Hostname: page-component-cd9895bd7-hc48f Total loading time: 0 Render date: 2024-12-24T06:24:02.442Z Has data issue: false hasContentIssue false

Form of the trilobite digestive system: alimentary structures in Pterocephalia

Published online by Cambridge University Press:  20 May 2016

Brian D. E. Chatterton
Affiliation:
1Department of Geology, University of Alberta, Edmonton T6G 2E3, Canada
Zerina Johanson
Affiliation:
1Department of Geology, University of Alberta, Edmonton T6G 2E3, Canada
George Sutherland
Affiliation:
2Canadian Petroleum Training Institute, P.O. Box 3651, Postal Station B, Calgary, Alberta T2M 4M4, Canada

Abstract

Three types of alimentary canals (=midgut) occur in the Annelida and non-trilobite Arthropoda: 1) a sagittal tube with metamerically paired diverticula related to the number of somites; 2) a tube that is constricted slightly between somites; and 3) a simple tubular gut that may taper slightly backwards to the anus. At least two of these three types (1 and 3) occur in the Trilobita. Pterocephalia and Olenoides share the first type with the probable sister taxon to the Trilobita, Naraoia (Nectaspida), and this is probably the plesiomorphic condition for the class. Varying feeding habits may well have made this character homoplastic within each of these groups. The preservation of parts of the alimentary tract in specimens of Upper Cambrian Pterocephalia n. sp. (McKay Group, British Columbia) was probably a function of taphonomic and/or very early diagenetic changes that resulted from the type of food preferred by that trilobite. Other trilobites from the same beds do not have their soft parts preserved. The alimentary structures are preserved in a different fashion from, apparently unattached to, and an order of magnitude larger than genal caeca that occur in this taxon. Thus, genal caeca are regarded as imprints of circulatory rather than alimentary structures.

Energy dispersive analysis of a fragment of preserved alimentary tract of Pterocephalia n. sp. showed the presence of Ca, Si, Al, Fe, P, K, Na, and Cl. These alimentary tracts are composed of a complex mixture of minerals that probably includes clays, detrital quartz, carbonates, phosphates, and oxides or hydroxides. The structure of these dark fillings is microcrystalline. The presence of detrital minerals as part of this mixture would suggest that this trilobite was a deposit feeder.

Type
Research Article
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

Barker, P. L., and Gibson, R. 1977. Observations of the feeding mechanism, structure of the gut, and digestive physiology of the European lobster Homarus gammarus (L.) (Decapoda: Nephropidae). Journal of Experimental Marine Biology and Ecology, 26:297324.CrossRefGoogle Scholar
Barrande, J. 1852. Système Silurien du Centre de la Bohěme. lère partie, Crustacés, Trilobites. Published by the author, Prague and Paris, 935 p.Google Scholar
Beyrich, E. 1846. Untersuchungen ueber Trilobiten. 2. Stück, 30 p.Google Scholar
Briggs, D. E. G. 1978. The morphology, mode of life, and affinities of Canadaspis perfecta (Crustacea: Phyllocarida), Middle Cambrian, Burgess Shale, British Columbia. Philosophical Transactions of the Royal Society of London, B, 281:439487.Google Scholar
Briggs, D. E. G. 1981. The arthropod Odoraia alata Walcott, Middle Cambrian, Burgess Shale, British Columbia. Philosophical Transactions of the Royal Society of London, B, 291:541582.Google Scholar
Briggs, D. E. G., and Fortey, R. A. 1989. The early radiation and relationships of the major arthropod groups. Science, 246:241243.Google Scholar
Bright, R. C. 1959. A paleoecologic and biometric study of the Middle Cambrian trilobite Elrathia kingii (Meek). Journal of Paleontology, 33:8398.Google Scholar
Bruton, D. L. 1981. The arthropod Sidneyia inexpectans, Middle Cambrian, Burgess Shale, British Columbia. Philosophical Transactions of the Royal Society of London, B, 295:619653.Google Scholar
Bruton, D. L., and Whittington, H. B. 1983. Emeraldella and Leancholia, two arthropods from the Burgess Shale, Middle Cambrian, British Columbia. Philosophical Transactions of the Royal Society of London, B, 300:553582.Google Scholar
Chatterton, B. D. E. 1980. Ontogenetic studies of Middle Ordovician trilobites of the Esbataottine Formation, Mackenzie Mountains, Canada. Palaeontographica, A, 171, 74 p.Google Scholar
Cisne, J. L. 1975. Anatomy of Triarthrus and the relationships of the Trilobita. Fossils and Strata, 4:4563.Google Scholar
Cisne, J. L. 1981. Triarthrus eatoni (Trilobita): anatomy of its exoskeletal, skeletomuscular and digestive systems. Palaeontographica Americana, 9:99142.Google Scholar
Clarke, K. U. 1979. Visceral anatomy and arthropod phylogeny, p. 467549. In Gupta, A. P. (ed.), Arthropod Phylogeny. Van Norstrand Reinhold Company, New York.Google Scholar
Coleman, C. O. 1991. Redescription of Anchiphimedia dorsalis (Crustacea, Amphipoda, Iphemediidae) from the Antarctic, and functional morphology of its mouthparts. Zoologica Scripta, 20:367374.Google Scholar
Emerson, M. J., and Schram, F. R. 1991. Remipedia. Part 2. Paleontology. Proceedings of the San Diego Society of Natural History, 7, 52 p.Google Scholar
Hickman, C. P. 1973. Biology of the Invertebrates. C. V. Mosby Co., St. Louis, 757 p.Google Scholar
Hughes, C. P. 1975. Redescription of Burgessia bella from the Middle Cambrian Burgess Shale, British Columbia. Fossils and Strata 4, 415435.Google Scholar
Jaekel, O. 1901. Beiträge zur Beurtheilung der Trilobiten, Theil 1. Zeitschrift der Deutschen Geologischen Gesellschaft, 53:133171.Google Scholar
Jamieson, B. G. M. 1981. The Ultrastructure of the Oligochaeta. Academic Press, London, 462 p.Google Scholar
Jell, P. A. 1975. Australian Middle Cambrian eodiscoids, with a review of the superfamily. Palaeontographica A, 150, 97 p.Google Scholar
Jell, P. A. 1978. Trilobite respiration and genal caeca. Alcheringa, 2:251260.Google Scholar
Kunze, J. C. 1981. The functional morphology of stomatopod Crustacea. Philosophical Transactions of the Royal Society, B, 292:255328.Google Scholar
Kunze, J. C. 1983. Stomatopoda and evolution of the Hoplocarida, p. 165188. In Schram, F. R. (ed.), Crustacean Phylogeny. Crustacean Issues 1. A. A. Balkema, Rotterdam.Google Scholar
Norford, B. S. 1962. Illustrations of Canadian fossils. Cambrian, Ordovician and Silurian of the Western Cordillera, Geological Survey of Canada Paper 62-14, 25 p.CrossRefGoogle Scholar
Öpik, A. A. 1961. Alimentary caeca of agnostids and other trilobites. Paleontology, 3:410438.Google Scholar
Ramsköld, L., and Edgecombe, G. D. 1991. Trilobite monophyly revisited. Historical Biology, 4:267283.Google Scholar
Raymond, P. E. 1920. The appendages, anatomy and relationships of trilobites. Connecticut Academy of Arts and Sciences, Memoirs, VII, 169 p.CrossRefGoogle Scholar
Rominger, C. 1887. Description of primordial fossils from Mt. Stephens, N.W. Territory of Canada. Proceedings of the Philadelphia Academy of Natural Sciences, 1887:1219.Google Scholar
Schram, F. R. 1983. Remipedia and crustacean phylogeny, p. 2228. In Schram, F. P. (ed.), Crustacean Phylogeny. Crustacean Issues, 1.Google Scholar
Schram, F. R. 1986. Crustacea. Oxford University Press, New York, Oxford, 606 p.Google Scholar
Sekiguchi, K. (ed.). 1988. Biology of Horseshoe Crabs. Science House Company Limited, Tokyo, 428 p.Google Scholar
Sims, R. W., and Gerard, B. M. 1985. Earthworms. Linnaean Society of London and the Estuarine and Brackish-Water Sciences Association, London, 171 p.Google Scholar
Snajdr, M. 1987. Zazívací trakt Deanaspis goldfussi (Barrande). Casopis národního Muzea—radu prírodovedná, 156:816.Google Scholar
Snajdr, M. 1990. Bohemian Trilobites. Geological Survey, Prague, 265 p.Google Scholar
St⊘rmer, L. 1939. Studies on trilobite morphology. Part 1. The thoracic appendages and their phylogenetic significance. Norsk Geologisk Tiddskrift, 19:143273.Google Scholar
St⊘rmer, L. 1959. Trilobitoidea, p. O23O37. In Moore, R. C. (ed.), Treatise on Invertebrate Paleontology, Pt. O, Arthropoda 1. Geological Society of America and University of Kansas Press, Lawrence.Google Scholar
Stürmer, W., and Bergström, J. 1973. New discoveries on trilobites by X-rays. Paläontologisches Zeitschrift, 47:104141.Google Scholar
Walcott, C. D. 1881. The trilobite: new and old evidence relating to its organization. Museum of Comparative Zoology, Harvard College, Bulletin, 8(10):191224.Google Scholar
Whittington, H. B. 1971. Redescription of Marrella splendens (Trilobitoidea) from the Burgess Shale, Middle Cambrian, British Columbia. Geological Survey of Canada, Bulletin 209, 83 p.Google Scholar
Whittington, H. B. 1974. Yohoia Walcott and Plenocaris n. gen. from the Burgess Shale, Middle Cambrian, British Columbia. Geological Survey of Canada, Bulletin 231, 61 p.Google Scholar
Whittington, H. B. 1975. The enigmatic animal Opabinia regalis, Middle Cambrian, Burgess Shale, British Columbia. Philosophical Transactions of the Royal Society of London, B, 271:143.Google Scholar
Whittington, H. B. 1977. The Middle Cambrian trilobite Naraoia, Burgess Shale, British Columbia. Philosophical Transactions of the Royal Society of London, B, 280:409443.Google Scholar
Whittington, H. B. 1978. The lobopod animal Aysheia pedunculata Walcott, Middle Cambrian, Burgess Shale, British Columbia. Pilisophical Transactions of the Royal Society of London, B, 284:165197.Google Scholar
Whittington, H. B. 1980. Exoskeleton, moult stage, appendage morphology, and habits of the Middle Cambrian trilobite Olenoides serratus. Palaeontology, 23:171204.Google Scholar
Whittington, H. B., and Almond, J. E. 1987. Appendages and habits of the Upper Ordovician trilobite Triarthrus eatoni. Philosophical Transactions of the Royal Society of London, B, 317:146.Google Scholar
Yager, J. 1981. Remipedia, a new class of Crustacea from a marine cave in the Bahamas. Journal of Crustacean Biology, 1:328333.Google Scholar
Zhang, W.-T., and Hou, X. G. 1985. Preliminary notes on the occurrence of the unusual trilobite Naraoia in Asia. Acta Paleontologica Sinica, 24:591595.Google Scholar