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The morphology and phylogenetic significance of Kerygmachela kierkegaardi Budd (Buen Formation, Lower Cambrian, N Greenland)

Published online by Cambridge University Press:  03 November 2011

Graham E. Budd
Graham E. Budd
Affiliation:
Department of Earth Sciences, Historical Geology and Palaeontology, University of Uppsala, Norbyvägen 22, Uppsala S-752 36, Sweden [graham.budd@pal.uu.se]
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Abstract

Specimens of Kerygmachela kierkegaardi Budd are described, from the Lower Cambrian Sirius Passet fauna of N Greenland. The cephalic region is characterised by a pair of stout unsegmented appendages each bearing long spinose processes, and an anterior mouth. The trunk shows alternating rows of tubercles and transverse annulations along the axis, to which are attached 11 pairs of gill-bearing lateral lobes and lobopodous limbs. The caudal region is small, and bears two long tail spines. There is some evidence for circular musculature arranged around the trunk and a dorsal, longitudinal sinus, and several details of the muscular pharynx have been preserved.

The combination of characters found in Kerygmachela allows it to be allied with the lobopods, represented in the extant fauna by the onychophorans, tardigrades, and possibly the pentastomids, and in the Cambrian fossil record by a morphologically diverse set of taxa, some of which are not assignable to the extant groupings. It also shares important characters with the previously problematic Burgess Shale forms Opabinia regalis Walcott and AnomalocarisWhiteaves, and the Sirius Passet form Pambdelurion Budd. These taxa together form a paraphyletic group at the base of the clade of biramous arthropods. The position of the so-called ‘Uniramia’ remains unclear. It can be demonstrated from the reconstruction of the arthropod stem-group that full arthropod segmentation has a different derivation from that of the annelids. In line with other recent analyses, this suggests that the ‘Articulata’ of Cuvier should be dismantled, and the arthropods considered to be a group of protostomes which are phylogenetically distinct from the classic spiralians. Arthropod affinities may rather lie with the other moulting animals, in the so-called ‘Ecdysozoa’.

Keywords

AnomalocarisArthropodaexceptional preservationOpabiniaphylogenySirius Passetstem-groups.
Type
Research Article
Information
Earth and Environmental Science Transactions of The Royal Society of Edinburgh , Volume 89 , Issue 4 , 1998 , pp. 249 - 290
Copyright
Copyright © Royal Society of Edinburgh 1998

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References

Abele, L. G., Kim, W. & Felgenhauer, B. E. 1989. Molecular evidence for the inclusion of the phylum Pentastpmida in the Crustacea. Molecular Biology and Evolution 6, 685–91.Google Scholar
Aguinaldo, A. M. A., Turbeville, J. M., Linford, L. S., Rivera, M. C, Garey, J. R., Raff, R. A. & Lake, J. A. 1997. Evidence for a clade of nematodes, arthropods andother moulting animals. Nature 387, 489–93.CrossRefGoogle Scholar
Anderson, D. T. 1966. The comparative early embryology of the Oligochaeta, Hirudinea and Onychophora. Proceedings of the Linnean Society of New South Wales 91, 10–43.Google Scholar
Anderson, D. T. 1973. Embrology and Phylogeny in Annelids and Arthropods. Oxford:Pergamon Press.Google Scholar
Averof, M. & Akam, M. 1993. HOM/Hox genes of Anemia: implications for the origin of insect and crustacean body plans. Current Biology 3, 73–8.CrossRefGoogle Scholar
Averof, M. & Akam, M. 1995. Insect–crustacean relationships: insights from comparative developmental and molecular studies. Philosophical Transactions of the Royal Society of London B 347, 293–03.Google Scholar
Ballard, J. W. O., Olsen, G. J., Faith, D. P., Odgers, W. A., Rowell, D. M. & Atkinson, P. W. 1992. Evidence from 12S rRNA Sequences that Onychophorans are Modified Arthropods. Science 258, 1345–8.CrossRefGoogle Scholar
Barnes, R. D. 1987. Invertebrate Zoology, 5th edn.Philadelphia: W.B. Saunders.Google Scholar
Bergstrom, J. 1976. Early arthropod morphology and relationships. 25th International Geological Congress Abstracts 289. Sydney.Google Scholar
BergstrSm, J. 1986. Opabinia and Anomalocaris, unique Cambrian ‘arthropods. Lethaia 19, 241–6.CrossRefGoogle Scholar
Bergstrom, J. 1987. The Cambrian Opabinia and Anomalocaris. Lethaia 20, 187–8.CrossRefGoogle Scholar
Bergstrom, J. 1989. The origin of animal phyla and the new phylum Procoelomata. Lethaia 22, 259–69.CrossRefGoogle Scholar
Bergstrom, J. 1991. Metazoan evolution around the Precambrian–Cambrian transition. In Simonetta, A. M. & Conway Morris, S.(eds) The early evolution of Metazoa and the significance of problematic taxa, 25–34. Edinburgh: Cambridge University Press.Google Scholar
Blaker, M. R. 1988. A new genus of nevadiid trilobite from the Buen Formation (Early Cambrian) ofPeary Land, central North Greenland. Rapport Gronlands Geologiske Undersogelse 137, 33–41.CrossRefGoogle Scholar
Boudreaux, H. B. 1979. Arthropod phylogeny with special reference to insects. New York: John Wiley.Google Scholar
Briggs, D. E. G. & Fortey, R. A. 1989. The early radiation and relationships of the major arthropod groups. Science 246,241–3.CrossRefGoogle ScholarPubMed
Briggs, D. E. G. 1990. Early arthropods: dampening the Cambrian explosion. Short Coursesin Paleontology 3, 24–43.CrossRefGoogle Scholar
Briggs, D. E. G. & Nedin, C. 1996. The taphonomy and affinities of the problematic fossil Myoscolex from the Lower Cambrian Emu Bay Shale of South Australia. Journal of Paleontology 7, 22–32.Google Scholar
Briggs, D. E. G. & Robison, R. A. 1984. Exceptionally preserved nontrilobite arthropods and Anomalocaris from the Middle Cambrian of Utah. The University of Kansas Paleontological Contributions 111, 1–23.Google Scholar
Briggs, D. E. G. & Whittington, H. B. 1987. The affinities of the Cambrian animals Anomalocaris and Opabinia. Lethaia 20, 185–6.CrossRefGoogle Scholar
Brusca, R. C. & Brusca, G. J. 1990. Invertebrates. Sunderland, Massachussetts: Sinauer.Google Scholar
Budd, G. 1993. A Cambrian gilled lobopod from Greenland. Nature 364, 709–11.CrossRefGoogle Scholar
Budd, G. E. 1995. Kleptothule rasmusseni gen. et sp. nov.: an?olenellinid–like trilobite from theSirius Passet fauna (Buen Formation, GRAHAM Lower Cambrian, North Greenland). Transactions of the Royal Societyof Edinburgh: Earth Sciences 85, 1–12.Google Scholar
Budd, G. E. 1996a. The morphology of Opabinia regalis and the reconstruction of the arthropod stem–group. Lethaia 29, 1–14.CrossRefGoogle Scholar
Budd, G. E. 1996b. Progress and problems in arthropod phylogeny. Tree 11, 356–8.Google ScholarPubMed
Budd, G. E. 1997. Stem–group arthropods from the Lower Cambrian Sirius Passet fauna of North Greenland. In Fortey, R. A. & Thomas, R. H. (eds) Arthropod Relationships, 127–40.London:Chapman & Hall.Google Scholar
Budd, G. E. 1998. Arthropod body–plan evolution in the Cambrian with an example from anomalocaridid muscle. Lethaia 31, 197–210.CrossRefGoogle Scholar
Budd, G. E. & Peel, J. S. 1998. A new xenusiid lobopod from the Early Cambrian SiriusPasset fauna of North Greenland. Palaeontology 41, 1201–13.Google Scholar
Butterfield, N. J. 1990a. Organic preservation of non–mineralising organisms and the taphonomy ofthe Burgess Shale. Paleobiology 16, 287–303.CrossRefGoogle Scholar
Butterfield, N. J. 1990b. A reassessment of the enigmatic Burgess Shale fossil Wiwaxia corrugata (Matthew) and its relationship to the polychaete Canadia spinosa. Paleobiology 16, 287–303.CrossRefGoogle Scholar
Butterfield, N. J. 1995. Secular distribution of Burgess–Shale–type preservation. Lethaia 28, 1–14.CrossRefGoogle Scholar
Chen, J–Y. & Erdtmann, B–D. 1991. Lower Cambrian Lagerstatte from Chengjiang, Yunnan, China: insights for reconstructing early metazoan life. In Simonetta, A. M. & Conway Morris, S.(eds) The early evolution of Metazoa and the significance of problematic taxa, 57–76. Edinburgh: Cambridge University Press.Google Scholar
Chen, J–Y., Hou, X–G. & Lu, H. Zh. 1989. Early Cambrian netted scale–bearing worm–like sea animal. Ada Palaeontologica Sinicai 28, 1–16.Google Scholar
Chen, J–Y., Ramskold, L. & Zhou, G. q. 1994. Evidence for monophyly and arthropod affinity of Cambrian giant predators. Science 264, 1304–8.CrossRefGoogle ScholarPubMed
Chen, J–Y., Zhou, G–Q. & Ramskold, L. 1995a. A new Early Cambrian onychophoran–like animal, Paucipodia gen nov., from the Chengjiang fauna, China. Transactions of the Royal Society ofEdinburgh: Earth Sciences 85, 275–82.Google Scholar
Chen, J–Y., Zhou, G–Q. & Ramskold, L. 1995. The Cambrian lobopodian Microdictyon sinicum. Bulletin of the National Museum of Natural Science (Taichung, Taiwan) 5, 1–93.Google Scholar
Chen, J–Y., Edgecombe, G. D., Ramskold, L & Zhou, G.–Q. 1995c. Head segmentation in Early Cambrian Fuxianhuia: implications for arthropod evolution. Science 268, 1339–43.CrossRefGoogle ScholarPubMed
Chen, J–Y., Edgecombe, G. D. & Ramskold, L. 1997. Morphological and ecological disparity in naraoiids (Arthropoda) from the Early Cambrian Chengjiang Fauna, China. Records of the Australian Museum 49, 1–24.CrossRefGoogle Scholar
Collins, D. H. 1992. Whither Anomalocaris? The search in the BurgessShale continues. Special Publication of the Paleontological Society(Fifth North American Paleontology Convention Abstracts) 6, 66.CrossRefGoogle Scholar
Collins, D. H. 1996. The ‘evolution’ of Anomalocaris and its classification in the arthropod class Dinocarida (Nov.) andOrder Radiodonta (Nov.). Journal of Paleontology 70, 280–93.CrossRefGoogle Scholar
Collins, D., Briggs, D. E. G. & Conway Morris, S. 1983. New Burgess Shale fossil sites reveal Middle Cambrian faunal complex. Science 222, 163–7.CrossRefGoogle ScholarPubMed
Conway Morris, S. 1977. A new Metazoan from the Burgess Shale of British Columbia. Palaeontology 20, 623–40.Google Scholar
Conway Morris, S. 1986. The community structure of the Middle Cambrian Phyllopod Bed (Burgess Shale). Palaeontology 29, 423–68.Google Scholar
Conway Morris, S. 1989. The persistence of Burgess Shale–type faunas: implications for the evolution of deeper–water faunas. Transactions of the Royal Society of Edinburgh: Earth Sciences 80, 271–83.CrossRefGoogle Scholar
Conway Morris, S. 1991. Problematic taxa: a problem for biology or biologists? In Simonetta, A. M. & Conway Morris, S. (eds) The early evolution of Metazoa and the significance of problematic taxa, 19–24. Edinburgh: Cambridge University Press.Google Scholar
Conway Morris, S. 1993. The fossil record and the early evolution of the metazoa. Nature 361, 219–25.CrossRefGoogle Scholar
Conway Morris, S. 1994. Why molecular biology needs palaeontology. Development supplement, 1–13.Google Scholar
Conway Morris, S. 1997. The cuticular structure of the 495–Myr–old type species of the fossil worm Palaeoscolex P. piscatorum (?Priapulida). Zoological Journal of the Linnean Society 119, 69–82.CrossRefGoogle Scholar
Conway Morris, S. 1998. The crucible of creation. Oxford: Oxford UniversityPress.Google Scholar
Conway Morris, S. & Peel, S. J. 1990. Articulated halkieriids from the Lower Cambrianof North Greenland. Nature 345, 802–4.CrossRefGoogle Scholar
Conway Morris, S. & Peel, S. J. 1995. Articulated halkieriids from the Lower Cambrianof North Greenland and their role in early protostome evolution. Philosophical Transactions of the Royal Society of London B 347, 305–58.Google Scholar
Conway Morris, S., Peel, J. S., Higgins, A. K., Soper, N. J. & Davis, N. C. 1987. A Burgess Shale–like fauna from the Lower Cambrian of North Greenland. Nature 345, 802–5.CrossRefGoogle Scholar
Conway Morris, S. & Robison, R. A. 1988. More soft–bodied animals and algae from the Middle Cambrian of Utah and British Columbia. The University of Kansas Paleontological Contributions 122.Google Scholar
Cuvier, G. 1817. Lè regne animal distribué d'aprés son organisation, pour servir de base à I'histoire naturelle des animaux et d'introduction a I'anatomie comparee.Vol. 2. Paris: Deterville, [in French].Google Scholar
Davis, N. C. & Higgins, A. K. 1987. Cambrian–Lower Silurian stratigraphy in the fold and thrust zone between northern Nyeboe Land and J.P. Koch Fjord, North Greenland. Rapport Grenlands Geologiske Undersogelse 133, 91–8.CrossRefGoogle Scholar
De Robertis, E. M., Oliver, G. & Wright, C. V. E. 1989. Determination of axispolarity in the vertebrate embryo: homeodomain proteins and homeogenetic induction. Cell 57, 189–91.CrossRefGoogle ScholarPubMed
Dewel, R. A. & Dewel, W. C. 1996. The brain of Echiniscus viridissimus Peterfi 1956 (Heterotardigrada): a key to understanding the phylogenetic position of tardigrades and the evolution of the arthropod head. Zoological Journal of the Linnean Society of London 116, 35–49.CrossRefGoogle Scholar
Dewel, R. A. & Dewel, W. C. 1997. The place of tardigrades in arthropod evolution. In Fortey, R. A. & Thomas, R. H. (eds)Arthropod Relationships, 109–23. London: Chapman & Hall.Google Scholar
Dewel, R. A., Budd, G. E., Castano, D. F. & Dewel, W. C. (in press). The organization of the subesophageal nervous system in tardigrades: insights into the evolution of the arthropod labrum and tritocerebrum. Acta Biologica Benrodis.Google Scholar
Dzik, J. 1991. Is fossil evidence consistent with traditional views of metazoan phylogeny? In Simonetta, A. M. & Conway Morris, S. (eds) The early evolution of Metazoa and the significanceof problematic taxa, 47–56. Edinburgh: Cambridge University Press.Google Scholar
Dzik, J. & Krumbeigel, G. 1989. The oldest ‘onychophoran’ Xenusion: a link connecting phyla? Lethaia 22, 169–81.CrossRefGoogle Scholar
Dzik, J. & Lendzion, K. 1988. The oldest arthropods of the East European Platform. Lethaia 21, 29–38.CrossRefGoogle Scholar
Eernisse, D. J., Albe, J. S. & Anderson, F. E. 1992. Annelida and Arthropoda are not sister taxa: a phylogenetic analysis of spiralian metazoan morphology. Systematic Biology 41, 305–30.CrossRefGoogle Scholar
Emerson, M. J. & Schram, F. R. 1990a. The origin of Crustacean biramous appendages and the evolution of the Arthropoda. Science 250, 667–9.CrossRefGoogle ScholarPubMed
Emerson, M. J. & Schram, F. R. 1990b. A novel hypothesis for the origin of biramous appendages in crustaceans. Short Courses in Paleontology 3, 157–76. Paleontological Society.CrossRefGoogle Scholar
Fortery, R. A. & Thomas, R. H. 1997. Arthropod relationships. London:Chapman & Hall.Google Scholar
Friedrich, M. & Tautz, D. 1995. Ribosomal DNA phylogeny of the major extant arthropodclasses and the evolution of myriapods. Nature 376, 165–7.CrossRefGoogle ScholarPubMed
Fryer, G. 1996. Reflections on arthropod evolution. Biological Journal of the Linnean Society of London 58, 1–55.CrossRefGoogle Scholar
Giribet, G., Carranza, S., Baguna, J., Riuto, M. & Ribera, C. 1996. First molecular evidence for the existence of a Tardigrada plus Arthropoda clade. Molecular Biology and Evolution 13, 76–84.CrossRefGoogle Scholar
Glaessner, M. F. 1979. Lower Cambrian Crustacea and annelid–like worms from Kangaroo Island, South Australia. Alcheringa 3, 21–31.CrossRefGoogle Scholar
Gould, S. J. 1989. Wonderful Life. The Burgess shale and the nature of history. New York: W.W. Norton.Google Scholar
Greven, H. 1984. Tardigrada. In Bereiter–Hahn, J., Matlotsky, A. G. & Richards, K. S. (eds) Biology of the Integument 1,715–27. Berlin: Springer.Google Scholar
Grotzinger, J. P., Bowring, S. A., Saylor, B. Z. & Kaufman, A. J. 1995. Biostratigrhic and geochronologic constraints on early animal evolution. Science 270, 598–604.CrossRefGoogle Scholar
Guilding, L. 1826. Molusca Carribeana. 2. An account of a new genus of Mollusca. Zoological Journal 2, 437–44.Google Scholar
Higgins, A., Ineson, J. R., Peel, J. S., Surlyk, F. & Sanderholm, M. 1991. Lower Palaeozoic Franklinian Basin of North Greenland. Bulletin Gronlands Geologiske Undersogelse 160, 71–139.CrossRefGoogle Scholar
Hintz, I., Kraft, P., Mergl, M & Müller, K. J. 1990. The problematic Hadimopanella, Kaimenella, Milaculum and Utahphospha identified as sclerites of Palaeoscolecida. Lethaia 23, 217–21.CrossRefGoogle Scholar
Holland, L. Z., Kene, M., Williams, N. A. & Holland, N. D. 1997. Sequence and embryonic expression of the amphioxus engrailedgene (AmphiEn): the metameric pattern of transcription resemblesthat of its segment–polarity homolog in Drosophila. Development 124, 1723–32.CrossRefGoogle Scholar
Hou, X–G. & Bergström, J. 1991. The arthropods of the Lower Cambrian Chengjiang fauna, with relationships and evolutionary significance. In Simonetta, A. M. & Conway Morris, S. (eds) The early evolution ofMetazoa and the significance of problematic taxa, 179–87. Edinburgh: Cambridge University Press.Google Scholar
Hou, X–G. & Bergström, J. 1994. Palaeoscolecid worms may be nematomorphs rather than annelids. Lethaia 27, 11–17.Google Scholar
Hou, X–G. & Bergström, J. 1995. Cambrian lobopodians–ancestors of extant onychophorans? Zoological Journal of the Linnean Society of London 114, 3–19.CrossRefGoogle Scholar
Hou, X–G. & Bergström, J. 1997. Arthropods of the Lower Cambrian Chengjiang fauna, southwest China. Fossils and Strata 45, 1–116.Google Scholar
Hou, X–G., Bergström, J. & Ahlberg, P. 1995. Anomalocaris and other large animals in the Lower Cambrian Chengjiang faunaof southwest China. GFF 117, 163–83.Google Scholar
Hou, X–G. &. Chen, J. Y. 1989. Early Cambrian arthropod–annelid intermediate sea animal, Luolishania gen. nov. from Chengjiang, Yunnan. Ada Palaeontologica Sinica 28, 207–13.Google Scholar
Hou, X–G., Ramsköld, L. & Bergstrom, J. 1991. Composition and preservation ofthe Chengjiang fauna–a Lower Cambrian softbodied biota. Zoologica Scripta (Stockholm) 20, 395–411.Google Scholar
Hutchinson, G. E. 1930. Restudy of some Burgess Shale fossils. Proceedings of the U.S. National Museum 78, 1–24.CrossRefGoogle Scholar
Ineson, J. R. & Peel, J. S. 1997. Cambrian shelf stratigraphy of North Greenland. Geology of Greenland Survey Bulletin 173, 1–120.CrossRefGoogle Scholar
Kielan, Z. 1960. On two olenellid trilobites from Vestspitsbergen. Studia Geologica Polonica 4, 83–92.Google Scholar
Kimmel, C. B. 1996. Was Urbilateria segmented? Trends in Genetics 12, 329–31.CrossRefGoogle ScholarPubMed
Kinchin, I. M. 1994. The Biology of Tardigrades. London: Portland Press.Google Scholar
Kraus, O. & Kraus, M. 1996. On myriapod/insect interrelationships. Memoires du Museum National D'Histoire Naturelle (Serie A: Zoologie) 169, 283–90.Google Scholar
Lake, J. A. 1990. Origin of the Metazoa. Proceedings of the National Academy of Sciencesof the USA 87, 763–6.CrossRefGoogle ScholarPubMed
Lans, D., Wedeen, C. J. & Weisblat, D. A. 1993. Cell lineage analysis of the expression of an engrailed homolog in leechembryos. Development 117, 857–71.CrossRefGoogle Scholar
Manton, S. M. 1960. Concerning head development in the arthropods. Biological Reviews 35, 265–82.CrossRefGoogle Scholar
Manton, S. M. 1977. The Arthropoda: Habits, Functional Morphology and Evolution. Oxford: Oxford University Press.Google Scholar
Mosely, H. N. 1874. Peripatus capensis Grube. Observations on its structure and development.Proceedings of the Royal Society of London 22, 344–50.Google Scholar
Nedin, C. 1995. The Emu Bay Shale, a Lower Cambrian fossil Largerstdtten, Kangeroo Island, South Australia. Memoirs of the Association of Australasian Palaeontologists 18, 31–40.Google Scholar
Nielsen, C. 1995. Animal evolution. Oxford: Oxford University Press.Google Scholar
Neuhaus, B. 1994. Ultrastructure of alimentary canal and body cavity, ground pattern, and phylogenetic relationships of the Kinorhynchia. Microfauna Marina 9, 61–156.Google Scholar
Neuhaus, B. 1995. Postembryonic development of Paracentrophyes praedictus (Homalorhagida): neotony questionable among the Kinorhyncha. Zoologica Scripta 24, 179–92.CrossRefGoogle Scholar
Palmer, A. R. & Repina, L. N. 1993. Through a glass darkly: taxonomy, phylogeny, and biostratigraphy of the Olenellina. The University of Kansas Paleontological Contributions (New Series) 3, 1–35.Google Scholar
Peel, J. S. & Senderholm, M. (eds) 1991. Sedimentary basins of North Greenland. Bulletin Gronlands Geologiske Undersogelse 160, 1–164.Google Scholar
Peel, J. S. & Vidal, G. 1993. Acritarchs from the Lower Cambrian Buen Formation in north Greenland. Bulletin Gronlands Geologiske Undersogelse 164, 1–35.Google Scholar
Poinar, G. 1996. Fossil velvet worms in Baltic and Dominican amber: Onychophoran evolution and biogeography Science 273, 1370–1.CrossRefGoogle Scholar
Poulsen, V. 1974. Olenellacean trilobites from eastern North Greenland. Bulletin of the Geological Society of Denmark 23, 79–101.Google Scholar
Raff, R. A., Field, K. G., Olsen, G. J., Giovannoni, S. J., Lane, D. J., Ghiselin, M. T., Pace, N. R. & Raff, E. C. 1989. Metazoan phylogeny based on analysis of 18S ribosomal RNA. In Fernholm, B., Bremer, K. & Jornvall, H. (eds) The Hierarchy of Life, 247–60. Amsterdam: Elsevier.Google Scholar
Raineri, M. 1985. Histological investigations of Tardigrada 2. Alkaline phosphatase (ALP) and aminopeptidase (AMP) in the alimentary apparatus of Eutardigrada. Monitore Zoologico Italiano (NS) 19,47–67.Google Scholar
Ramsköld, L. 1992a. The second leg row of Hallucigenia discovered. Lethaia 25, 221–4.CrossRefGoogle Scholar
Ramsköld, L. 1992b. Homologies in Cambrian Onychophora. Lethaia 25, 443–60.CrossRefGoogle Scholar
Ramsköld, L. 1995. From characters to clades: interpreting lobopodians and anomalocaridids. In Chen, J. Y., Edgecombe, G. & Ramskold, L. (eds), International Cambrian Explosion Symposium (Nanjing), Abstracts 22.Google Scholar
Ramsköld, L. & Chen, J–Y. 1998. Cambrian lobopodians: morphology and phylogeny. In Edgecombe, G. (ed.) Athropod fossils and phylogeny, 77–93. New York: Columbia University Press.Google Scholar
Ramsköld, L. & Hou, X. G. 1991. New Early Cambrian animal and onychophoran affinitiesof enigmatic metazoans. Nature 351, 225–8.CrossRefGoogle Scholar
Rempel, J. G. 1975. The evolution of the insect head: the endless dispute. Quaestiones Entomologicae 11, 7–25.Google Scholar
Rigby, J. K. 1986. Cambrian and Silurian sponges from North Greenland. Rapport GronlandsGeologiske Undersogelse 132, 51–63.CrossRefGoogle Scholar
Robison, R. A. 1985. Affinities of Aysheaia (Onychophora) with descriptions of a new Cambrian species. Journal of Paleontology 59, 226–35.Google Scholar
Robison, R. A. 1990. Earliest known uniramous arthropod. Nature 343, 163–4.CrossRefGoogle Scholar
Robison, R. A. 1991. Middle Cambrian biotic diversity: examples from four Utah Lagerstatten.In Simonetta, A. M. & Conway Morris, S. (eds), The early evolution of Metazoa and the significance of problematic taxa, 77–93. Edinburgh: CambridgeUniversity Press.Google Scholar
Robison, R. A. & Wiley, E. O. 1995. A new arthropod, Meristosoma; more fallout from the Cambrian explosion. Journal of Paleontology 69, 447–59.CrossRefGoogle Scholar
Runnegar, B. & Fedonkin, M. A. 1992. Proterozoic metazoan body fossils. In Schopf, W. J. & Klein, C. (eds) The Proterozoic biosphere; a multidisciplinary study, 369–88. Edinburgh: Cambridge University Press.Google Scholar
Schmidt–Rhaesa, A., Bartolomaeus, T., Lemburg, C, Ehlers, U. & Garey, J. R. 1998. The position of the Arthropoda in the phylogenetic system. Journal of Morphology 238, 263–85.3.0.CO;2-L>CrossRefGoogle ScholarPubMed
Shear, W. A. 1992. End of the ‘Uniramia’ taxon. Nature 359, 477–8.CrossRefGoogle Scholar
Shu, D.–G., Geyer, G., Chen, L. & Zhang, X.I. 1995. Redlichiacean trilobites with preserved soft–parts from the Lower Cambrian Chengjiang fauna (South China). Beringeria Special Issue 2, 203–41.Google Scholar
Simonetta, A. M. 1970. Studies on the non–Trilobite Arthropods of the Burgess Shale (Middle Cambrian). Palaeontologica Italica 66 (N.S. 39), 35–45.Google Scholar
Slack, J. M. W., Holland, P. W. H. & Graham, C. F. 1993. The zootype and the phylotypic stage. Nature 361, 490–2.CrossRefGoogle ScholarPubMed
Snodgrass, R. E. 1938. Evolution of the Annelida, Onychophora and Arthropoda. Smithsonian Miscellaneous Collections 97, 1–159.Google Scholar
Störch, V. 1984. Onychophora. In Bereiter–Hahn, J., Matlotsky, A. G. & Richards, K. S. (eds) Biology of the Integument 1, 703–8. Berlin: Springer–Verlag.CrossRefGoogle Scholar
Störch, V., Higgins, R. P. & Morse, M. P. 1989. Ultrastructure of the body wall of Meiopriapulus fijiensis (Priapulida). Transactions of the American Microscopical Society 108, 319–31.CrossRefGoogle Scholar
Tait, N. N., Briscoe, D. A. & Rowell, D. M. 1995. Onychophora–ancient and modern radiations. Memoirs of the Association of Australasian Palaeontologists 18, 21–30.Google Scholar
Thompson, I. & Jones, D. S. 1980. A possible onychophoran from the Middle Pennsylvanian Mazon Creek Beds of northern Illinois. Journal of Paleontology 54, 588–96.Google Scholar
Tiegs, O. W. & Manton, S. M. 1958. The evolution of the Arthropoda. Biological Reviews 33, 255–337.CrossRefGoogle Scholar
Turbeville, J. M., Pfeifer, D. M., Field, K. G. & Raff, R. A. 1991. The phylogenetic status of arthropods, as inferred from 18S rRNA sequences. Molecular Biology and Evolution 8, 669–86.Google ScholarPubMed
Valentine, J. W. 1994. Late Precambrian bilaterians: Grades and clades. Proceedings of the National Academy of Science, USA 91, 6751–7.CrossRefGoogle ScholarPubMed
Valentine, J. W., Erwin, D. H. & D. Jablonski, D. 1996. Developmental evolution of metazoan bodyplans: The fossil evidence. Developmental Biology 173, 373–81.CrossRefGoogle ScholarPubMed
Vidal, G., Moczydlowska, M. & Rudavskaya, V. R. 1995. Constraints on the early Cambrian radiation and correlation of the Tommotian and Nemakit–Daldynian regional stages of eastern Siberia. Journal of the Geological Society, London 152, 499–510.CrossRefGoogle Scholar
Vogel, S. 1988. Life's Devices. New Hampshire: Princeton Press.Google Scholar
Wagele, J. W. 1993. Rejection of the ‘Uniramia’ hypothesis and 290 implications of the Mandibulata concept. Zoologische Jahrbücher. Abtheilung fur Systematik, Geographie und Biologie der Thiere 120, 253–88.Google Scholar
Wagele, J. W. & Stanjek, G. 1995. Arthropod phylogeny inferred from partial 12S rRNA revisited–monophyly of the Tracheata depends on sequence alignment. Journal of Zoological Systematics andEvolutionary Research 33, 75–80.CrossRefGoogle Scholar
Wagele, J. W. & Wetzel, R. 1994. Nucleic acid sequences are not per se reliable for the inference of phylogenies. Journal of Natural History 28, 749–61.CrossRefGoogle Scholar
Waggoner, B. M. 1996. Phylogenetic hypotheses of the relationships of arthropods to Precambrian and Cambrian problemation fossil taxa. Systematic Biology 45, 190–222.CrossRefGoogle Scholar
Walcott, C. D. 1911a. Middle Cambrian Merostomata. Cambrian Geology and Paleontology, II. Smithsonian Miscellaneous Collections 57, 17–40.Google Scholar
Walcott, C. D. 1911b. Middle Cambrian holothurians and medusae. Cambrian Geology and Paleontology, II. Smithsonian Miscellaneous Collections 57, 41–68.Google Scholar
Walcott, C. D. 1911c. Middle Cambrian annelids. Cambrian Geology and Paleontology, II. Smithsonian Miscellaneous Collections 57, 109–44.Google Scholar
Walcott, C. D. 1912. Middle Cambrian Branchiopoda, Malacostraca, Trilobita and Merostomata. Cambrian Geology and Paleontology, II. Smithsonian Miscellaneous Collections 57, 145–228.Google Scholar
Walossek, D. 1993. The Upper Cambrian Rehbachiella and the phylogeny of Branchiopoda and Crustacea. Fossils and Strata 32, 1–202.CrossRefGoogle Scholar
Walossek, D. & Müller, K. J. 1990. Upper Cambrian stem–lineage crustaceans and their bearing upon the monophyletic origin of Crustacea and the position of Agnostus. Lethaia 23, 409–27.CrossRefGoogle Scholar
Walossek, D. & Müller, K. J. 1994. Pentastomid parasites from the Lower Palaeozoic of Sweden. Transactions of the Royal Society of Edinburgh: Earth Sciences 85, 1–37.CrossRefGoogle Scholar
Walossek, D. & Müller, K. J. 1997. Cambrian ‘orsten’–type arthropodsand the phylogeny of Crustacea. In Fortey, R.A. & Thomas, R.H. (eds) Arthropod Relationships, 139–53. London: Chapman & Hall.Google Scholar
Walossek, D. & Müller, K. J. 1998. Early arthropod phylogeny in light of the Cambrian ‘orsten’ fauna. In Edgecombe, G.D.(ed.)Arthropod fossils and phylogeny, 185–231. New York: Columbia University Press.Google Scholar
Wedeen, C. J., Kostriken, R. G., Leach, D. & Whitington, P. 1997. Segmentally iterated expression of an engrailed–class gene in the embryo of an australian onychophoran. Development, Genes and Evolution 207, 282–6.CrossRefGoogle ScholarPubMed
Wheeler, W.C., Cartwright, P & Hayashi, C. Y. 1993. Arthropod phylogeny; a combined approach. Cladistics 9, 1–39.CrossRefGoogle ScholarPubMed
Whittington, H. B. 1974. Yohoia Walcott and Plenocaris n. gen., arthropods from the Burgess Shale, Middle Cambrian, British Columbia. Geological Survey of Canada Bulletin 231, 1–21.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, 1–43.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, 409–43.Google Scholar
Whittington, H. B. 1978. The lobopodian animal Aysheaia pedunculata Walcott, Middle Cambrian, Burgess Shale, British Columbia. Philosophical Transactions of the Royal Society of London B 284, 165–97.Google Scholar
Whittington, H. B. 1985a. The Burgess Shale. New Haven: Yale University Press.Google Scholar
Whittington, H. B. 1985b. Tegopelte gigas, a second soft–bodied trilobite from the Burgess Shale, Middle Cambrian, British Columbia. Journal of Paleontology 59, 1251–74.Google Scholar
Whittington, H. B. 1993. Anatomy of the Ordovician trilobite Placoparia. Philosophical Transactions of the Royal Societyof London B 339, 109–18.Google Scholar
Whittington, H. B. & 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
Williams, M., Siveter, D. J. & Peel, J. S. 1996. Isoxys (Arthropoda)from the Early Cambrian Sirius Passet Lagerstatte, North Greenland. Journal of Paleontology 70, 947–54.CrossRefGoogle Scholar
Willmer, P. 1990. Invertebrate relationships. Edinburgh: Cambridge University Press.CrossRefGoogle Scholar
Wills, M. A., Briggs, D. E. G., Fortey, R. A. & Wilkinson, M. 1995. The significance of fossils in understanding arthropod evolution. Verhandlungen der Deutschen Zoologischen Gesellschaft 88, 203–15.Google Scholar
Wingstrand, K. G. 1985. On the anatomy and relationships of recent Monoplacophora. Galathea Report 16, 7–94 + 12 pis.Google Scholar
Winnepenninckx, B., Backeljau, T. & De Wachter, R. 1995. Phylogeny of protostome worms derived derived from 18S rRNA sequences. Molecular Biology and Evolution 12, 641–9.Google ScholarPubMed
Zang, W. L. 1992. Sinian and Early Cambrian floras and biostratigraphy of the South China Platform. Palaeontographica 224, 75–119.Google Scholar