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The morphology and ultrastructure of Brevigraptus quadrithecatus n. gen., n. sp. (Diplograptacea), and Its convergence upon Dicaulograptus hystrix (Bulman)

Published online by Cambridge University Press:  02 September 2016

Charles E. Mitchell
Charles E. Mitchell*
Affiliation:
Department of Geology, State University of New York at Buffalo, Amherst 14226
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Abstract

Rhabdosomes of Brevigraptus quadrithecatus n. gen., n. sp. (Lasiograptinae, Diplograptacea), from the Upper Ordovician Viola Springs Formation of south-central Oklahoma, comprise four fully developed thecae. The sicula and the first two thecae are fully sclerotized. The ultrastructure of the fusellum is unusually dense but is overlaid by a typical diplograptacean bandaged cortex. The third and fourth thecae consist of clathria covered by a cortical sheet. Lacinia are absent. The cortical sheet comprises bandages deposited in a support dominated pattern that matches expectations of the pterobranch model of peridermal secretion. Lists are fusellar derivatives and exhibit traces of fuselli-like growth increments but no continuous fusellum is present. Lists are strongly thickened with cortical tissue. The fabricational pattern employed in list construction reveals the operation of strong historical constraints during the evolutionary reduction of the fusellum.

The thecal form and list architecture of Brevigraptus quadrithecatus are nearly identical to those of Pipiograptus hesperus Whittington. Brevigraptus quadrithecatus possesses a Pattern G astogeny and exhibits several derived astogenetic features that it shares with P. hesperus and Orthoretiolites hami Whittington. Both thecal and astogenetic similarities suggest the new taxon is a member of the Lasiograptinae, and is closely allied to the aforementioned species.

The thecae of B. quadrithecatus exhibit striking similarity with Dicaulograptus hystrix (Bulman). However, both the details of thecal construction and primordial astogeny differ markedly between these species. The thecal similarities appear to be convergent. Accordingly, D. hystrix is probably not closely allied to the Lasiograptinae.

Type
Research Article
Information
Journal of Paleontology , Volume 62 , Issue 3 , May 1988 , pp. 448 - 463
Copyright
Copyright © The Paleontological Society 

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References

Alberstadt, L. P. 1973. Articulate brachiopods of the Viola Formation (Ordovician) in the Arbuckle Mountains, Oklahoma. Oklahoma Geological Survey Bulletin 117:1–90.Google Scholar
Bates, D. E. B. 1987. The construction of graptolite rhabdosomes in the light of ultrastructural studies. Indian Journal of Geology, 59:1–28.Google Scholar
Bates, D. E. B., and Kirk, N. H. 1978. Contrasting modes of construction of retiolite-type rhabdosomes. Acta Palaeontologica Polonica, 22:427–448.Google Scholar
Bates, D. E. B., and Kirk, N. H. 1986. The mode of secretion of graptolite periderm, in normal and retiolite graptolites, p. 221–236. In Hughes, C. P., Rickards, R. B., and Chapman, A. J. (eds.), Paleoecology and Biostratigraphy of Graptolites. Blackwell Scientific Publications, Oxford.Google Scholar
Bergström, S. M., and Mitchell, C. E. 1986. The graptolite correlation of the North American Upper Ordovician standard. Lethaia, 19:247–266.CrossRefGoogle Scholar
Bulman, O. M. B. 1932. On the graptolites prepared by Holm, Pt. I, Certain diprionidian graptolites and their development. Arkiv für Zoologi, 24A(8):1–46.Google Scholar
Bulman, O. M. B. 1945–1947. A monograph of the Caradoc (Balclatchie) graptolites from the limestones in Laggan Burn, Ayrshire. Palaeontographical Society Monographs, 58 p.Google Scholar
Bulman, O. M. B. 1955. Treatise on Invertebrate Paleontology, Pt. V, Graptolithina. Moore, R. C. (ed.). Geological Society of America and University of Kansas Press, Lawrence, 101 p.Google Scholar
Bulman, O. M. B. 1963. The evolution and classification of the Graptoloidea. Quarterly Journal of the Geological Society of London, 119:401–418.Google Scholar
Bulman, O. M. B. 1970. Treatise on Invertebrate Paleontology, Pt. V, Graptolithina. Teichert, C. (ed.). Geological Society of America and University of Kansas Press, Lawrence, 163 p.Google Scholar
Crowther, P. 1981. The fine structure of the graptolite periderm. The Palaeontological Association, Special Papers in Palaeontology, 26, 119 p.Google Scholar
Elles, G. L. 1922. The graptolite faunas of the British Isles. A study in evolution. Proceedings of the Geological Association, 33:168–200.Google Scholar
Elles, G. L., and Wood, E. M. R. 1901–1918. Monograph of British graptolites, Pts. I-XI. Palaeontographical Society Monographs, 539 p.Google Scholar
Finney, S. C. 1980. Thamnograptid, dichograptid and abrograptid graptolites from the Middle Ordovician Athens Shale of Alabama. Journal of Paleontology, 54:1184–1208.Google Scholar
Finney, S. C. 1985. Paired pleural disks in Dicaulograptus cumdiscus n. sp. Lethaia, 18:361–368.Google Scholar
Finney, S. C. 1986. Graptolite biofacies and correlation of eustatic, subsidence, and tectonic events in the Middle and Upper Ordovician of North America. Palaios, 1:435–461.Google Scholar
Fortey, R. A., and Cooper, R. A. 1986. A phylogenetic classification of the graptoloids. Palaeontology, 29:631–654.Google Scholar
Gould, S. J., and Lewontin, R. C. 1979. The spandrels of San Marco and the Panglossian paradigm: a critique of the adaptationist programme. Proceedings of the Royal Society of London, ser. B, 205:581–598.Google Scholar
Lapworth, C. 1873. On an improved classification of the Rhabdophora. Geological Magazine, 10:500–504, 555–560.Google Scholar
Lapworth, C. 1879. On the geological distribution of the Rhabdophora, Pt. I, Historical. Annals and Magazine of Natural History, ser. 5, 3:245–257.Google Scholar
Mitchell, C. E. 1986. Morphometric studies of Climacograptus Hall and the phylogenetic significance of astogeny, p. 119–130. In Rickards, R. B., Hughes, C. P., and Chapman, A. J. (eds.), Paleoecology and Biostratigraphy of Graptolites. Blackwell Scientific, London.Google Scholar
Mitchell, C. E. 1987. Evolution and phylogenetic classification of the Diplograptacea. Palaeontology, 30:353–405.Google Scholar
Mitchell, C. E., and Carle, K. J. 1986. The nematularium of Pseudoclimacograptus scharenbergi (Lapworth) and its secretion. Palaeontology, 29:373–390.Google Scholar
Rickards, R. B., and Bulman, O. M. B. 1965. The development of Lasiograptus harkessi (Nicholson, 1867). Palaeontology, 8:272–280.Google Scholar
Seilacher, A. 1970. Arbeitskonzept zur Konstruktionsmorphologie. Lethaia, 3:393–396.CrossRefGoogle Scholar
Simpson, G. G., Roe, A., and Lewontin, R. C. 1960. Quantitative Zoology. Harcourt, Brace and Co., New York, 440 p.Google Scholar
Skevington, D. 1960. A new variety of Orthoretiolites hami Whittington. Palaeontology, 2:226–235.Google Scholar
Strachan, I. 1974. Further isolated graptolites from the Ordovician of Girvan. Palaeontological Association, Special Papers in Palaeontology, 13:99–106.Google Scholar
Strachan, I. 1976. Relationships within the Archiretiolitinae, p. 210–213. In Kaljo, D. and Koren', T. (eds.), Graptolites and Stratigraphy. Akademiia nauk Estonskoi SSR, Institut geologii, Tallinn, Eesti.Google Scholar
Urbanek, A. 1976. The problem of graptolite affinities in the light of ultrastructural studies on peridermal derivatives in pterobranchs. Acta Palaeontologica Polonica, 21:3–36.Google Scholar
Urbanek, A. 1978. Significance of ultrastructural studies for graptolite research. Acta Palaeontologica Polonica, 23:595–629.Google Scholar
Whittington, H. W. 1954. A new Ordovician graptolite from Oklahoma. Journal of Paleontology, 28:613–621.Google Scholar
Whittington, H. W. 1955. Additional new Ordovician graptolites. Journal of Paleontology, 29:837–851.Google Scholar