Hostname: page-component-78c5997874-lj6df Total loading time: 0 Render date: 2024-11-19T15:29:42.044Z Has data issue: false hasContentIssue false
  • English
  • Français

Worthenopora: an unusual cryptostome (Bryozoa) that looks like a cheilostome

Published online by Cambridge University Press:  20 May 2016

Steven J. Hageman
Steven J. Hageman*
Affiliation:
Department of Geology, University of Illinois, Urbana 61801
Get access Rights & Permissions [Opens in a new window]

Abstract

Worthenopora is a Mississippian cryptostome bryozoan genus with certain characteristics that so closely resemble those of some cheilostomes (Jurassic–Recent) that previous bryozoan experts speculated whether Worthenopora should be assigned to the order Cheilostomata. This raises the question of possible affinities between cryptostomes (class Stenolaemata) and cheilostomes (class Gymnolaemata). Based on wall structure, growth sequence, zooecial shape, and secondary structures such as stylets, Worthenopora is here shown to be a stenolaemate, assignable to the suborder Ptilodictyina with other bifoliate cryptostomes. Although the exterior appearance of Worthenopora superficially resembles some cheilostomes, it represents rather limited divergence from more typical bifoliate growth patterns. Additionally, presence of characteristics such as elongate zooecia with thin exozones, cuticular medial plane, and distinctive exterior ridges justifies retention of the monogeneric family Worthenoporidae. Three species (W. spatulata, W. spinosa, and W. valmeyerensis), known only from North America and primarily restricted to the Illinois Basin, are recognized. Analysis of apertural spacing in these species suggests a trade-off between feeding efficiency and occupation of water-column space. Worthenopora valmeyerensis is considered a hypermorphic derivative of W. spinosa.

Type
Research Article
Information
Journal of Paleontology , Volume 65 , Issue 4 , July 1991 , pp. 648 - 661
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

Astrova, G. G., and Morozova, I. P. 1956. K sistematke mshanok otryada Cryptostomata. Doklady Adademi Nauk SSSR, 110:661–664.Google Scholar
Banta, W. C., McKinney, F. K., and Zimmer, R. L. 1974. Bryozoan monticules: excurrent water outlets? Science, 185:783–784.CrossRefGoogle ScholarPubMed
Bassler, R. S. 1953. Bryozoa, p. G1–G253. In Moore, R. C. (ed.), Treatise on Invertebrate Paleontology, Pt. G. Geological Society of America and University of Kansas Press, Lawrence.Google Scholar
Blake, D. B. 1983. The order Cryptostomata, p. 440–452. In Robinson, R. A. (ed.), Treatise on Invertebrate Paleontology, Pt. G Revised. Geological Society of America and University of Kansas Press, Lawrence.Google Scholar
Boardman, R. S. 1983. General features of the class Stenolaemata, p. 49–137. In Robinson, R. A. (ed.), Treatise on Invertebrate Paleontology, Pt. G, Bryozoa Revised. Geological Society of America and University of Kansas Press, Lawrence.Google Scholar
Borg, F. 1926. Studies on recent cyclostomatous Bryozoa. Zoological Bidrag Uppsala, 10:182–507.Google Scholar
Canu, F., and Bassler, R. S. 1920. North American Early Tertiary Bryozoa. Smithsonian Institution U.S. National Museum Bulletin 106, 163 p.Google Scholar
Cumings, E. R. 1906. Description of the Bryozoa of the Salem Limestone of southern Indiana. Indiana Department of Geology and Natural Resources Annual Report, 30:1274–1296.Google Scholar
Duncan, H. 1949. Genotypes of some Paleozoic Bryozoa. Journal of the Washington Academy of Sciences, 39:122–136.Google ScholarPubMed
Elias, M. K., and Condra, G. E. 1957. Fenestella from the Permian of West Texas. Geological Society of America Memoir 70, 158 p.Google Scholar
Karklins, O. L. 1983. Systematic descriptions for the Suborder Ptilodictyina, p. 489–529. In Robinson, R. A. (ed.), Treatise on Invertebrate Paleontology, Pt. G, Bryozoa Revised. Geological Society of America and University of Kansas Press, Lawrence.Google Scholar
Keys, A. M. 1894. Paleontology of Missouri, Part II. Missouri Geological Survey, V, 260 p.Google Scholar
McKinney, F. K. 1985. Historical record of erect bryozoan growth forms. Geological Society of America, Abstracts with Programs, 18(4):690.Google Scholar
McKinney, F. K. 1986. Historical record of erect bryozoan growth forms. Proceedings of the Royal Society of London, B 228:122–149.Google Scholar
McKinney, F. K., and Kriz, J. 1986. Lower Devonian Fenestrata (Bryozoa) of the Prague Basin, Barrandian Area, Bohemia, Czechoslovakia. Fieldiana Geology, New Series, No. 15, 90 p.Google Scholar
McNamara, K. J. 1986. A guide to the nomenclature of heterochrony. Journal of Paleontology, 60:4–13.Google Scholar
Miller, S. A. 1889. North American Geology and Palaeontology. Western Methodist Book Concern, Cincinnati, Ohio, 664 p.Google Scholar
Owen, D. E. 1966. New Carboniferous Polyzoa from Derbyshire. Geological Journal, 5:135–148.Google Scholar
Pohowsky, R. A. 1973. A Jurassic cheilostome from England, p. 447–461. In Larwood, G. P. (ed.), Living and Fossil Bryozoa, Academic Press, London.Google Scholar
Prout, H. A. 1859. Third series of descriptions of Bryozoa from the Palaeozoic rocks of the western states and territories. Transactions of the Academy of Science of St. Louis, 1:443–452.Google Scholar
Signor, P. W., and Brett, C. E. 1984. The mid-Paleozoic precursor to the Mesozoic marine revolution. Paleobiology, 10:229–245.Google Scholar
Simpson, G. B. 1897. A handbook of the genera of the North American Palaeozoic Bryozoa. Report of the State Geologist of New York, 14:407–608.Google Scholar
Snyder, E. M. 1984. Taxonomy, functional morphology and paleoecology of the Fenestellidae and Polyporidae (Fenestelloidea, Bryozoa) of the Warsaw Formation (Valmeyeran, Mississippian) of the Mississippi Valley. Unpubl. Ph.D. dissertation, University of Illinois, Urbana, 802 p.Google Scholar
Swofford, D. L. 1989. PAUP: Phylogenetic Analysis Using Parsimony, Version 3.0d. David L. Swofford, Champaign, Illinois.Google Scholar
Tavener-Smith, R., and Williams, A. 1972. The secretion and structure of the skeleton of living and fossil Bryozoa. Philosophical Transactions of the Royal Society of London, B 264:97–159.Google Scholar
Thorpe, J. P., and Ryland, J. S. 1987. Some theoretical limitations on the arrangement of zooids in encrusting Bryozoa, p. 227–283. In Ross, J. R. P. (ed.), Bryozoa: Present and Past. Western Washington University Press, Bellingham, Washington.Google Scholar
Ulrich, E. O. 1890. Paleozoic Bryozoa. Illinois Geological Survey, 8:283–688.Google Scholar
Ulrich, E. O. 1893 [1895]. On lower Silurian Bryozoa of Minnesota. Minnesota Geological and Natural History Survey Final Report, 3:96–332.Google Scholar
Vine, G. R. 1884. Fourth report of the committee consisting of Dr. H. C. Sorby and Mr. G. R. Vine, appointed for the purpose of reporting on fossil Bryozoa. British Association for the Advancement of Science, 53rd Meeting, 161–209.Google Scholar
Viskova, L. A., and Morozova, I. P. 1988. Toward a systematic revision of the higher taxa of the phylum Bryozoa. Paleontological Journal, 22:8–18.Google Scholar
Winston, J. E. 1977. Feeding in marine bryozoans, p. 233–271. In Woollacott, R. M. and Zimmer, R. L. (eds.), The Biology of Bryozoans. Academic Press, New York.Google Scholar