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A new arthropod, Meristosoma: More fallout from the Cambrian explosion

Published online by Cambridge University Press:  20 May 2016

R. A. Robison  and
E. O. Wiley
R. A. Robison
Affiliation:
Department of Geology and Department of Systematics and Ecology, University of Kansas, Lawrence 66045
E. O. Wiley
Affiliation:
Department of Geology and Department of Systematics and Ecology, University of Kansas, Lawrence 66045
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Abstract

New Middle Cambrian fossils demonstrate unusual tagmosis within the Arthropoda. Rare specimens from the Spence Shale of northern Utah are assigned to Meristosoma paradoxum n. gen. and sp. One specimen from the Marjum Formation of west-central Utah is assigned to Meristosoma sp. These taxa are further assigned to the new family Meristosomatidae. Meristosoma, which reached 17 cm in length, is characterized by a short anterior shield, a long thorax with 36 or more articulating segments, and a posterior shield with as many as 11 fused segments. Its short anterior shield and long, multisegmented thorax have a myriapodan aspect, but Meristosoma differs from all myriapods by its posterior tagmosis. In dorsal view, its posterior shield is most like that of some macropygous trilobites, but Meristosoma differs from all trilobites by having a shorter anterior shield, ringed thoracic segments without trilobation, and no ventral doublure. Phylogenetic analysis indicates that Meristosoma is a primitive and basal arthropod. A more precise taxonomic assignment is hampered by a lack of information about its limb morphology.

Type
Research Article
Information
Journal of Paleontology , Volume 69 , Issue 3 , May 1995 , pp. 447 - 459
Copyright
Copyright © The Paleontological Society 

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References

Archie, J. W. 1989a. A randomization test for phylogenetic information in systematic data. Systematic Zoology, 38:239–252.CrossRefGoogle Scholar
Archie, J. W. 1989b. Homoplasy excess ratios: new indices for measuring levels of homoplasy in phylogenetic systematics and a critique of the consistency index. Systematic Zoology, 38:253–269.CrossRefGoogle Scholar
Briggs, D. E. G. 1983. Affinities and early evolution of the Crustacea: the evidence of the Cambrian fossils, p. 1–22. In Schram, F. R. (ed.), Crustacean Phylogeny. A. A. Balkema, Rotterdam.Google Scholar
Briggs, D. E. G., and Fortey, R. A. 1992. The early Cambrian radiation of arthropods, p. 335–373. In Lipps, J. H. and Signor, P. W. (eds.), Origin and Early Evolution of the Metazoa. Plenum Press, New York.CrossRefGoogle Scholar
Briggs, D. E. G., and Wills, M. A. 1992. Morphological disparity in the Cambrian. Science, 256:1670–1673.CrossRefGoogle ScholarPubMed
Briggs, D. E. G., and Wills, M. A. 1993. How big was the Cambrian evolutionary explosion? A taxonomic and morphological comparison of Cambrian and Recent arthropods, p. 33–44. In Edwards, D. and Lees, D. (eds.), Evolutionary Patterns and Processes. Academic Press, London.Google Scholar
Conway Morris, S. 1993. The fossil record and the early evolution of the Metazoa. Nature, 361:219–225.CrossRefGoogle Scholar
Erwin, D. H. 1991. Metazoan phylogeny and the Cambrian radiation. Trends in Ecology and Evolution, 6:131–134.CrossRefGoogle ScholarPubMed
Farris, J. S. 1989. The retention index and the rescaled consistency index. Cladistics, 5:417–419.CrossRefGoogle ScholarPubMed
Felsenstein, J. 1986. Confidence limits on phylogenies: an approach using the bootstrap. Evolution, 39:783–791.CrossRefGoogle Scholar
Foote, M., Gould, S. J., and Lee, S. Y. 1992. Cambrian and recent morphological disparity [with response by D. E. G. Briggs, R. A. Fortey, and M. A. Wills]. Science, 258:1816–1818.CrossRefGoogle ScholarPubMed
Gould, S. J. 1989. Wonderful Life: The Burgess Shale and the Nature of History. W. W. Norton & Company, New York, 347 p.Google Scholar
Gunther, L. F., and Gunther, V. G. 1981. Some Middle Cambrian fossils of Utah. Brigham Young University Geology Studies, 28(1):1–81.Google Scholar
Hillis, D. L. 1991. Discriminating between phylogenetic signal and random noise in DNA sequences, p. 278–294. In Miyamoto, M. M. and Cracraft, J. (eds.), Phylogenetic Analysis of DNA Sequences. Oxford University Press, New York.CrossRefGoogle Scholar
Hillis, D. L., and Bull, J. J. 1993. An empirical test of bootstrapping as a method for assessing confidence in phylogenetic analysis. Systematic Zoology, 42:182–192.Google Scholar
Hillis, D. L., and Huelsenbeck, J. 1992. Signal, noise, and reliability in molecular phylogenetic analysis. Journal of Heredity, 23:189–195.CrossRefGoogle Scholar
Xian-Guang, Hou. 1987. Three new large arthropods from Lower Cambrian, Chenjiang, eastern Yunnan. Acta Palaeontologica Sinica, 26:272–285.Google Scholar
Levinton, J. S. 1992. The big bang of animal evolution. Scientific American, 267(5):84–91.CrossRefGoogle ScholarPubMed
Maddison, W. P., and Maddison, D. R. 1992. MacClade, version 3.0. Sinauer Associates, Sunderland, Massachusetts.Google Scholar
Manton, S. M. 1977. The Arthropoda: Habits, Functional Morphology, and Evolution. Clarendon Press, Oxford, 527 p.Google Scholar
Palmer, A. R. 1958. Morphology and ontogeny of a Lower Cambrian ptychoparioid trilobite from Nevada. Journal of Paleontology, 32:154–170.Google Scholar
Plotnick, R. E. 1985. Lift based mechanisms for swimming in eurypterids and portunid crabs. Transactions of the Royal Society of Edinburgh, Earth Sciences, 76:325–337.CrossRefGoogle Scholar
Robison, R. A. 1967. Ontogeny of Bathyuriscus fimbriatus and its bearing on affinities of corynexochid trilobites. Journal of Paleontology, 41:213–221.Google Scholar
Robison, R. A. 1976. Middle Cambrian trilobite biostratigraphy of the Great Basin. Brigham Young University Geology Studies, 23(2):93–109.Google Scholar
Robison, R. A. 1984. Cambrian Agnostida of North America and Greenland; Part I, Ptychagnostidae. University of Kansas Paleontological Contributions, Paper 109, 59 p.Google Scholar
Robison, R. A. 1991a. Cambrian Period. Encyclopaedia Britannica, 19:785–792.Google Scholar
Robison, R. A. 1991b. Middle Cambrian biotic diversity: examples from four Utah lagerstätten, p. 77–98. In Simonetta, A. and Conway Morris, S. (eds.), The Early Evolution of Metazoa and the Significance of Problematic Taxa. Cambridge University Press, Cambridge.Google Scholar
Runnegar, B. 1992. Evolution of the earliest animals, p. 65–93. In Schopf, J. W. (ed.), Major Events in the History of Life. Jones and Bartlett Publishers, Boston.Google Scholar
Swofford, D. L. 1990. PAUP: phylogenetic analysis using parsimony, version 3.0. Illinois Natural History Survey, Champaign, Illinois.Google Scholar
Valentine, J. W., Awramik, S. M., Signor, P. W., and Sadler, P. M. 1991. The biological explosion at the Precambrian–Cambrian boundary. Evolutionary Biology, 25:279–356.Google Scholar
Walcott, C. D. 1908. Cambrian geology and paleontology; No. 2, Cambrian trilobites. Smithsonian Miscellaneous Collections, 53:13–52.Google Scholar
Walcott, C. D. 1912. Cambrian geology and paleontology II: Middle Cambrian Branchiopoda, Malacostraca, Trilobita, and Merostomata. Smithsonian Miscellaneous Collections, 57:145–228.Google Scholar
Walcott, C. D. 1931. Addenda to descriptions of Burgess Shale fossils. Smithsonian Miscellaneous Collections, 85(3):1–46.Google Scholar
Whittington, H. B. 1957. The ontogeny of trilobites. Biological Reviews, 32:421–469.CrossRefGoogle Scholar
Whittington, H. B. 1971a. The Burgess Shale: history of research and preservation of fossils, p. 1170–1201. In Yochelson, E. L. (ed.), Proceedings of the North American Paleontological Convention, Volume 2. Allen Press, Lawrence, Kansas.Google Scholar
Whittington, H. B. 1971b. Redescription of Marrella splendens (Trilobitoidea) from the Burgess Shale, Middle Cambrian, British Columbia. Geological Survey of Canada, Bulletin 209, 24 p.CrossRefGoogle Scholar
Whittington, H. B. 1977. The Middle Cambrian trilobite Naraoia, Burgess Shale, British Columbia. Philosophical Transactions of the Royal Society of London (B), 280:409–443.Google Scholar
Whittington, H. B., and Briggs, D. E. G. 1985. The largest Cambrian animal, Anomalocaris, Burgess Shale, British Columbia. Philosophical Transactions of the Royal Society of London (B), 309:569–609.Google Scholar