.B., 1970. Treatise on Invertebrate Paleontology, part V (Revised). Geological Society of America and University of Kansas Press, i –xxxii, V1–V163.Google Scholar
Bulman, O. M. B., & Rickards, R. B., 1966. A Revision of Wiman's Dendroid and Tuboid Graptolites. Bulletin of the Geological Institution of the University of Uppsala 43, 1–72.Google Scholar
Conway, Morris S., 1995. Ecology in deep time. Trends in Ecology and Evolution 10, 290–4.CrossRefGoogle Scholar
Crowther, P. R., 1981. The fine structure of graptolite periderm. Special Papers in Palaeontology 26, 1–119.Google Scholar
Dilly, N., 1993. Cephalodiscus graptoloides sp. nov. a probably extant graptolite. Journal of Zoology 229, 69–78.CrossRefGoogle Scholar
Hutt, J. E., 1974. The development of Clonograptus tenellus and Adelograptus hunnebergensis. Lethaia 7, 79–92.CrossRefGoogle Scholar
Loydell, D. K., & Cave, R., 1994. Pseudovirgular development in the Llandovery graptolite Cochlograptus veles. Geobios 27, 609–13.CrossRefGoogle Scholar
Mitchell, C. E., 1995. An alternative Pterobranch model for secretion of the nema and associated structures in graptolites (abstract). Graptolite News 8, 54–6.Google Scholar
Mitchell, C. E., & Carle, K. J., 1986. The Nematularium of Pseudoclimacograptus scharenbergi (Lapworth) and its secretion. Palaeontology 29, 373–90.Google Scholar
Obut, A. M., & Zaslavskaya, N. M., 1974. Novye dannyye o nachl'-nykh stadiyakh razvitiya retiolitid. In Etyudo po Straftigrafi (ed.Nalivskin, D.V.), pp. 154–62. Moscow: Nauka.Google Scholar
Rickards, R. B., 1974. A combination of pseudovirgulae and lateral branching in a species of dichograptid. Acta Geologica Polonica 24, 231–40.Google Scholar
Rickards, R. B., 1975. Palaeoecology of the Graptolithina, an extinct class of the phylum Hemichordata. Biological Reviews 50, 397–436.CrossRefGoogle Scholar
Rigby, S., 1992. Graptoloid feeding efficiency, rotation, and astogeny. Lethaia 25, 51–68.CrossRefGoogle ScholarPubMed
Rigby, S., & Rickards, R. B., 1989. New evidence for the life habit of graptoloids from physical modelling. Paleobiology 15, 402–13.CrossRefGoogle Scholar
Urbanek, A., & Towe, K. M., 1975. Ultrastructural Studies on Graptolites, 2: The periderm and its derivations in the Graptoloidea. Smithsonian Contributions to Paleobiology 22, 1–24.CrossRefGoogle Scholar
Urbanek, A., Koren', T. N., & Mierzejewski, P., 1982. The fine structure of the virgular apparatus in Cystograptus vesiculosus. Lethaia 15, 207–28.CrossRefGoogle Scholar
Zalasiewicz, J. A., 1984. Dichograptid synrhabdosomes from the Arenig of Britain. Palaeontology 27, 425–9.Google Scholar