Hostname: page-component-7c8c6479df-8mjnm Total loading time: 0 Render date: 2024-03-28T13:05:43.371Z Has data issue: false hasContentIssue false

Phylogenetic analysis of some basal early Cambrian trilobites, the biogeographic origins of the Eutrilobita, and the timing of the Cambrian radiation

Published online by Cambridge University Press:  14 July 2015

Bruce S. Lieberman*
Affiliation:
Departments of Geology and Ecology and Evolutionary Biology, University of Kansas, 120 Lindley Hall, Lawrence, 66045-7613,

Abstract

This paper presents a phylogenetic analysis of the “Fallotaspidoidea,” a determination of the biogeographic origins of the eutrilobites, and an evaluation of the timing of the Cambrian radiation based on biogeographic evidence. Phylogenetic analysis incorporated 29 exoskeletal characters and 16 ingroup taxa. In the single most parsimonious tree the genus Fallotaspidella Repina, 1961, is the sister taxon of the sutured members of the Redlichiina Richter, 1932. Phylogenetic analysis is also used to determine the evolutionary relationships of two new species of “fallotaspidoids” distributed in the White-Inyo Range of California that have been previously illustrated but not described. These species had been referred to Fallotaspis Hupé, 1953, and used to define the occurrence of the eponymous Fallotaspis Zone in southwestern Laurentia. However, these two new species need to be reassigned to Archaeaspis Repina in Khomentovskii and Repina, 1965. They are described as Archaeaspis nelsoni and A. macropleuron. Their phylogenetic status suggests that the Fallotaspis Zone in southwestern Laurentia is not exactly analogous to the Fallotaspis Zone in Morocco, where that division was originally defined. Thus, changes to the biostratigraphy of the Early Cambrian of southwestern Laurentia may be in order. Furthermore, specimens of a new species referable to Nevadia Walcott, 1910, are recognized in strata traditionally treated as within the Fallotaspis Zone, which is held to underlie the Nevadella Zone, suggesting further biostratigraphic complexity within the basal Lower Cambrian of southwestern Laurentia.

Phylogenetic analyses of the Olenellina and Olenelloidea, along with the phylogenetic analysis presented here, are used to consider the biogeographic origins of the eutrilobites. The group appears to have originated in Siberia. Biogeographic patterns in trilobites, especially those relating to the split between the Olenellid and Redlichiid faunal provinces are important for determining the timing of the Cambrian radiation. Some authors have argued that there was a hidden radiation that significantly predated the Cambrian, whereas others have suggested that the radiation occurred right at the start of the Cambrian. The results from trilobite biogeography presented here support an early radiation. They are most compatible with the notion that there was a vicariance event relating to the origin of the redlichiinid trilobites, and thus the eponymous Redlichiid faunal province, from the “fallotaspidoids,” whose representatives were part of the Olenellid faunal province. This vicariance event, based on biogeographic patterns, is likely related to the breakup of Pannotia which occurred sometime between 600–550 Ma, suggesting that the initial episodes of trilobite cladogenesis occurred within that interval. As trilobites are relatively derived arthropods, this suggests that Númerous important episodes of metazoan cladogenesis precede both the earliest trilobitic part of the Early Cambrian, and indeed, even the Early Cambrian.

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

Ahlberg, P. 1991. Trilobites in the Lower Cambrian of Scandinavia. Geologiska Föreningens i Stockholm Forhandlingar, 113:7475.CrossRefGoogle Scholar
Ahlberg, P., Bergström, J., and Johansson, J. 1986. Lower Cambrian olenellid trilobites from the Baltic faunal province. Geologiska Föreningens i Stockholm Forhandlingar, 108:3956.CrossRefGoogle Scholar
Archie, J. W. 1989. Homoplasy excess ratios: new indices for measuring levels of homoplasy in phylogenetic systematics and a critique of the consistency index. Systematic Zoology, 38:253269.CrossRefGoogle Scholar
Ayala, F. J., Rzhetsky, A., and Ayala, F. J. 1998. Origin of the metazoan phyla: molecular clocks confirm paleontological estimates. Proceedings of the National Academy of Sciences, U.S.A., 95:606611.CrossRefGoogle ScholarPubMed
Babcock, L. E. 1994. Systematics and phylogenetics of polymeroid trilobites from the Henson Gletscher and Kap Stanton formations (Middle Cambrian), North Greenland. Bulletin Grønlands geologiske Undersøgelse, 169:79127.CrossRefGoogle Scholar
Barnaby, R. J., and Read, J. F. 1990. Carbonate ramp to rimmed shelf evolution: Lower to Middle Cambrian continental margin, Virginia Appalachians. Geological Society of America Bulletin, 102:391404.2.3.CO;2>CrossRefGoogle Scholar
Bergström, J. 1973. Classification of olenellid trilobites and some Bal-to-Scandian species. Norsk Geologisk Tidsskrift, 53:283314.Google Scholar
Bergström, J. 1992. The oldest arthropods and the origin of the Crustacea. Acta Zoologica, 73:287291.CrossRefGoogle Scholar
Bond, G. P., Nickeson, P. A., and Kominz, M. A. 1984. Breakup of a supercontinent between 625 Ma and 555 Ma: new evidence and implications for continental history. Earth and Planetary Science Letters, 70:325345.CrossRefGoogle Scholar
Bremer, K. 1992. Ancestral areas: a cladistic reinterpretation of the center of origin concept. Systematic Biology, 41:436445.CrossRefGoogle Scholar
Bremer, K. 1994. Branch support and tree stability. Cladistics, 10:295304.CrossRefGoogle Scholar
Brooks, D. R., and Mclennan, D. A. 1991. Phylogeny, Ecology, and Behavior. University of Chicago Press, Chicago, 434 p.Google Scholar
Cobbold, E. S. 1935. A new genus of the Trilobita and a new species of the Conchostraca from the Cambrian of the Cateret Region, N. W. France. Annals and Magazine of Natural History, Series 10, 15:381392.CrossRefGoogle Scholar
Dalziel, I. W. D. 1991. Pacific margins of Laurentia and East Antarctica-Australia as a conjugate rift pair: evidence and implications for an Eocambrian supercontinent. Geology, 19:598601.2.3.CO;2>CrossRefGoogle Scholar
Dalziel, I. W. D. 1992. On the organization of American plates in the Neoproterozoic and the breakout of Laurentia. GSA Today, 2:237241.Google Scholar
Dalziel, I. W. D. 1997. Neoproterozoic-Paleozoic geography and tectonics: review, hypothesis, environmental speculation. Geological Society of America Bulletin, 190:1642.2.3.CO;2>CrossRefGoogle Scholar
Darwin, C. 1859. On the Origin of Species by Means of Natural Selection; or the Preservation of Favored Races in the Struggle for Life (Reprinted first edition). Harvard University Press, Cambridge, Massachusetts, 502 p.Google Scholar
Davidson, E. H., Peterson, K. J., and Cameron, R. A. 1995. Origin of bilaterian body plans: evolution of developmental regulatory mechanisms. Science, 270:13191325.CrossRefGoogle ScholarPubMed
Edgecombe, G. D., and Ramsköld, L. 1999. Relationships of Cambrian Arachnata and the systematic position of Trilobita. Journal of Paleontology, 73:263287.CrossRefGoogle Scholar
Faill, R. T. 1997. A geologic history of the north-central Appalachians, Pt. 1, Orogenesis from the Mesoproterozoic through the Taconic Orogeny. American Journal of Science, 297:551619.CrossRefGoogle Scholar
Faith, D. P. 1991. Cladistic permutation tests for monophyly and non-monophyly. Systematic Zoology, 40:366375.CrossRefGoogle Scholar
Faith, D. P., and Trueman, J. W. H. 1996. When the Topology-Dependent Permutation Test (T-PTP) for monophyly returns significant support for monophyly, should that be equated with (a) rejecting a null hypothesis of nonmonophyly, (b) rejecting a null hypothesis of “no structure,” (c) failing to falsify a hypothesis of monophyly, or (d) none of the above? Systematic Biology, 45:580586.CrossRefGoogle Scholar
Fitch, W. M. 1971. Toward defining the course of evolution: minimum change for a specific tree topology. Systematic Zoology, 20:406416.CrossRefGoogle Scholar
Fortey, R. A. 1990. Ontogeny, hypostome attachment and trilobite classification. Palaeontology, 33:529576.Google Scholar
Fortey, R. A. 2001. The Cambrian Explosion exploded? Science, 293:438439.CrossRefGoogle ScholarPubMed
Fortey, R. A., and Cocks, L. R. M. 1992. The early Palaeozoic of the North Atlantic region as a test case for the use of fossils in continental reconstruction. Tectonophysics, 206:147158.CrossRefGoogle Scholar
Fortey, R. A., and Owens, R. M. 1997. Evolutionary history. In Kaesler, R. L. (ed.), Treatise on Invertebrate Paleontology, O (Arthropoda 1, Trilobita, Revised). Geological Society of America and University of Kansas Press, Lawrence, Kansas, p. 249287.Google Scholar
Fortey, R. A., and Theron, J. N. 1994. A new Ordovician arthropod, Soomaspis, and the agnostid problem. Palaeontology, 37:841861.Google Scholar
Fortey, R. A., and Whittington, H. B. 1989. The Trilobita as a natural group. Historical Biology, 2:125138.CrossRefGoogle Scholar
Fortey, R. A., Briggs, D. E. G., and Wills, M. A. 1996. The Cambrian evolutionary ‘explosion’: decoupling cladogenesis from morphological disparity. Biological Journal of the Linnean Society, 57:1333.Google Scholar
Fritz, W. H. 1972. Lower Cambrian trilobites from the Sekwi Formation type section, Mackenzie Mountains, northwestern Canada. Geological Survey of Canada Bulletin, 212:190.Google Scholar
Fritz, W. H. 1992. Walcott's Lower Cambrian olenellid trilobite collection 6IK, Mount Robson area, Canadian Rocky Mountains. Geological Survey of Canada Bulletin, 432:165.Google Scholar
Fritz, W. H. 1993. New Lower Cambrian olenelloid trilobite genera Cirquella and Geraldinella from southwestern Canada. Journal of Paleontology, 67:856868.CrossRefGoogle Scholar
Fritz, W. H. 1995. Esmeraldina rowei and associated Lower Cambrian trilobites (1 f fauna) at the base of Walcott's Waucoban series, southern Great Basin, U.S.A. Journal of Paleontology, 69:708723.CrossRefGoogle Scholar
Geyer, G. 1996. The Moroccan fallotaspidid trilobites revisited. Beringeria, 18:89199.Google Scholar
Geyer, G., and Landing, E. 1995. The Cambrian of Morocco. Beringeria Special Issue 2, 47119.Google Scholar
Geyer, G., and Palmer, A. R. 1995. Neltneriidae and Holmiidae (Trilobita) from Morocco and the problem of Early Cambrian intercontinental correlation. Journal of Paleontology, 69:459474.CrossRefGoogle Scholar
Goryanskii, V. Y., and Egorova, L. I. 1964. O faunenizhnego kembriia severnogosklona Anabarskogoshchita. Uchenye Zapiski, Seriia Paleontologiia i Biostratigrafiia, 4:532.Google Scholar
Gould, S. J. 1989. Wonderful Life. W. W. Norton, New York, 347 p.Google Scholar
Hall, J. 1862. Supplementary note to the thirteenth report of the Regents of the State Cabinet, p. 113119. 15th Annual Report of the New York Cabinet for Natural History, Albany, New York.Google Scholar
Harshman, J. 2001. Does the T-PTP test tell us anything we want to know? Systematic Biology, 50:284289.CrossRefGoogle ScholarPubMed
Hillis, D. M. 1991. Discriminating between phylogenetic signal and random noise in DNA sequences. In Miyamoto, M. M. and Cracraft, J. (eds.), Phylogenetic Analysis of DNA Sequences. Oxford University Press, New York, p. 278294.Google Scholar
Hoffman, P. F. 1991. Did the breakout of Laurentia turn Gondwana inside out? Science, 252:14091412.CrossRefGoogle Scholar
Hollingsworth, J. S. 1999a. The problematical base of the Montezuman stage: should the Laurentian fallotaspidids be in a non-trilobite series? In Palmer, A. R. (ed.), Laurentia 99: V Field Conference of the Cambrian stage Subdivision Working Group. Institute for Cambrian Studies, Boulder, Colorado, p. 59.Google Scholar
Hollingsworth, J. S. 1999b. Stop 10. A candidate position for the base of the Montezuman stage. In Palmer, A. R. (ed.), Laurentia 99: V Field Conference of the Cambrian Stage Subdivision Working Group. Institute for Cambrian Studies, Boulder, Colorado, p. 3437.Google Scholar
Hollingsworth, J. S. 1999c. Stop 12. A second candidate position for the base of the Montezuman stage. In Palmer, A. R. (ed.), Laurentia 99: V field conference of the Cambrian Stage Subdivision Working Group. Institute for Cambrian Studies, Boulder, Colarodo, p. 4246.Google Scholar
Hughes, N. C. 1991. Morphological plasticity and genetic flexibility in a Cambrian trilobite. Geology, 19:913916.2.3.CO;2>CrossRefGoogle Scholar
Hughes, N. C., and Jell, P. A. 1992. A statistical/computer-graphic technique for assessing variation in tectonically deformed fossils and its application to Cambrian trilobites from Kashmir. Lethaia, 25:317330.CrossRefGoogle Scholar
Humphries, C. J., Ladages, P. Y., Roos, M., and Zandee, M. 1988. Cladistic Biogeography. In Myers, A. A. and Giller, P. S. (eds.), Analytical Biogeography. Chapman and Hall, New York City, p. 371404.CrossRefGoogle Scholar
Hupé, P. 1952. Sur les zones de trilobites du Cambrien inferieur marocain. Comptes Rendus de l'Academie des Sciences, Paris, 235:480481.Google Scholar
Hupé, P. 1953. Contributions à l'étude du Cambrien inférieur et du Précambrien III de l'Anti-Atlas marocain. Notes et Mémoires du Service Géologique (Morocco), 103:1402.Google Scholar
Hupé, P., and Abadie, J. 1950. Sur l'existence de Trilobites du Cambrien Inferieur marocain. Comptes Rendus de l'Academie de Sciences, 230:21122113.Google Scholar
Karlstrom, K. E., Williams, M. L., Mclelland, J., Geissman, J. W., and Åhäll, K.-I. 1999. Refining Rodinia: geologic evidence for the Australia-Western U.S. connection in the Proterozoic. GSA Today, 9:17.CrossRefGoogle Scholar
Khomentovskii, V. V., and Repina, L. N. 1965. (The Lower Cambrian stratotype section of Siberia). Sibirskoe Otdelenie, Institut Geologii i Geofiziki, Akademiia Nauk SSSR.Google Scholar
Kir'ianov, V. V., and Chernysheva, N. E. 1967. (About Lower Cambrian deposits of northwestern Volini and the discovery of an ancient trilobite). Izvestiia Akademii Nauk SSSR, Seriia Geologicheskaia, 7:119125.Google Scholar
Klassen, G. J., Mooi, R. D., and Locke, A. 1991. Consistency indices and random data. Systematic Zoology, 40:446457.CrossRefGoogle Scholar
Knoll, A. H. 1996. Daughter of time. Paleobiology, 22:17.CrossRefGoogle ScholarPubMed
Landing, E. 1992. Lower Cambrian of southeastern Newfoundland. In Lipps, J. H. and Signor, P. W. (eds.), Origin and Early Evolution of the Metazoa. Plenum Press, New York, p. 283309.CrossRefGoogle Scholar
Landing, E., Bowring, S. A., Davidek, K. L., Westrop, S. R., Geyer, G., and Heldmaier, W. 1998. Duration of the Early Cambrian: U-Pb ages of volcanic ashes from Avalon and Gondwana. Canadian Journal of Earth Sciences, 35:329338.CrossRefGoogle Scholar
Lermontova, E. V. 1951. (Lower Cambrian trilobites and brachiopods from eastern Siberia). Gosgeolizdat, Moscow, 218 p.Google Scholar
Li, Z.-X., Zhang, L., and Powell, C. McA. 1995. South China in Rodinia: part of the missing link between Australia-East Antarctica and Laurentia? Geology, 23:407410.2.3.CO;2>CrossRefGoogle Scholar
Li, Z.-X., Zhang, L., and Powell, C. McA. 1996. Positions of the East Asian cratons in the Neoproterozoic supercontinent Rodinia. Australian Journal of Earth Sciences, 43:593604.CrossRefGoogle Scholar
Lieberman, B. S. 1997. Early Cambrian paleogeography and tectonic history: a biogeographic approach. Geology, 25:10391042.2.3.CO;2>CrossRefGoogle Scholar
Lieberman, B. S. 1998. Cladistic analysis of the Early Cambrian olenelloid trilobites. Journal of Paleontology, 72:5978.CrossRefGoogle Scholar
Lieberman, B. S. 1999a. Systematic revision of the Olenelloidea (Trilobita, Cambrian). Bulletin of the Yale University Peabody Museum of Natural History, 45:1150.Google Scholar
Lieberman, B. S. 1999b. Testing the Darwinian legacy of the Cambrian radiation using trilobite phylogeny and biogeography. Journal of Paleontology, 73:176181.CrossRefGoogle Scholar
Lieberman, B. S. 2000. Paleobiogeography: Using Fossils to Study Global Change, Plate Tectonics, and Evolution. Kluwer Academic Press/Plenum Publishing, New York, 208 p.CrossRefGoogle Scholar
Lieberman, B. S. 2001. Phylogenetic analysis of the Olenellina Walcott, 1890 (Trilobita, Cambrian). Journal of Paleontology, 75:96115.2.0.CO;2>CrossRefGoogle Scholar
Lieberman, B. S., and Eldredge, N. 1996. Trilobite biogeography in the Middle Devonian: geological processes and analytical methods. Paleobiology, 22:6679.CrossRefGoogle Scholar
Liñan, E., and Sdzuy, K. 1978. A trilobite from the Lower Cambrian of Córdoba (Spain) and its stratigraphical significance. Senckenbergiana Lethaea, 59:387399.Google Scholar
Maddison, W. P., and Maddison, D. R. 1992. MacClade: Analysis of phylogeny and character evolution. Version 3.04. Sinauer Associates, Sunderland, Massachusetts.Google Scholar
McCollum, L. B., and Sundberg, F. A. 1999. Stop 9. Biostratigraphy of the traditional Lower-Middle Cambrian boundary interval in the outer shelf Emigrant Formation, Split Mountain East section, Esmeralda County, Nevada, p. 2931. In Palmer, A. R. (ed.), Laurentia 99: V Field Conference of the Cambrian Stage Subdivision Working Group. Institute for Cambrian Studies, Boulder, Colorado.Google Scholar
McNamara, K. J. 1986. The role of heterochrony in the evolution of Cambrian trilobites. Biological Reviews, 61:121156.CrossRefGoogle Scholar
Moores, E. M. 1991. Southwest U.S.-East Antarctic (SWEAT) connection: a hypothesis. Geology, 19:425428.2.3.CO;2>CrossRefGoogle Scholar
Moyes, A. B., Barton, J. M. Jr., and Groenewald, P. B. 1993. Late Proterozoic to Early Palaeozoic tectonism in Dronning Maud Land, Antarctica: supercontinental fragmentation and amalgamation. Journal of the Geological Sciences, London, 150:833842.CrossRefGoogle Scholar
Nelson, C. A. 1976. Late Precambrian Early Cambrian stratigraphic and faunal succession of eastern California and the Precambrian Cambrian boundary, p. 3140. In Moore, J. N. and Fritsche, A. E. (eds.), Depositional Environments of Lower Paleozoic Rocks in the White Inyo mountains, Inyo County, California. Society of Economic Paleontologists and Mineralogists, Pacific Section, Los Angeles.Google Scholar
Nelson, C. A. 1978. Late Precambrian-Early Cambrian stratigraphic and faunal succession of eastern California and the Precambrian-Cambrian boundary. Geological Magazine, 115:121126.CrossRefGoogle Scholar
Neltner, L., and Poctey, N. 1949. Quelques faunes georgiennes du Maroc. Notes du Service Géologique Maroc, 2, 74:5383.Google Scholar
Palmer, A. R., and Halley, R. B. 1979. Physical stratigraphy and trilobite biostratigraphy of the Carrara Formation (Lower and Middle Cambrian) in the southern Great Basin. U.S. Geological Survey, Professional Paper, 1047:1131.Google Scholar
Palmer, A. R., and Repina, L. N. 1993. Through a glass darkly: taxonomy, phylogeny and biostratigraphy of the Olenellina. University of Kansas Paleontological Contributions, New Series, 3:135.Google Scholar
Palmer, A. R., and Repina, L. N. 1997. Olenellina. In Kaesler, R. (ed.), Treatise on Invertebrate Paleontology, O (Arthropoda 1, Trilobita, Revised). Geological Society of America and University of Kansas Press, Lawrence, Kansas.Google Scholar
Palmer, A. R., and Rowell, A. J. 1995. Early Cambrian trilobites from the Shackleton Limestone of the Central Transantarctic Mountains. Paleontological Society Memoir 45, 69:128.Google Scholar
Pelechaty, S. 1996. Stratigraphic evidence for the Siberia-Laurentia connection and Early Cambrian rifting. Geology, 24:719722.2.3.CO;2>CrossRefGoogle Scholar
Pillola, G. L. 1993. The Lower Cambrian trilobite Bigotina and allied genera. Palaeontology, 36:855881.Google Scholar
Powell, C. McA., Mcelhinny, M. W., Meert, J. G., and Park, J. K. 1993. Paleomagnetic constraints on timing of the Neoproterozoic breakup of Rodinia and the Cambrian formation of Gondwana. Geology, 21:889892.2.3.CO;2>CrossRefGoogle Scholar
Prave, A. R. 1999. Two diamictites, two cap carbonates, two δ13C excursions, two rifts: The Neoproterozoic Kingston Peak Formation, Death Valley, California. Geology, 27:339342.2.3.CO;2>CrossRefGoogle Scholar
Prendini, L. 2001. Species or supraspecific taxa as terminals in cladistic analysis? Groundplans versus exemplars revisited. Systematic Biology, 50:290300.CrossRefGoogle ScholarPubMed
Raff, R. A. 1996. The Shape of Life. University of Chicago Press, Chicago, 520 p.CrossRefGoogle Scholar
Ramsköld, L., and Edgecombe, G. D. 1991. Trilobite monophyly revisited. Historical Biology, 4:267283.CrossRefGoogle Scholar
Raw, F. 1936. Mesonacidae of Comley in Shropshire, with a discussion of classification within the family. Quarterly Journal of the Geological Society of London, 92:236293.CrossRefGoogle Scholar
Ree, R. H., and Donoghue, M. J. 1999. Inferring rates of change in flower symmetry in asterid angiosperms. Systematic Biology, 48:633641.CrossRefGoogle Scholar
Repina, L. N. 1961. (On the discovery of olenellids in the Lena Stage of Batenevskiy Ridge). Doklady Akademii Nauk SSSR, 136:4045.Google Scholar
Repina, L. N. 1979. (Dependence of morphologic features on habitat conditions in trilobites and evaluation of their significance for the systematics of the superfamily Olenelloidea). Akademiia Nauk SSSR, Sibirskoe Otdelenie, Trudy Instituta Geologii i Geofizikii, 431:1130.Google Scholar
Repina, L. N. 1990. (Evolution of trilobites in the beginning stages of their historical development, p. 3444. In Betekina, O. A. and Zhuravleva, I. T. (eds.), (Environment and life of the geologic past). Akademiia Nauk SSSR, Sibirskoe Otdelenie, Trudy Instituta Geologii i Geofizikii 764.Google Scholar
Resser, C. E., and Howell, B. F. 1938. Lower Cambrian Olenellus Zone of the Appalachians. Geological Society of America Bulletin, 49:195248.CrossRefGoogle Scholar
Rice, K. A., Donoghue, M. J., and Olmstead, R. G. 1997. Analyzing large data sets: rbcL 500 revisited. Systematic Biology, 46:554563.CrossRefGoogle ScholarPubMed
Richter, R. 1932. Crustacea (Paläaontologie), p. 840864. In Dittler, R. et al. (eds.), Handwörterbuch der Naturwissenschaften. Gustav Fisher, Jena.Google Scholar
Ronquist, F. 1994. Ancestral areas and parsimony. Systematic Biology, 43:267274.CrossRefGoogle Scholar
Ronquist, F. 1995. Ancestral areas revisited. Systematic Biology, 44:572575.CrossRefGoogle Scholar
Rushton, A. W. A., and Hughes, N. C. 1996. Biometry, systematics and biogeography of the late Cambrian trilobite Maladioidella abdita. Journal of Paleontology, 86:247256.Google Scholar
Sanderson, M. J., and Donoghue, M. J. 1989. Patterns of variation in levels of homoplasy. Evolution, 43:17811795.CrossRefGoogle ScholarPubMed
Sanderson, M. J., Purvis, A., and Henze, C. 1998. Phylogenetic supertrees: assembling the trees of life. Trends in Ecology and Evolution, 13:105109.CrossRefGoogle ScholarPubMed
Scotese, C. 1997. Paleogeographic Atlas. PALEOMAP Project, University of Texas, Arlington, Texas.Google Scholar
Scotese, C., Boucot, A. J., and McKerrow, W. S. 1999. Gondwanan palaeogeography and palaeoclimatology. Journal of African Earth Sciences, 28:99114.CrossRefGoogle Scholar
Sdzuy, K. 1978. The Precambrian-Cambrian boundary beds in Morocco (preliminary report). Geological Magazine, 115:8394.CrossRefGoogle Scholar
Shergold, J. H. 1991. Protaspis and early meraspis growth stages of the eodiscoid trilobite Pagetia ocellata Jell, and their implications for classification. Alcheringa, 15:6586.CrossRefGoogle Scholar
Signore, P. W., and Lipps, J. H. 1992. Origin and early radiation of the Metazoa, p. 323. In Lipps, J. H. and Signor, P. W. (eds.), Origin and Early Evolution of the Metazoa. Plenum Press, New York.CrossRefGoogle Scholar
Stump, E. 1992. The Ross Orogen of the Transantarctic Mountains in light of the Laurentia-Gondwana split. GSA Today, 2:2531.Google Scholar
Swofford, D. L. 1998. PAUP (Phylogenetic analysis using parsimony), version 4.0. Sinauer Associates, Sunderland, Massachusetts.Google Scholar
Swofford, D. L., Thorne, J. L., Felsenstein, J., and Wiegmann, B. M. 1996. The Topology-Dependent Permutation Test for monophyly does not test for monophyly. Systematic Biology, 45:575579.CrossRefGoogle Scholar
Torsvik, T. H., Lohmann, K. C., and Sturt, B. A. 1995. Vendian glaciations and their relation to the dispersal of Rodinia: paleomagnetic constraints. Geology, 23:727730.2.3.CO;2>CrossRefGoogle Scholar
Torsvik, T. H., Smethurst, M. A., Meert, J. G., Van Der Voo, R., Mckerrow, W. S., Brasier, M. D., Sturt, B. A., and Walderhaug, H. J. 1996. Continental break-up and collision in the Neoproterozoic and Palaeozoic-A tale of Baltica and Laurentia. Earth-Science Reviews, 40:229258.CrossRefGoogle Scholar
Unrug, R. 1996. The assembly of Gondwanaland. Episodes, 19:1120.CrossRefGoogle Scholar
Unrug, R. 1997. Rodinia to Gondwana: the geodynamic map of Gondwana supercontinent assembly. GSA Today, 7:17.Google Scholar
Valentine, J. W., Collins, A. G., and Meyer, C. P. 1994. Morphological complexity increase in metazoans. Paleobiology, 20:131142.CrossRefGoogle Scholar
Veevers, J. J., Walter, M. R., and Scheibner, E. 1997. Neoproterozoic tectonics of the Australia-Antarctica and Laurentia and the 560 Ma birth of the Pacific Ocean reflect the 400 m.y. Pangea n supercycle. Journal of Geology, 105:225242.CrossRefGoogle Scholar
Waggoner, B. 1999. Biogeographic analyses of the Ediacara biota: a conflict with paleotectonic reconstructions. Paleobiology, 25:440458.CrossRefGoogle Scholar
Walcott, C. D. 1890. The fauna of the Lower Cambrian or Olenellus Zone. U.S. Geological Survey, 10th Annual Report, 509763.Google Scholar
Walcott, C. D. 1910. Olenellus and other genera of the Mesonacidae. Smithsonian Miscellaneous Collections, 53(6):231422.Google Scholar
Whittington, H. B., Chatterton, B. D. E., Speyer, S. E., Fortey, R. A., Owens, R. M., Chang, W. T., Dean, W. T., Jell, P. A., Laurie, J. R., Palmer, A. R., Repina, L. N., Rushton, A. W. A., Shergold, J. H., Clarkson, E. N. K., Wilmont, N. V., and Kelly, S. R. A. 1997. Part O, Arthropoda 1, Trilobita. Treatise on Invertebrate Paleontology, 1. Geological Society of America and University of Kansas, Boulder, Colorado and Lawrence, KS, 530 p.Google Scholar
Wiens, J. J. 1998. The accuracy of methods for coding and sampling higher-level taxa for phylogenetic analysis: a simulation study. Systematic Biology, 47:397413.CrossRefGoogle ScholarPubMed
Wiley, E. O. 1979. An annotated Linnaean hierarchy, with comments on natural taxa and competing systems. Systematic Zoology, 28:308337.CrossRefGoogle Scholar
Wiley, E. O., Siegel-Causey, D., Brooks, D. R., and Funk, V. A. 1991. The Compleat Cladist. University of Kansas Museum of Natural History Special Publication, 19. University of Kansas Press, Lawrence, Kansas.Google Scholar
Wingate, M. T. D., Campbell, I. H., Compston, W., and Gibson, G. M. 1998. Ion microprobe U-Pb ages for Neoproterozoic basaltic magmatism in south-central Australia and implications for the breakup of Rodinia. Precambrian Research, 87:135159.CrossRefGoogle Scholar
Wray, G. A., Levinton, J. S., and Shapiro, L. H. 1996. Molecular evidence for deep Precambrian divergences among Metazoan phyla. Science, 274:568573.CrossRefGoogle Scholar
Xiao, S., Zhang, Y., and Knoll, A. H. 1998. Three-dimensional preservation of algae and animal embryos in a Neoproterozoic phosphorite. Nature, 351:553558.CrossRefGoogle Scholar
Young, G. M. 1992. Late Proterozoic stratigraphy and the Canada-Australia connection. Geology, 20:215218.2.3.CO;2>CrossRefGoogle Scholar