Terminal addition, the Cambrian radiation and the Phanerozoic evolution of bilaterian form

Evolution and Development

Volumn 7, Issue 6, 2005, Pages 498-514

  Jacobs, David K ^a   Hughes, Nigel C ^b   Fitz Gibbon, Sorel T ^a   Winchell, Christopher J ^a  

^a UNIVERSITY OF CALIFORNIA   (United States)

^b UNIVERSITY OF CALIFORNIA   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

CAMBRIAN; DEVELOPMENTAL BIOLOGY; EVOLUTION; METAZOAN; PHANEROZOIC;

ANIMAL; CONFERENCE PAPER; EVOLUTION; FOSSIL; HUMAN; MORPHOGENESIS;

ANIMALS; BODY PATTERNING; EVOLUTION; FOSSILS; HUMANS;

ANIMALIA; BILATERIA; METAZOA; TRILOBITOMORPHA;

EID: 28244475913     PISSN: 1520541X     EISSN: None     Source Type: Journal    
DOI: 10.1111/j.1525-142X.2005.05055.x     Document Type: Conference Paper

References (146)

1. Aboobaker, A., and Blaxter, M. 2003. Hox gene evolution in nematodes: novelty conserved. Curr. Opin. Gen. Dev. 13: 593-598.
2. Adrianov, A. V., and Malakhov, V. V. 2001. Symmetry of priapulids (Priapulida). 1. Symmetry of adults. J. Morphol. 247: 99-110.
3. Altschul, S. F., Gish, W., Miller, W., Myers, E. W., and Lipman, D. J. 1990. Basic local alignment search tool. J. Mol. Biol. 215: 403-410.
4. Anderson, D. T. 1973. Embryology and Phylogeny in Annelids and Arthropods. Pergamon Press, Oxford.
5. Arenas-Mena, C., Cameron, A. R., and Davidson, E. H. 2000. Spatial expression of Hox cluster genes in the ontogeny of a sea urchin. Development 127: 4631-4643.
6. Aris-Brosou, S., and Yang, Z. H. 2003. Bayesian models of episodic evolution support a late Precambrian explosive diversification of the Metazoa. Mol. Biol. Evol. 20: 1947-1954.
7. Averof, M., and Patel, N. H. 1997. Crustacean appendage evolution associated with changes in Hox gene expression. Nature 388: 682-686.
8. Ayala, F. J. 1999. Molecular clock mirages. Bioessays 21: 71-75.
9. Baba, K. 1940. The early development of a Solenogastre, Epimenia verrucosa (Nierstrasz). Annot. Zool. Jpn. 19: 107-113.
10. Baguña, J., and Riutort, M. 2004. The dawn of bilaterian animals: the case of acoelomorph flatworms. BioEssays 26: 1046-1057.
11. Balavoine, G., and Adoutte, A. 2003. The segmented Urbilateria: a testable scenario. Int. Comp. Biol. 43: 137-147.
12. Barro, O., Vriz, S., Joly, J.-S., Joly, C., Condamine, H., and Boulekbache, H. 1995. Widespread expression of the evel gene in Zebrafish embryos affects the anterior-posterior axis pattern. Dev. Genet. 17: 117-128.
13. Bleidorn, C., Vogt, L., and Bartolomaeus, T. 2003. New insights into polychaete phylogeny (Annelida) inferred from 18S rDNA sequences. Mol. Phylogenet. Evol. 29: 279-288.
14. Blin, M., Rabet, N., Deutsch, J. S., and Mouchel-Vielh, E. 2003. Possible implication of Hox genes Abdominal-B and abdominal-A in the specification of genital and abdominal segments in cirripedes. Dev. Genes Evol. 213: 90-96.
15. Buss, L. W., and Seilacher, A. 1994. The phylum Vendobionta: a sister group of the Eumetazoa. Paleobiology 20: 1-4.
16. Chipman, A. D., Arthur, W., and Akam, M. 2004. A double segment periodicity underlies segment generation in centipede development. Curr. Biol. 14: 1250-1255.
17. Clark, R. B. 1964. Dynamics in Metazoan Evolution: The Origin of the Coelom and Segments. Clarendon Press, Oxford.
18. Cohen, B. L., Holmer, L. E., and Luter, C. 2003. The brachiopod fold: a neglected body plan hypothesis. Palaeontology 46: 59-65.
19. Conway Morris, S., and Peel, J. S. 1990. Articulated halkieriids from the Lower Cambrian of North Greenland. Nature 345: 802-805.
20. Cutler, D. J. 2000. Estimating divergence times in the presence of an overdispersed molecular clock. Mol. Biol. Evol. 17: 1647-1660.
21. Dale, J. K., Maroto, M., Dequeant, M. L., Malapert, P., McGrew, M., and Pourquie, O. 2003. Periodic Notch inhibition by lunatic fringe underlies the chick segmentation clock. Nature 421: 275-278.
22. Damen, W. G. M., Weller, M., and Tautz, D. 2000. The expression patterns of hairy, even-skipped, and runt in the spider Cupiennius salei imply that these genes were segmentation genes in a basal arthropod. Proc. Natl. Acad. Sci. USA 97: 4515-4519.
23. Darwin, C. 1859. On the Origin of Species by Means of Natural Selection. John Murray, London.
24. Davis, D. D. 1949. Comparative anatomy and the evolution of vertebrates. In G. Jepsen, E. Mayr, and G. G. Simpson (eds.). Genetics, Paleontology and Evolution. Princeton University Press, Princeton, pp. 64-89.
25. Davis, G. K., and Patel, N. H. 2002. Short, long, and beyond: molecular and embryological approaches to insect segmentation. Annu. Rev. Entomol. 47: 669-699.
26. Dearden, P. K., and Akam, M. 2001. Early embryo patterning in the grasshopper Schistocerca gregaria: Wingless, decapentaplegic and caudal expression. Development 128: 3435-3444.
27. Decraemer, W., Karanastasi, E., Brown, D., and Backeljau, T. 2003. Review of the ultrastructure of the nematode body cuticle and its phylogenetic interpretation. Biol. Rev. 78: 465-510.
28. Deutsch, J. S., and Mouchel-Vielh, E. 2003. Hox genes and the crustacean body plan. Bioessays 25: 878-887.
29. Dohle, W., and Scholtz, G. 1997. How far does cell lineage influence cell fate specification in crustacean embryos? Semin. Cell Dev. Biol. 8: 379-390.
30. Dong, X. P., Donoghue, P. C. J., Cheng, H., and Liu, J. B. 2004. Fossil embryos from the Middle and Late Cambrian period of Hunan, South China. Nature 427: 237-240.
31. Enghoff, H., Dohle, W., and Blower, J. G. 1993. Anamorphosis in millipedes (Diplopoda). The present state of knowledge and phylogenetic considerations. Zool. J. Linn. Soc. 109: 103-234.
32. Fedonkin, M. A., and Waggoner, B. M. 1997. The Late Precambrian fossil Kimberella is a mollusc-like bilaterian organism. Nature 388: 868-871.
33. Ferrier, D. E. K., Minguillon, C., Cebrian, C., and Garcia-Fernandez, J. 2001. Amphioxus Evx genes: implications for the evolution of the midbrain-hindbrain boundary and the chordate tailbud. Dev. Biol. 237: 270-281.
34. Finnerty, J. R., Pang, K., Burton, P., Paulson, D., and Martindale, M. Q. 2004. Origins of bilateral symmetry: hox and dpp expression in a sea anemone. Science 304: 1335-1337.
35. Foote, M. 1999. Morphological diversity in the evolutionary radiation of Paleozoic and post-Paleozoic crinoids. Palaeobiology 25 (suppl.): 1-115.
36. Friedrich, S., Wanninger, A., Bruckner, M., and Haszprunar, G. 2002. Neurogenesis in the mossy chiton, Mopalia muscosa (Gould) (Polyplacophora): evidence against molluscan metamerism. J. Morphol. 253: 109-117.
37. Freeman, G. 2003. Regional specification during embryogenesis in Rhynchonelliform brachiopods. Dev. Biol. 261: 268-287.
38. Freeman, G., and Martindale, M. Q. 2002. The origin of mesoderm in phoronids. Dev. Biol. 252: 301-311.
39. Fusco, G. 2005. Trunk segment numbers and sequential segmentation in myriapods. Evol. Dev. 7: 608-617.
40. Fusco, G., Hughes, N. C., Webster, M., and Minelli, A. 2004. Exploring developmental modes in a fossil arthropod: growth and trunk segmentation of the trilobite Aulacopleura konincki. Am. Nat. 163: 167-183.
41. Gad, G. 2005. A parthenogenetic, simplifed adult in the life cycle of Pliciloricus pedicularis sp. n. (Loricifera) from the deep sea of the Angola Basin (Atlantic). Org. Div. Evol. 5 (suppl. 1): 77-103.
42. Gaunt, S. J. 2000. Evolutionary shifts of vertebrate structures and Hox expression up and down the axial series of segments: a consideration of possible mechanisms. Int. J. Dev. Biol. 44: 109-117.
43. Gehling, J. G. 1991. The case for Ediacaran fossil roots to the metazoan tree. Geol. Soc. India Mem. 20: 181-224.
44. Glaessner, M. F. 1984. The Dawn of Animal Life. Cambridge University Press, Cambridge.
45. Glaessner, M. F., and Wade, M. 1971. Praecambridium a primitive arthropod. Lethaia 4: 71-77.
46. Graur, D., and Martin, W. 2004. Reading the entrails of chickens: molecular timescales of evolution and the illusion of precision. Trends Genet. 20: 80-86.
47. Gu, X. 1998. Early metazoan divergence was about 830 million years ago. J. Mol. Evol. 47: 369-371.
48. Halanych, K. M. 2004. The new view of animal phylogeny. Ann. Rev. Ecol. Evol. Syst. 35: 229-256.
49. Hejnol, A., and Schnabel, R. 2005. The eutardigrade Thulinia stephaniae has an indeterminate development and the potential to regulate early blastomere ablations. Development 132: 1349-1361.
50. Henry, J. J., and Martindale, M. Q. 1998. Conservation of the spiralian developmental program: cell lineage of the nemertean, Cerebratulus lacteus. Dev. Biol. 201: 253-269.
51. Hessling, R., and Westheide, W. 2002. Are Echiura derived from a segmented ancestor? Immunohistochemical analysis of the nervous system in developmental stages of Bonellia viridis. J. Morphol. 252: 100-113.
52. Holmer, L. E., Skovsted, C. B., and Williams, A. 2002. A stem group brachiopod from the Lower Cambrian: support for a Micrina (halkieriid) ancestry. Paleontology 45: 875-882.
53. Hughes, N. C. 2003a. Trilobite body patterning and the evolution of arthropod tagmosis. BioEssays 25: 386-395.
54. Hughes, N. C. 2003b. Trilobite tagmosis and body patterning from morphological and developmental perspectives. Integr. Comp. Biol. 43: 185-206.
55. Hughes, N. C. Trilobite construction: building a bridge across the micro-and macroevolutionary divide. In D. E. G. Briggs (ed.). Evolving Form and Function: Fossils and Development: Proceedings of a Symposium Honoring Adolph Seilacher for his Contributions to Paleontology, in Celebration of his 80th Birthday. Yale Peabody Museum Special Papers, in press.
56. Hughes, N. C., Chapman, R. E., and Adrain, J. M. 1999. The stability of thoracic segmentation in trilobites: a case study in developmental and ecological constraints. Evol. Dev. 1: 24-35.
57. Hughes, C. L., and Kaufman, T. C. 2002a. Exploring myriapod segmentation: the expression patterns of even-skipped, engrailed, and wingless in a centipede. Dev. Biol. 247: 47-61.
58. Hughes, C. L., and Kaufman, T. C. 2002b. Hox genes and the evolution of the arthropod body plan. Evol. Dev. 4: 459-499.
59. Irvine, S. Q., and Martindale, M. Q. 2000. Expression patterns of anterior Hox genes in the polychaete Chaetopterus: correlation with morphological boundaries. Dev. Biol. 217: 333-351.
60. Ivantsov, A. Y. 2001. Vendia and other Precambrian "arthropods. " Paleontol. J. 35: 335-343.
61. Jacobs, D. K. 1986. Homeotic complexes and segment specification in arthropod evolution. Society for Study of Evolution, Annual Meeting, Program, p. 20.
62. Jacobs, D. K. 1987. Homeotic mutants and the higher metazoan bauplan: inferences in phylogeny, evolution and paleontology. Geol. Soc. Am. Abstr. Programs 19: 714.
63. Jacobs, D. K. 1990. Selector genes and the Cambrian radiation of the Bilateria. Proc. Natl. Acad. Sci. USA 87: 4406-4410.
64. Jacobs, D. K. 2002. Biases and biology produce spurious early molecular divergence dates for the metazoan radiation-a test by outgroup comparison. Geol. Soc. Am. Annu. Meeting Abstr. Programs 39: A207.
65. Jacobs, D. K., and Gates, R. D. 2003. Developmental genes and the reconstruction of metazoan evolution: implications of evolutionary loss, limits on inference of ancestry and type 2 errors. Int. Comp. Biol. 43: 619-646.
66. Jacobs, D. K., Lee, S. E., Dawson, M. N., Staton, J. L., and Raskoff, K. A. 1998. The history of development through the evolution of molecules: gene trees, hearts, eyes, and dorsoventral inversion. In R. DeSalle and B. Schierwater (eds.). Molecular Approaches to Ecology and Evolution. Birkhauser Verlag, Basel, pp. 323-357.
67. Jacobs, D. K., et al. 2000. Molluscan engrailed expression, serial organization and shell evolution. Evol. Dev. 2: 340-347.
68. Jennings, R. M., and Halanych, K. M. 2005. Mitochondrial genomes of Clymenella torquata (Maldanidae) and Riftia pachyptila (Siboglinidae): evidence for conserved gene order in Annelida. Mol. Biol. Evol. 22: 210-222.
69. Joly, J.-S., Maury, M., Joly, C., Duprey, P., Boulekbache, H., and Condamine, H. 1992. Expression of a zebrafish caudal homeobox gene correlates with the establishment of posterior cell lineages at gastrulation. Differentiation 50: 75-87.
70. Katsuyama, Y., Sato, Y., Wada, S., and Saiga, H. 1999. Ascidian tail formation requires caudal function. Dev. Biol. 213: 257-268.
71. Kniprath, E. 1980. Ontogenetic plate and plate field development in two chitons, Middendorffia and Ischnochiton. Roux's Arch. Dev. Biol. 189: 97-106.
72. Knoll, A. H. 2000. Learning to tell Neoproterozoic time. Precambrian Res. 100: 3-20.
73. Knoll, A. H., Walter, M. R., Narbonne, G. M., and Christie-Blick, N. 2004. A new period for the geologic time scale. Science 305: 621-622.
74. Lee, P. N., Callaerts, P., de Couet, H. G., and Martindale, M. Q. 2003. Cephalopod Hox genes and the origin of morphological novelties. Nature 424: 1061-1065.
75. Lefebvre, B. 2003. Functional morphology of stylophoran echinoderms. Palaeontology 46: 511-555.
76. Lowe, C. J., and Wray, G. A. 1997. Radical alterations in the roles of homeobox genes during echinoderm evolution. Nature 389: 718-721.
77. Lowe, C. J., et al. 2003. Anteroposterior patterning in hemichordates and the origins of the chordate nervous system. Cell 113: 853-865.
78. Mahaffey, J. W., Diederich, R. J., and Kaufman, T. C. 1989. Novel patterns of homeotic protein accumulation in the head of the Drosophila embryo. Development 105: 167-174.
79. Manuel, M., Le Parco, Y., and Borchiellini, C. 2004. Comparative analysis of Brachyury T-domains, with the characterization of two new sponge sequences from, a hexactinellid and a calcisponge. Gene 340 (2): 291-301.
80. Mayer, G., Bartolomaeus, T., and Ruhberg, H. 2005. Ultrastructure of mesoderm in embryos of Opisthopatus roseus (Onychophora, Peripatopsidae): revision of the "long germ band" hypothesis for Opisthopatus. J. Morphol. 263: 60-70.
81. McHugh, D. 2000. Molecular phylogeny of the Annelida. Can. J. Zool. 78: 1873-1884.
82. McKinney, M. L., and McNamara, K. K. 1991. Heterochrony: The Evolution of Ontogeny. Plenum Press, New York.
83. McNamara, K. J. 1983. Progenesis in trilobites. Spec. Pap. Palaeontol. 30: 59-68.
84. Medina, M., Collins, A. G., Silberman, J. D., and Sogin, M. L. 2001. Evaluating hypotheses of basal animal phytogeny using complete sequences of large and small subunit rRNA. Proc. Natl. Acad. Sci. USA 98: 9707-9712.
85. Metscher, B. D., Takahashi, K., Crow, K., Amemiya, C., Nonaka, D. F., and Wagner, G. P. 2005. Expression of Hoxa-11 and Hoxa-13 in the pectoral fin of a basal ray-finned fish, Polyodon spathula: implications for the origin of tetrapod limbs. Evol. Dev. 7: 186-195.
86. Minelli, A., and Bortoletto, S. 1988. Myriapod metamerism and arthropod segmentation. Biol. J. Linn. Soc. 33: 323-343.
87. Minelli, A., and Fusco, G. 2004. Evo-devo perspectives on segmentation: model organisms, and beyond. Trends Ecol. Evol. 19: 423-429.
88. Minelli, A., Fusco, G., and Hughes, N. C. 2003. Tagmata and segment specification in trilobites. Spec. Pap. Palaeontol. 70: 31-43.
89. Mooi, R., David, B., and Wray, G. A. 2005. Arrays in rays: terminal addition in echinoderms and its correlation with gene expression. Evol. Dev. 7: 542-555.
90. Moreno, E., and Morata, G. 1999. caudal is the Hox gene that specifies the most posterior Drosophila segment. Nature 400: 873-877.
91. Muller, M., Weizsacker, E., and Campos-Ortega, J. A. 1996. Expression domains of a zebrafish homologue of the Drosophila pair-rule gene hairy correspond to primordia of alternating somites. Development 122: 2071-2078.
92. Muller, M. C. M., Jochmann, R., and Schmidt-Rhaesa, A. 2004. The musculature of horsehair worm larvae (Gordius aquaticus, Paragordius varius, Nematomorpha): F-actin staining and reconstruction by cLSM and TEM. Zoomorphology 123: 45-54.
93. Narbonne, G. M. 2004. Modular construction of early Ediacaran complex life forms. Science 305: 1141-1144.
94. Nebelsick, M. 1993. Introvert, mouth cone, and nervous system of Echinoderes capitatus (Kinorhyncha, Cyclorhagida) and implication for the phylogenetic relationships of kinorhyncha. Zoomorphology 113: 211-232.
95. Nei, M., Xu, P., and Glazko, G. 2001. Estimation of divergence times from multiprotein sequences for a few mammalian species and several distantly related organisms. Proc. Natl. Acad. Sci. USA 98: 2497-2502.
96. Neuhaus, B. 1995. Postembryonic development of Paracentrophyes praedictus (Homalorharida): neoteny questionable among the Kinorhyncha. Zool. Scripta 24: 179-192.
97. Neuhaus, B., and Higgins, R. P. 2002. Ultrastructure, biology, and phylogenetic relationships of Kinorhyncha. Int. Comp. Biol. 42: 619-632.
98. Newby, W. W. 1902. The embryology of the echiuroid worm Urechis caupo. Mem. Am. Philos. Soc. 16: 1-219.
99. Palmeirim, I., Henrique, D., Ish-Horowicz, D., and Pourquié, O. 1997. Avian hairy gene expression identifies a molecular clock linked to vertebrate segmentation and somitogenesis. Cell 91: 639-648.
100. Patel, N. H., Condron, B. G., and Zinn, K. 1994. Pair-rule expression patterns of even-skipped are found in both short and long germ beetles. Nature 367: 429-434.
101. Patel, N. H., Kornberg, T. B., and Goodman, C. S. 1989. Expression of engrailed during segmentation in grasshopper and crayfish. Development 107: 201-212.
102. Paterson, J. R., and Edgecombe, G. D. The early Cambrian trilobite family Emuellidae Pocock, 1970. Systematic position and revision of Australian species. J. Paleontol., in press.
103. Peel, J. S. 1991. Functional morphology, evolution and systematics of Early Palaeozoic univalved molluscs. Bull. Grønlands Geol. Unders. 161: 1-116.
104. Peterson, K. J., Lyons, J. B., Nowak, K. S., Takacs, C. M., Wargo, M. J., and McPeek, M. A. 2004. Estimating metazoan divergence times with a molecular clock. Proc. Natl. Acad. Sci. USA 101: 6536-6541.
105. Petrov, D. A., Sangster, T. A., Johnston, J. S., Hartl, D. L., and Shaw, K. L. 2000. Evidence for DNA loss as a determinant of genome size. Science 287: 1060-1062.
106. Pilger, J. F. 1997. Sipunculans and Echiurans. In S. F. Gilbert and A. M. Raunio (eds.). Embryology: Constructing the Organism. Sinauer Associates, Sunderland, MA, pp. 167-188.
107. Pourquié, O. 2003. The segmentation clock: converting embryonic time into spatial pattern. Science 301: 328-330.
108. Prud'homme, B., et al. 2003. Arthropod-like expression patterns of engrailed and wingless in the annelid Platynereis dumerilii suggest a role in segment formation. Curr. Biol. 13: 1876-1881.
109. Raff, R. A., and Kaufman, T. C. 1983. Embryos, Genes, and Evolution. Macmillan, New York.
110. Raymond, P. E. 1920. The appendages, anatomy, and relationships of trilobites. Mem. Connecticut Acad. Sci. 7: 1-169.
111. Rivera, A. S., Gonsalves, F. C., Song, M. H., Norris, B. J., and Weisblat, D. A. 2005. Characterization of Notch-class gene expression in segmentation stem cells and segment founder cells in Helobdella robusta (Lophotrochozoa; Annelida; Clitellata; Hirudinida; Glossiphoniidae). Evol. Dev. 7: 588-599.
112. Rouse, G. W., and Pleijel, F. 2001. Polychaetes. Oxford University Press, Oxford.
113. Ruiz-Trillo, I., Riutort, M., Fourcade, H. M., Baguna, J., and Boore, J. L. 2004. Mitochondrial genome data support the basal position of Acoelomorpha and the polyphyly of the Platyhelminthes. Mol. Phylogenet. Evol. 33: 321-332.
114. Runnegar, B. N. 1995. Vendobionta or Metazoa? Developments in understanding the Ediacra "fauna". Neues Jahrb. Geol. Palaeontolo. Abh. 195: 303-318.
115. Schoppmeier, M., and Damen, W. G. 2005. Suppressor of Hairless and Presenilin phenotypes imply involvement of canonical Notch-signalling in segmentation of the spider Cupiennius salei. Dev. Biol. 280: 211-224.
116. Schram, F. R. 1986. Crustacea. Oxford University Press, New York.
117. Schubert, M., Holland, L. Z., Holland, N. D., and Jacobs, D. K. 2000. A phylogenetic tree of the Wnt genes based on all available full-length sequences, including five from the cephalochordate Amphioxus. Mol. Biol. Evol. 17: 1896-1903.
118. Scholtz, G., Patel, N. H., and Dohle, W. 1994. Serially homologous engrailed stripes are generated via different cell lineages in the germ band of amphipod crustaceans (Malacostraca, Peracarida). Int. J. Dev. Biol. 38: 471-478.
119. Schulz, C., Schroeder, R., Hausdorf, B., Wolff, C., and Tautz, D. 1998. A caudal homologue in the short germ band beetle Tribolium shows similarities to both the Drosophila and the vertebrate caudal expression patterns. Dev. Genes Evol. 208: 283-289.
120. Seilacher, A. 1984. Late Precambrian and Early Cambrian Metazoa: preservational or real extinctions? In H. D. Holland and A. F. Trendall (eds.). Patterns of Change in Earth Evolution. Dahlem Konferenzen. Springer, Berlin, pp. 159-168.
121. Seilacher, A. 1989. Vendozoa: organismic construction in the Proterozoic biosphere. Lethaia 22: 229-239.
122. Seo, H.-C., et al. 2001. Miniature genome in the marine chordate Oikopleura dioica. Science 294: 2506.
123. Sepkoski, J. J. 1981. A factor analytic description of the Phanerozoic marine fossil record. Paleobiology 7: 36-53.
124. Simonnet, F., Deutsch, J., and Queinnec, E. 2004. hedgehog is a segment polarity gene in a crustacean and a chelicerate. Dev. Genes Evol. 214: 537-545.
125. Smith, A. B., and Peterson, K. J. 2002. Dating the time of origin of major clades: molecular clocks and the fossil record. Annu. Rev. Earth Planet. Sci. 30: 65-88.
126. Sommer, R. J., and Tautz, D. 1993. Involvement of an orthologue of the Drosophila pair-rule gene hairy in segment formation of the short germ-band embryo of Tribolium (Coleoptera). Nature 361: 448-450.
127. Song, M. H., Huang, F. Z., Chang, G. Y., and Weisblat, D. A. 2002. Expression and function of an even-skipped homolog in the leech Helobdetta robusta. Development 129: 3681-3692.
128. Song, M. H., Huang, F. Z., Gonsalves, F. C., and Weisblat, D. A. 2004. Cell cycle-dependent expression of a hairy and Enhancer of split (hes) homolog during cleavage and segmentation in leech embryos. Dev. Biol. 269: 183-195.
129. Stollewerk, A., Schoppmeier, M., and Damen, W. G. M. 2003. Involvement of Notch and Delta genes in spider segmentation. Nature 423: 863-865.
130. Sutton, M. D., Briggs, D. E. G., Siveter, D. J., and Siveter, D. J. 2001. An exceptionally preserved vermiform mollusc from the Silurian of England. Nature 410: 461-463.
131. Sutton, M. D., Briggs, D. E. G., Siveter, D. J., and Siveter, D. J. 2004. Computer reconstruction and analysis of the vermiform mollusc Acaenoplax hayae from the Herefordshire lagerstatte (Silurian, England), and implications for molluscan phylogeny. Palaeontology 47: 293-318.
132. Telford, M. J., Wise, M. J., and Gowri-Shankar, V. 2005. Consideration of RNA secondary structure significantly improves likelihood-based estimates of phylogeny: examples from the Bilateria. Mol. Biol. Evol. 22: 1129-1136.
133. Vendrasco, M. J., Wood, T. E., and Runnegar, B. N. 2004. Articulated Palaeozoic fossil with 17 plates greatly expands disparity of early chitons. Nature 429: 288-291.
134. Vermeij, G. J. 1973. The Mesozoic marine radiation: evidence from snails, predators and grazers. Paleobiology 3: 245-248.
135. Wade, M. 1972. Dickinsonia: polychaete worms from the late Precambrian Ediacaran fauna, South Australia. Mem. Queensland Mus. 16: 171-190.
136. Walker, M. H. 1995. Relatively recent evolution of an unusual pattern of early embryonic development (long germ band?) in a South African onychophoran, Opisthopatus cinctipes Purcell (Onychophora: Peripatopsidae). Zool. J. Linn. Soc. 114: 61-75.
137. Wallberg, A., Thollesson, M., Farris, J. S., and Jondelius, U. 2004. The phylogenetic position of the comb jellies (Ctenophora) and the importance of taxonomic sampling. Cladistics 20: 558-578.
138. Wang, D. Y.-C, Kumar, S., and Hedges, S. B. 1999. Divergence time estimates for the early history of animal phyla and the origin of plants, animals and fungi. Proc. R. Soc. London. Ser. B 266: 163-171.
139. Warwick, R. M. 2000. Are loriciferans paedomorphic (progenetic) priapulids? Vie Milieu 50: 191-193.
140. Weisblat, D. A., and Shankland, M. 1985. Cell lineage and segmentation in the leech. Philos. Trans. R. Soc. London B. Biol. Sci. 312: 39-56.
141. Whittington, H. B., and Evitt, W. R. 1953. Silicified Middle Ordovician trilobites. Geol. Soc. Am. Mem. 59: 1-137.
142. Willmer, P. 1990. Invertebrate Relationships: Patterns in Animal Evolution. Cambridge University Press, Cambridge.
143. Wingstrand, K. G. 1985. On the anatomy and relationships of recent Monoplacophora. Galathea Rep. 16: 7-94.
144. Wray, G. A., Levinton, J. S., and Shapiro, L. H. 1996. Molecular evidence for deep Precambrian divergences among metazoan phyla. Science 274: 568-573.
145. Wu, L. H., and Lengyel, J. A. 1998. Role of caudal in hindgut specification and gastrulation suggests homology between Drosophila amnioproctodeal invagination and vertebrate blastopore. Development 125: 2433-2442.
146. Zimmer, R. 1997. Phoronids, brachiopods, and bryzoans, the lophophorates. In S. F. Gilbert and A. M. Raunio (eds.). Embryology: Constructing the Organism. Sinauer Associates, Sunderland, MA, pp. 279-308.