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Growth rates of pterobranchs and the lifespan of graptolites

  • Susan Rigby (a1) and P. Noel Dilly (a2)

Abstract

Pterobranchs are the closest living relatives of graptolites. Their skeleton is constructed from the same material, and in a homologous manner. Growth rates of the pterobranch Cephalodiscus gracilis are described for the first time and, along with rhabdopleuran growth rates, they are used to estimate the amount of time invested by a graptolite colony in growing its rhabdosome. This is a measure of minimum age. The significance of age calculations is shown for individuals and large communities of graptoloids. Large individuals can be shown to be much older than the time it would have taken them to settle through seawater and so it is shown that graptoloids moved up, as well as down, through the water column. Life tables constructed for biserial graptoloids from the Utica shale in Quebec, Canada, suggest that these graptoloids died from constant environmental stress. Graptoloid length can thus be a function of environment and should only cautiously be considered to be of taxonomic significance.

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Andres, D. 1980. Feinstrukturen und Verwandschaftsbeziehungen der graptolithen. Paleontologie Zeitschrift 54:129170.
Armstrong, W. G., Dilly, P. N., and Urbanek, A. 1984. Collagen on the pterobranch coenecium and the problem of graptolite affinities. Lethaia 17:145152.
Bulman, O. M. B. 1964. Palaeozoic plankton. Quarterly Journal of the Geological Society of London 120:455476.
Crowther, P. R. 1981. The fine structure of the graptolite periderm. Special Papers in Palaeontology 26.
Dilly, P. N. 1986. Modern pterobranchs: observations on their behaviour and tube building. Pp. 261269In Hughes, C. P. and Rickards, R. B., eds. Palaeoecology and biostratigraphy of graptolites. Geological Society Special Publication 20: 261–269.
Dilly, P. N. 1988. Tube building in Cephalodiscus gracilis. Journal of Zoology (London) 216:465468.
Dilly, P. N. 1992. Cephalodiscus graptolitoides: a living graptolite? Journal of Zoology (London) 229:6978.
Elles, G. L., and Wood, E. M. R. 1901–1918. A monograph of British graptolites. Monograph of the Palaeontological Society.
Finney, S. C. 1979. Mode of life of planktonic graptolites: flotation structure in Ordovician Dicellograptus sp. Paleobiology 5:3139.
Gilmour, T. H. J. 1978. Ciliation and function of the food collecting and waste rejecting organs of lophophorates. Canadian Journal of Zoology 56:21422155.
Hutchinson, G. E. 1978. An introduction to population ecology. Yale University Press, New Haven.
Jorgensen, C. B. 1966. The biology of suspension. Pergamon Press, Oxford.
Kirk, N. H. 1969. Some thoughts on the ecology, mode of life and evolution of the Graptolithina. Proceedings of the Geological Society of London 1659:273292.
Kirk, N. H. 1972. More thoughts on the automobility of graptolites. Journal of the Geological Society of London 128:127133.
Kirk, N. H. 1978. Mode of life of graptolites. Acta Palaeontologica Polonica 23:533555.
Kozlowski, R. 1949. Les graptolithes et quelque nouveaux groupes d'animaux du Tremadoc de la Pologne. Palaeontologica Polonica 3:1235.
Lack, D. 1943. The age of the blackbird. British Birds 36:166175.
Lenz, A. C. 1974. A membrane-bearing Cyrtograptus and an interpretation of the hydrodynamics of the cyrtograptids. Special Papers in Palaeontology 13:205214.
Mitchell, C. E. 1987. Evolution and phylogenetic classification of the Diplograptacea. Palaeontology 30:353405.
Putman, R. J., and Wratten, S. D. 1984. Principles of ecology. Chapman and Hall, London.
Rickards, R. B. 1975. Paleoecology of the Graptolithina, an extinct class of the Phylum Hemichordata. Biological Reviews of the Cambridge Philosophical Society 50:397436.
Rickards, R. B., and Chapman, A. 1991. Bendigonian graptolites (Hemichordata) of Victoria. National Museum of Victoria Memoir Series 52:1135.
Rickards, R. B., and Stait, B. A. 1984. Psigraptus, its classification, evolution and zooid. Alcheringa 8:101111.
Rigby, S. 1991. Feeding strategies in graptoloids. Palaeontology 34:797815.
Rigby, S., and Rickards, R. B. 1989. New evidence for the life habit of graptoloids from physical modelling. Paleobiology 15:402413.
Ryland, J. S. 1971. Bryozoans. Hutchinson University Library, London.
Stebbing, A. R. D. 1970. Aspects of the reproduction and life cycle of Rhabdopleura compacta (Hemichordata). Marine Biology 5:205212.
Sudbury, M. 1991. The dimensions of the graptolite zooid. Geological Magazine 128:381384.
Towe, K. M., and Urbanek, A. 1972. Collagen-like structures in Ordovician graptolite periderm. Nature (London) 237:433445.
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Paleobiology
  • ISSN: 0094-8373
  • EISSN: 1938-5331
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