Hostname: page-component-cd9895bd7-lnqnp Total loading time: 0 Render date: 2024-12-26T20:57:59.988Z Has data issue: false hasContentIssue false
  • English
  • Français

Branching geometry and function of multiramous graptoloids

Published online by Cambridge University Press:  08 April 2016

Richard A. Fortey  and
Adrian Bell
Richard A. Fortey
Affiliation:
Department of Palaeontology, British Museum (Natural History), Cromwell Road, London SW7 5BD, England
Adrian Bell
Affiliation:
School of Plant Biology, University College of North Wales, Deiniol Road, Bangor, North Wales
Get access Rights & Permissions [Opens in a new window]

Abstract

We have produced computer simulations of multiramous graptoloids with the intention of defining the rules governing branching strategies and colony form. Close matches between such simulations and real graptolites show that complex rhabdosomes may be produced by the permutation of relatively simple sets of rules. Those designs found in nature produce an efficient and regular distribution of zooids through the area included by an essentially planar rhabdosome. Strikingly geometrical arrays of stipes, such as the Goniograptus and yin/yang patterns, closely approach paradigmatic harvesting arrays. For dichotomously branching anisograptids the evolutionary trend in reduction of “primary stipes” can be explained by the production of larger spreading colonies. Multiramous graptoloids fed during vertical movement through the water column. Changes in a single branching decision may produce considerable changes in rhabdosome morphology, but these are not necessarily of high taxonomic importance; this is proved by a specimen which is a morphological combination of two “genera.” Although primarily under genetic control, certain modifications to colony form were probably the result of inhibitory interaction between adjacent stipes.

Type
Articles
Information
Paleobiology , Volume 13 , Issue 1 , Winter 1987 , pp. 1 - 19
Copyright
Copyright © The Paleontological Society 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Literature Cited

Bell, A. D. 1986. The simulation of branching patterns in modular organisms. Phil. Trans. R. Soc. London. 313:143–160.Google Scholar
Bell, A. D., Roberts, D., and Smith, A. 1979. Branching patterns: the simulation of plant architecture. J. Theor. Biol. 81:351–375.Google Scholar
Bouček, B. 1933. Monographie der obersilurischen Graptoliten aus der Familie Cyrtograptidae. Geol.-Paleontol. Ustavu Karlovy Univ. Praze. 1:1–84.Google Scholar
Bulman, O. M. B. 1950. Graptolites from the Dictyonema Shales of Quebec. J. Geol. Soc. London. 106:63–99.Google Scholar
Bulman, O. M. B. 1964. Lower Palaeozoic plankton. J. Geol. Soc. London. 120:455–476.Google Scholar
Bulman, O. M. B. 1970. Treatise on Invertebrate Paleontology. Pt. V (rev.). xxxii + 163 pp. Geol. Soc. Am. and Univ. Kansas Press; Lawrence.Google Scholar
Cheetham, A. H. and Thomsen, E. 1981. Functional morphology of arborescent animals: strength and design of cheilostome bryozoan skeletons. Paleobiology. 7:355–383.Google Scholar
Cheetham, A. H. and Hayek, L.-A. C. 1983. Geometric consequences of branching growth in adeoniform Bryozoa. Paleobiology. 9:240–260.Google Scholar
Cooper, R. A. 1979. Ordovician geology and graptolite faunas of the Aorangi Mine area, north-west Nelson, New Zealand. New Zealand Geol. Surv. Paleontol. Bull. 47:1–127.Google Scholar
Cooper, R. A. 1985. Colony design, evolution and classification of the Graptoloidea. Pp. 31–33. In: Extended Abstracts, Hornibrook Symposium, Depart. Scient. Indust. Res., New Zealand.Google Scholar
Cooper, R. A. and Fortey, R. A. 1982. The Ordovician graptolites of Spitsbergen. Bull. Br. Mus. Nat. Hist. Geol. 36:157–302.Google Scholar
Cooper, R. A. and Fortey, R. A. 1983. Development of the graptoloid rhabdosome. Alcheringa. 7:201–221.Google Scholar
Cooper, R. A. and Stewart, I. R. 1979. The Tremadoc graptolite sequence at Lancefield, Victoria. Palaeontology. 22:767–798.Google Scholar
Cowen, R. 1981. Crinoid arms and banana plantations: an economic harvesting analogy. Paleobiology. 7:332–343.Google Scholar
Elles, G. L. and Wood, E. M. R. 1903. A monograph of British graptolites, Part 3, 103–134, pls. 14–19. Palaeontogr. Soc. Monogr.; London.Google Scholar
Erdtmann, B.-D. 1982. A reorganisation and proposed phylogenetic classification of planktic Tremadoc (Early Ordovician) dendroid graptolites. Norsk Geol. Tiddskr. 62:121–144.Google Scholar
Finney, S. C. 1985. Nemagraptid graptolites from the Middle Ordovician Athens Shale, Alabama. J. Paleontol. 59:1100–1137.Google Scholar
Fortey, R. A. 1982. Graptolites. In: Fortey, R. A., Landing, E., and Skevington, D.Cambrian-Ordovician boundary sections in the Cow Head Group, western Newfoundland. Pp. 95–129. In: Bassett, M. G. and Dean, W. T., eds. The Cambrian Ordovician Boundary …. National Museum of Wales; Cardiff.Google Scholar
Fortey, R. A. 1983. Geometrical constraints in the construction of graptolite stipes. Paleobiology. 9:116–125.Google Scholar
Fortey, R. A. and Cooper, R. A. 1986. A phylogenetic classification of the graptoloids. Palaeontology. 29:631–654.Google Scholar
Gardiner, A. R. and Taylor, P. D. 1982. Computer modelling of branching growth in the bryozoan Stomatopora. N. Jb. Geol. Paläontol. Abh. 163:389–416.Google Scholar
Harris, W. J. and Keble, R. A. 1932. Victorian graptolite zones with correlation and description of species. Proc. Roy. Soc. Victoria. 44:25–48.Google Scholar
Harris, W. J. and Thomas, D. E. 1939. Victorian graptolites, Part VI. Some multiramous forms. Mining and Geol. J. 2:55–60.Google Scholar
Huo, Shi-Cheng, Li-Pu, Fu, and De-Gan, Shu. 1986 A mathematical study of the Cyrtograptus sakmarikus lineage with discussions of the evolutionary trends in this lineage. Pp. 197–205. In: Hughes, C. P. and Rickards, R. B., eds. Palaeoecology and Biostratigraphy of graptolites. Geol. Soc. London Spec. Pub:20.Google Scholar
Kirk, N. 1969. Some thoughts on the ecology, mode of life, and evolution of the Graptolithina. Proc. Geol. Soc. London. 1659:273–292.Google Scholar
Lester, S. M. 1985. Cephalodiscus sp. (Hemichordata: Pterobranchia): observations of functional morphology, behavior and occurrence in shallow water around Bermuda. Marine Biol. 85:263–268.Google Scholar
Mackie, G. O. 1986. From aggregates to integrates: physiological aspects of modularity in colonial animals. Phil. Trans. R. Soc. London, B. 313:175–196.Google Scholar
Ng, F. S. P. 1977. Shyness in trees. Nat. Malaysiana. 2:34–37.Google Scholar
Owens, R. M., Fortey, R. A., Cope, J. C. W., Rushton, A. W. A., and Bassett, M. G. 1982. Tremadoc faunas from the Carmarthen District, South Wales. Geol. Mag. 119:1–38.Google Scholar
Ruedemann, R. 1947. Graptolites of North America. Geol. Soc. Am. Mem. 19:1–652.Google Scholar
Seilacher, A. 1970. Arbeitskonzept zur Konstructions-Morphologie. Lethaia. 3:393–396.Google Scholar
Thorsteinsson, R. 1955. The mode of cladial generation in Cyrtograptus. Geol. Mag. 92:37–49.Google Scholar
Urbanek, A. 1973. Organisation and evolution of graptolite colonies. In: Board man, R. S. et al., eds. Animal Colonies: Their Development and Function through Time. Dowden, Hutchinson & Ross; New York.Google Scholar