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Paired pleural disks in Dicaulograptus cumdiscus n. sp.

Abstract

A diplograptid graptolite with strongly introverted thecae and unusual thecal processes was isolated from limestones of the Ordovician Pratt Ferry Formation of Alabama and is described as a new species Dicaulograptus cumdiscus. The thecal processes are referred to as pleural disks. They occur in pairs above every thecal aperture and are inferred to have functioned as suspension processes receiving uplift from small‐scale turbulent water motion. Such a function is compatible with a passively buoyant mode of life and is difficult to reconcile with an automobile mode of life.

Keywords

  1. Ordovician graptolites
  2. Dicaulograptus
  3. morphology
  4. mode of life

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References

Andres, D. 1980: Feinstrukturen und Vervandschaftsbcziehungen der Graptolithen. Paläont. Zeitschrift 54, 170.
Bulman, O. M. B. 1932: On the graptolites prepared by Holm. I. Arkiv Zoologie 24A (8), 1–46.
Bulman, O. M. B. 1964: Lower Paleozoic plankton. Quarterly Journal Geological Society of London 120, 455–476.
Bulman, O. M. B. 1970: Graptolithina. In Teichert, C. (ed.): Treatise on Invertebrate Paleontology, 2nd ed., Part V, VI‐VI63.
Cooper, G. A. 1956: Chazyan and related brachiopods. Smithsonian Miscellaneous Collections 127, Pt. 1. 1–1024, Pt. 2, 1025–1245.
Crowther, P. R. & Rickards, R. B. 1977: Cortical bandages and the graptolite zooid. Geologica et Palaeontologica 11, 9–46.
Finney, S. 1980: Thamnograptid, dichograptid, and abrograptid graptolites from the Middle Ordovician Athens Shale of Alabama. Journal of Paleontology 54, 1184–1208.
Finney, S. 1984: Biogeography of Ordovician graptolites in the southern Appalachians. In Bruton, D. L. (ed.): Aspects of the Ordovician System. Palaeontological Contributions from the University of Oslo 295, 167–176.
Jaanusson, V. 1960: Graptoloids from the Ontikan and Viruan (Ordov.) limestones of Estonia and Sweden. Bulletin of the Geological Institutions of the University of Uppsala 38, 289–366.
Kirk, N. 1969: Some thoughts on the ecology, mode of life and evolution of the Graptolithina. Proceedings of the Geological Society of London 1659, 273–292.
Kirk, N. 1972: Some thoughts on the construction of the rhabdosome in the Graptolithina, with special reference to extrathecal tissue and its bearing on the theory of automobility. University College of Wales, Aberystwyth, Department of Geology Publications 1, 1–21.
Rickards, R. B. 1975: Palaeoecology of the Graptolithina, an extinct class of the Phylum Hemichordata. Biological Reviews 50, 397–436.
Rickards, R. B. & Bulman, O. M. B. 1965: The development of Lasiograptus harknessi (Nicholson 1867). Palaeontology 8, 272–280.
Ruedemann, R. 1947: Graptolites of North America. Geological Society of America Memoir 19, 1–652.
Schwenke, H. 1971: 5. Water Movement, 5.2 Plants. In Kinne, O. (ed.): Marine Ecology 1, 1091–1121. Wiley‐Interscience.
Sweet, W. & Bergström, S. 1962: Conodonts from the Pratt Ferry Formation (Middle Ordovician) of Alabama. Journal of Palaeontology 36, 1214–1252.
Urbanek, A. 1959: Studies on graptolites II. On the development and structure of graptolite genus Gymnograptus Bulman. Acta Palaeontologica Polonica 4, 279–338.
Urbanek, A. 1966: On the morphology and evolution of the Cucullograptinae (Monograptidae, Graptolithina). Acta Palaeontologica Polonica 11, 291–544.
Urbanek, A. 1978: Significance of ultrastructural studies for graptolite research. Acta Palaeontologica Polonica 23, 595–629.
Urbanek, A. & Towe, K. M. 1975: Ultrastructural studies on graptolites, 2: The periderm and its derivatives in the Graptoloidea. Smithsonian Contributions to Paleobiology 22, 1–24.

Information & Authors

Information

Published In

Volume 18Number 41 October 1985
Pages: 361368

History

Received: 25 September 1984
Published online: 1 October 1985
Issue date: 1 October 1985

Authors

Affiliations

Stanley C. Finney
T. Boone Pickens. Jr. School of Geology, Oklahoma State University, Stillwater, Oklahoma, 74078, U.S.A.;

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Crossref Cited-by

  • Possible propulsion modes in Graptoloidea: a new model for graptoloid locomotion, Paleobiology.
  • The morphology and ultrastructure of Brevigraptus quadrithecatus n. gen., n. sp. (Diplograptacea), and Its convergence upon Dicaulograptus hystrix (Bulman) , Journal of Paleontology.
  • Palaeoecology of the Graptoloidea, Earth-Science Reviews.
  • GRAPTOLITES FROM THE QILANG AND YINGAN FORMATIONS (CARADOC, ORDOVICIAN) OF KALPIN, WESTERN TARIM, XINJIANG, CHINA, Journal of Paleontology.
  • Die Graptolithen des Ordoviziums von Rügen (Norddeutschland, Vorpommern), Paläontologische Zeitschrift.

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