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Skeletal microstructure and mode of attachment in Palaeacis species (Anthozoa: Tabulata) from the Mississippian and Pennsylvanian of northeastern Oklahoma and northwestern Arkansas

Published online by Cambridge University Press:  20 May 2016

Gregory E. Webb
Gregory E. Webb*
Affiliation:
Department of Geology, Texas A&M University, College Station 77843
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Abstract

Three species of the Paleozoic coral Palaeacis are described from northeastern Oklahoma and northwestern Arkansas. Included are the Chesterian species P. carinata Girty and P. snideri n. nom., a replacement name for the junior homonym P. cuneata Snider, and the Desmoinesian? species P. erecta n. sp. Coralla of each species exhibit two types of microstructure that characterize two skeletal zones. The outer skeletal zone is composed of numerous parallel trabeculae, mostly between 0.2 and 0.3 mm in diameter, that lie perpendicular to, and have their accretionary surfaces on, the exterior surface of the corallum. Trabeculae are closely spaced laterally and are not organized into rows except uncommonly on the distal portion of some coralla. Where trabeculae coalesce into parallel rows, ornamentation on the corallum exterior consists of parallel ridges or rows of small nodes. Where trabeculae are irregularly arranged, external ornamentation consists of irregularly disposed nodes. The inner skeletal zone consists of radially fibrous stereoplasm arranged into discrete septal spines that coalesce into irregularly developed septal ridges in each calice. In P. erecta, septal spines merge into continuous layers of fibro-normal stereoplasm in some places. On the basis of microstructure, corallum morphology, and external ornamentation P. carinata and P. snideri can be allied with P. axinoides Smyth and P. robusta Webb. Palaeacis erecta falls within the same group on the basis of microstructure and ornament, but has a unique corallum morphology.

Two distinct types of skeletal attachment occur in these Palaeacis species. Palaeacis carinata and P. snideri exhibit an encrusting attachment surface that results in a prostrate growth habit wherein smaller substrates were entirely engulfed, producing free-living coralla. Palaeacis erecta exhibits a small, circular attachment surface and an erect growth habit wherein most skeletal accretion occurs perpendicular to, and away from, the substrate. The substrate is not engulfed and the corallum remains attached and sessile throughout astogeny. Palaeacis erecta is, to date, the only Palaeacis species known to possess this erect, sessile growth form.

Type
Research Article
Information
Journal of Paleontology , Volume 67 , Issue 2 , March 1993 , pp. 167 - 178
Copyright
Copyright © The Paleontological Society 

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References

Bassler, R. S. 1950. Faunal lists and descriptions of Paleozoic corals. Geological Society of America Memoir 44, 315 p.Google Scholar
Chudinova, I. I. 1976. Pervaya nakhodka Palaeacis (Tabulata) kirgone verkhoyan'ya. Paleontologicheski Zhurnal, 1976(3):30–35.Google Scholar
Conkin, J. E., Bratcher, T. M., and Conkin, B. M. 1978. Palaeacis obtusa (Meek and Worthen), 1860, emended: its morphology, ontogeny, and stratigraphic significance. University of Louisville Studies in Paleontology and Stratigraphy, 7, 27 p.Google Scholar
Girty, G. H. 1910. New genera and species of Carboniferous fossils from the Fayetteville shale of Arkansas. New York Academy of Science Annals, 20:189–238.Google Scholar
Huffman, G. G. 1958. Geology of the flanks of the Ozark Uplift. Oklahoma Geological Survey Bulletin 77, 281 p.Google Scholar
ICZN. 1985. International Code of Zoological Nomenclature. International Trust for Zoological Nomenclature (with the British Museum, Natural History, London) and University of California Press, Berkeley, 3rd ed., 338 p.Google Scholar
Jeffords, R. M. 1955. Mississippian corals from New Mexico and a related Pennsylvanian species. University of Kansas Paleontological Contributions, Coelenterata 3, 12 p.Google Scholar
McGugan, A. 1983. First record and a new species of Palaeacis Haime, 1857 from the Mississippian of western Canada. Journal of Paleontology, 57:42–47.Google Scholar
Meek, F. B., and Worthen, A. H. 1860. Descriptions of new Carboniferous fossils from Illinois and other western states. Proceedings of the Academy of Sciences of Philadelphia, 1860:447–448.Google Scholar
Milne-Edwards, H. 1857. Histoire naturelle des coralliaires ou polypes proprement dits. Atlas. Roret, Paris, 11 p.Google Scholar
Milne-Edwards, H., and Haime, J. 1850. A monograph of the British fossil corals. First part: introduction. Palaeontographical Society Monograph, London, 71 p.CrossRefGoogle Scholar
Moore, R. C., and Jeffords, R. M. 1945. Descriptions of Lower Pennsylvanian corals from Texas and adjacent states. University of Texas Publication, 4401:63–208.Google Scholar
Nudds, J. R. 1983. The Carboniferous coral Palaeacis in Ireland. Palaeontology, 26:211–225.Google Scholar
Pilcher, R. C. 1975. Intraspecific variation in Palaeacis, a Carboniferous tabulate coral. Geological Society of America Abstracts with Programs, 7:226.Google Scholar
Plusquellec, Y., Lafuste, J., and Webb, G. E. 1990. Organisation de type tétracoralliaire des rides septales de Palaeacis (Cnidaria, Carbonifère). Lethaia, 23:385–397.Google Scholar
Roemer, C. F. 1883. Lethaea geognostica, Theil 1: Lethaea palaeozoica, Part 2. Schweizerbart, Stuttgart, p. 113–544.Google Scholar
Sando, W. J. 1969. Revision of some of Girty's invertebrate fossils from the Fayetteville Shale (Mississippian) of Arkansas and Oklahoma—corals. U.S. Geological Survey Professional Paper, 606-B:9–14.Google Scholar
Smyth, L. B. 1929. On the structure of Palaeacis . Scientific Proceedings of the Royal Dublin Society, 19:125–138.Google Scholar
Snider, L. C. 1915. The paleontology of the Chester Group in Oklahoma. Oklahoma Geological Survey Bulletin, 24:67–122.Google Scholar
Sutherland, P. K., and Manger, W. L. (eds.). 1977. Mississippian–Pennsylvanian boundary in northeastern Oklahoma and northwestern Arkansas. Oklahoma Geological Survey Guidebook, 18, 185 p.Google Scholar
Tourneur, F. J., Lafuste, J. G., and Plusquellec, Y. 1991. Trachypsammia Gerth 1921: morphology, microstructure and systematic affinities. Abstracts VI. International Symposium on Fossil Cnidaria including Archaeocyatha and Porifera:89.Google Scholar
Webb, G. E. 1989. Skeletal structure and microstructure in Visean Palaeacis from Queensland. Memoir of the Association of Australasian Palaeontologists, 8:199–206.Google Scholar
Webb, G. E. 1990. Lower Carboniferous coral fauna of the Rockhampton Group, east-central Queensland. Memoir of the Association of Australasian Palaeontologists, 10:1–167.Google Scholar