The quality of the fossil record: Implications for evolutionary analyses

Annual Review of Ecology and Systematics

Volumn 33, Issue , 2002, Pages 561-588

  Kidwell, Susan M ^a   Holland, Steven M ^b  

^a UNIVERSITY OF CHICAGO   (United States)

^b UNIVERSITY OF GEORGIA   (United States)

Author keywords

Extinction; Paleobiology; Phylogeny; Speciation; Stratigraphy; Taphonomy

Indexed keywords

EXTINCTION; FOSSIL RECORD; PHYLOGENY; SPECIATION (BIOLOGY); STRATIGRAPHY; TAPHONOMY;

EID: 0036909622     PISSN: 00664162     EISSN: None     Source Type: Journal    
DOI: 10.1146/annurev.ecolsys.33.030602.152151     Document Type: Review

References (140)

1. Allison PA, Briggs DEG, eds. 1991. Taphonomy: Releasing the Data Locked in the Fossil Record. New York: Plenum
2. Allison PA, Briggs DEG. 1993a. Exceptional fossil record: Distribution of soft-tissue preservation through the Phanerozoic. Geology 21:527-30
3. Allison PA, Briggs DEG. 1993b. Paleolatitudinal sampling bias, Phanerozoic species diversity, and the end-Permian extinction. Geology 21:65-68
4. Alroy J, Marshall CR, Bambach RK, Bezusko K, Foote M, et al. 2001. Effects of sampling standardization on estimates of Phanerozoic marine diversification. Proc. Natl. Acad. Sci. USA 98:6261-66
5. Anders MH, Krueger SW, Sadler PM. 1987. A new look at sedimentation rates and the completeness of the stratigraphic record. J. Geol. 95:1-14
6. Anderson LC, Sen Gupta BK, McBride RA, Byrnes MR. 1997. Reduced seasonality of Holocene climate and pervasive mixing of Holocene marine section: Northeastern Gulf of Mexico shelf. Geology 25:127-30
7. Bada JL, Wang XS, Hamilton H. 1999. Preservation of key biomolecules in the fossil record: Current knowledge and future challenges. Philos. Trans. R. Soc. London Ser. B 354:77-87
8. Baumiller TK. 1996. Exploring the pattern of coordinated stasis: Simulations and extinction scenarios. Palaeogeogr. Palaeoclimatol. Palaeoecol. 127:135-46
9. Bayer U, McGhee GR. 1985. Evolution in marginal epicontinental basins: The role of phylogenetic and ecologic factors (Ammonite replacements in the German Lower and Middle Jurassic). In Sedimentary and Evolutionary Cycles, ed. U Bayer, A Seilacher, pp. 164-220. New York: Springer-Verlag
10. Behrensmeyer AK. 1999. Bonebeds through geologic time. J. Vertebr. Paleontol. 19(Suppl. to 3):31-32A
11. Behrensmeyer AK, Chapman RE. 1993. Models and Simulations of Time-averaging in Terrestrial Vertebrate Accumulations. See Kidwell & Behrensmeyer 1993, pp. 125-49
12. Behrensmeyer AK, Dechant Boaz DE. 1980. The recent bones of Amboseli Park, Kenya, in relation to East African paleoecology. In Fossils in the Making, ed. AK Behrensmeyer, AP Hill, pp. 72-92. Chicago, IL: Univ. Chicago Press
13. Behrensmeyer AK, Hook RW. 1992. Paleoenvironmental contexts and taphonomic modes in the terrestrial fossil record. In Terrestrial Ecosystems Through Time, ed. AK Behrensmeyer, JD Damuth, WA DiMichele, R Potts, H-D Sues, SL Wing, pp. 15-136. Chicago, IL: Univ. Chicago Press
14. Behrensmeyer AK, Kidwell SM, Gastaldo RA. 2000. Taphonomy and Paleobiology. See Erwin & Wing 2000, pp. 103-47
15. Behrensmeyer AK, Todd NE, Potts R, McBrinn GE. 1997. Late Pliocene faunal turnover in the Turkana Basin, Kenya and Ethiopia. Science 278:1589-94
16. Bell MA, Sadagursky MS, Baumgartner JV. 1987. Utility of lacustrine deposits for the study of variation within fossil samples. Palaios 2:455-66
17. Berggren WA, Kent DV, Swisher III CC, Aubry MP. 1995. A revised Cenozoic geochronology and chronostratigraphy. In Geochronology, Time Scales and Global Stratigraphic Correlation, ed. WA Berggren, DV Kent, MP Aubry, J Hardenbol, pp. 129-212. Tulsa, OK: SEPM Spec. Publ. No. 54
18. Bowring SA, Erwin DH. 1998. A new look at evolutionary rates in deep time: Uniting paleontology and high-precision geochronology. Geol. Soc. Am. Today 8:1-8
19. Bowring SA, Grotzinger JP, Isachsen CE, Knoll AH, Pelechaty SM, Kolosov P. 1993. Calibrating rates of early Cambrian evolution. Science 261:1293-98
20. Brett CE. 1995. Sequence stratigraphy, biostratigraphy, and taphonomy in shallow marine environments. Palaios 10:597-616
21. Brett CE, Baird GC. 1995. Coordinated Stasis and Evolutionary Ecology of Silurian to Middle Devonian Faunas in the Appalachian Basin. See Erwin & Anstey 1995, pp. 285-315
22. Brewster-Wingard GL, Stone JR, Holmes CW. 2001. Molluscan faunal distribution in Florida Bay, past and present: An integration of down-core and modern data. Bull. Am. Paleontol. 361:199-231
23. Briggs DEG, Crowther PR, eds. 2001. Paleobiology II. Oxford: Blackwell Sci. 583 pp.
24. Bush AM, Powell MG, Arnold WS, Bert TM, Daley GM. 2002. Time-averaging, evolution, and morphologic variation. Paleobiology 28:9-250
25. Chapman MR. 2000. The Response of Planktonic Foraminifera to the Late Pliocene Intensification of Northern Hemisphere Glaciation. See Culver & Rawson, pp. 79-96
26. Cisne JL, Chandlee GO, Rabe BD, Cohen JA. 1982. Clinal variation, episodic evolution, and possible parapatric speciation: The trilobite Flexicalymene senaria along an Ordovician depth gradient. Lethaia 15:325-41
27. Cisne JL, Molenock J, Rabe BD. 1980. Evolution in a cline: The trilobite Triarthrus along an Ordovician depth gradient. Lethaia 13:47-59
28. Cohen AS. 1989. The taphonomy of gastropod shell accumulations in large lakes: An example from Lake Tanganyika, Africa. Paleobiology 15:26-45
29. Connolly SR, Miller AI. 2001. Joint estimation of sampling and turnover rates from fossil databases: Capture-mark-recapture methods revisited. Paleobiology 27:751-67
30. Cooper A, Poinar HN. 2000. Ancient DNA: Do it right or not at all. Science 289:1139
31. Copper P. 2001. Reefs during the multiple crises towards the Ordovician-Silurian boundary: Anticosti Island, eastern Canada, and worldwide. Can. J. Earth Sci. 38:153-71
32. Culver SJ, Rawson PF. 2000. Biotic Response to Global Change, the Last 145 Million Years. 501 pages. Cambridge, UK: Cambridge Univ. Press
33. Daley GM. 1999. Environmentally controlled variation in shell size of Ambonychia Hall (Mollusca: Bivalvia) in the type Cincinnatian (Upper Ordovician). Palaios 14:520-29
34. Davis MB. 2000. Palynology after Y2K - Understanding the source area of pollen in sediments. Annu. Rev. Ecol. Syst. 28:1-18
35. Donovan SK, Paul CRC. 1998. The Adequacy of the Fossil Record. Chichester: Wiley & Sons. 312 pp.
36. Dowsett HJ. 1988. Diachrony of late Neogene microfossils in the southwest Pacific Ocean: Application off the graphic correlation technique. Paleoceanography 3:209-22
37. Erwin DH, Anstey RL, eds. 1995. New Approaches to Speciation in the Fossil Record. New York: Columbia Univ. Press
38. Erwin DH, Wing SL, eds. 2000. Deep Time: Paleobiology's Perspective. Lawrence, KS: Paleontol. Soc.
39. Fisher DC. 1994. Stratocladistics: Morphological and temporal patterns and their relation to phylogenetic process. In Interpreting the Hierarchy of Nature, ed. L Grande, O Rieppel, pp. 133-71. San Diego, CA: Academic
40. Flessa KW. 1998. Well-traveled cockles: Shell transport during the Holocene transgression of the southern North Sea. Geology 26:187-90
41. Flessa KW, Kowalewski M. 1994. Shell survival and time-averaging in nearshore and shelf environments: Estimates from the radiocarbon literature. Lethaia 27:153-65
42. Foote M. 1996. On the probability of ancestors in the fossil record. Paleobiology 22:141-51
43. Foote M. 1997. The evolution of morphological diversity. Annu. Rev. Ecol. Syst. 28:129-52
44. Foote M. 2001. Inferring temporal patterns of preservation, origination, and extinction from taxonomic survivorship analysis. Paleobiology 27:602-30
45. Foote M. 2003. Origination and extinction through the Phanerozoic: A new approach. J. Geol. 111: In press
46. Foote M, Hunter JP, Janis CM, Sepkoski JJ Jr. 1999. Evolutionary and preservational constraints on origins of biologic groups: Divergence times of eutherian mammals. Science 283:1310-14
47. Fortey RA. 1985. Gradualism and punctuated equilibria as competing and complementary series. Spec. Pap. Palaeontol. 33:17-28
48. Fürsich FT. 1978. The influence of faunal condensation and mixing on the preservation of fossil benthic communities. Lethaia 11:243-50
49. Gingerich PD. 1979. The stratophenetic approach to phylogeny reconstruction in vertebrate paleontology. In Phylogenetic Analysis and Paleontology, ed. J Cracraft, N Eldredge, pp. 41-77. New York: Columbia Univ. Press
50. Goldman D, Mitchell CE, Joy MP. 1999. The stratigraphic distribution of graptolites in the classic upper Middle Ordovician Utica Shale of New York State: An evolutionary succession or a response to relative sea-level change? Paleobiology 25:273-94
51. Graham RW. 1993. Processes of time-averaging in the terrestrial vertebrate record. See Kidwell & Behrensmeyer 1993, pp. 102-24
52. Heckman DS, Geiser DM, Eidell BR, Stauffer RL, Kardos NL, Hedges SB. 2001. Molecular evidence for the early colonization of land by fungi and plants. Science 293:1129-33
53. Hinnov LA. 2000. New perspectives on orbitally forced stratigraphy. Annu. Rev. Earth Planet. Sci. 28:419-75
54. Holland SM. 1995. The stratigraphic distribution of fossils. Paleobiology 21:92-109
55. Holland SM. 1996. Recognizing artifactually generated coordinated stasis: Implications of numerical models and strategies for field tests. Palaeogeogr. Palaeoclimatol. Palaeoecol. 127:147-56
56. Holland SM. 2000. The Quality of the Fossil Record - A Sequence Stratigraphic Perspective. See Erwin & Wing 2000, pp. 148-68
57. Holland SM. 2001. Confidence limits on fossil ranges that account for sequence architecture. Geol. Soc. Am. Abstr. Program 33:A31
58. Holland SM, Patzkowsky ME. 1999. Models for simulating the fossil record. Geology 27:491-94
59. Holland SM, Patzkowsky ME. 2002. Stratigraphic variation in the timing of first and last occurrences. Palaios. 17:134-46
60. Huelsenbeck JP. 1994. Comparing the stratigraphic record to estimates of phylogeny. Paleobiology 20:470-83
61. Hunt G. 2001. Time averaging and morphometric data: Do fossil samples accurately reflect population-level variability? Paleobios 21:69
62. Jablonski D. 1993. The tropics as a source of evolutionary novelty: The post-Palaeozoic fossil record of marine invertebrates. Nature 364:142-44
63. Jablonski D. 1998. Geographic variation in the molluscan recovery from the end-Cretaceous extinction. Science 279:1327-30
64. Jablonski D. 2000. Micro- and Macroevolution: Scale and Hierarchy in Evolutionary Biology and Paleobiology. See Erwin & Wing 2000, p. 15-52
65. Jablonski D, Bottjer DJ. 1991. Environmental patterns in the origins of higher taxa: The post-Paleozoic fossil record. Science 252:1831-33
66. Jablonski D, Lidgard S, Taylor PD. 1997. Comparative ecology of bryozoan radiations: Origin of novelties in cyclostomes and cheilostomes. Palaios 12:505-23
67. Jablonski D, Roy K, Valentine JW, Price RM, Anderson PS. 2002. Pull of the Recent? What pull of the Recent? An analysis of the marine Bivalvia. Abstr. Progr. Geol. Soc. Amer. 34(7): In press
68. Jackson JBC, Cheetham AH. 1994. Phylogeny reconstruction and the tempo of speciation in cheilostome Bryozoa. Paleobiology 20:407-23
69. Jackson JBC, Budd AF, Pandolfi JM. 1996. The shifting balance of natural communities? In Evolutionary Paleobiology, ed. D Jablonski, DH Erwin, JH Lipps, pp. 89-122. Chicago, IL: Univ. Chicago Press
70. Jackson JBC, Cheetham AH. 1999. Tempo and mode of speciation in the sea. Trends Ecol. Evol. 14:72-77
71. Kidwell SM. 1986. Models for fossil concentrations: Paleobiologic implications. Paleobiology 12:6-24
72. Kidwell SM. 1991. The Stratigraphy of Shell Concentrations. See Allison & Briggs 1991, pp. 211-90
73. Kidwell SM. 1993. Taphonomic expressions of sedimentary hiatus: Field observations on bioclastic concentrations and sequence anatomy in low, moderate and high subsidence settings. Geol. Rundsch. 82:189-202
74. Kidwell SM. 2002. Time-averaged molluscan death assemblages: Palimpsests of richness, snapshots of abundance. Geology 30:803-6
75. Kidwell SM, Behrensmeyer AK, eds. 1993. Taphonomic Approaches to Time Resolution in Fossil Assemblages. Knoxville, TN: Paleontol. Soc. Short Courses Paleontol
76. Kidwell SM, Best MMR. 2001. Tropical time-averaging: Disparate scales and taphonomic clocks in bivalve assemblages from modern subtidal siliciclastic and carbonate facies. North Am. Paleontol. Conv. 2001, Program Abstr. PaleoBios 21:79
77. Kidwell S, Bosence DWJ. 1991. Taphonomy and time-averaging of marine shelly faunas. See Allison & Briggs 1991, pp. 115-209
78. Kidwell SM, Brenchley PJ. 1994. Patterns in bioclastic accumulation through the Phanerozoic: Changes in input or in destruction? Geology 22:1139-43
79. Kidwell SM, Flessa KW. 1996. The quality of the fossil record: Populations, species, and communities. Annu. Rev. Earth. Planet. Sci. 24:433-64
80. Kowalewski M. 1996. Taphonomy of a living fossil: The lingulide brachiopod Glottidia palmeri Dall from Baja California, Mexico. Palaios 11:244-65
81. Kowalewski M, Bambach RK. 2002. The limits of paleontological resolution. In High Resolution Approaches in Paleontology, ed. PJ Harries, DH Geary. New York: Kluwer/Plenum. In press
82. Kucera M, Malmgren BA, 1998. Differences between evolution of mean form and evolution of new morphotypes; an example from Late Cretaceous planktonic Foraminifera. Paleobiology 24:49-63
83. Kumar S, Hedges SB. 1998. A molecular timescale for vertebrate evolution. Nature 392:917-20
84. Lieberman BS, Brett CE, Eldredge N. 1995. A study of stasis and change in two species lineages from the Middle Devonian of New York state. Paleobiology 21:15-27
85. Ludvigsen R, Westrop SR, Pratt BR, Tuffnell PA, Young GA. 1986. Dual biostratigraphy: Zones and biofacies. Geosci. Can. 13:139-54
86. MacLeod N. 1991. Punctuated anagenesis and the importance of stratigraphy to paleobiology. Paleobiology 17:167-88
87. MacLeod N, Keller G. 1991. Hiatus distributions and mass extinctions at the Cretaceous/Tertiary boundary. Geology 19:497-501
88. MacLeod N, Ortiz N, Fefferman N, Clyde W, Schulter C, MacLean J. 2000. Phenotypic Response of Foraminifera to Episodes of Global Environmental Change. See Culver & Rawson 2000, pp. 51-78
89. Marshall CR. 1990. Confidence intervals on stratigraphic ranges. Paleobiology 16:1-10
90. Marshall CR. 1995. Stratigraphy, the True Order of Species Originations and Extinctions, and Testing Ancestor-Descendant Hypotheses Among Caribbean Neogene Bryozoans. See Erwin & Anstey 1995, pp. 208-35
91. Marshall CR. 1997. Confidence intervals on stratigraphic ranges with nonrandom distributions of fossil horizons. Paleobiology 23:165-73
92. Marshall CR, Ward PD. 1996. Sudden and gradual molluscan extinctions in the latest Cretaceous of Western European Tethys. Science 274:1360-63
93. Martin RE, Wehmiller JF, Harris MS, Liddell WD. 1996. Comparative taphonomy of foraminifera and bivalves in Holocene shallow-water carbonate and siliciclastic regimes: Taphonomic grades and temporal resolution. Paleobiology 22:80-90
94. McGhee GR Jr, Bayer U, Seilacher A. 1991. Biological and evolutionary responses to transgressive-regressive cycles. In Cycles and Events in Stratigraphy, ed. W Ricken, A Seilacher, pp. 696-708. Berlin: Springer-Verlag
95. McKinney ML. 1986. How biostratigraphic gaps form. J. Geol. 94:875-84
96. McKinney ML. 1991. Completeness of the fossil record: An overview. In The Processes of Fossilization, ed. SK Donovan, pp. 66-83. New York: Columbia Univ. Press
97. Meldahl KH, Flessa KW, Cutler AH. 1997. Time-averaging and postmortem skeletal survival in benthic fossil assemblages: Quantitative comparisons among Holocene environments. Paleobiology 23:209-29
98. Miller AI. 1997. Dissecting global diversity patterns: Examples from the Ordovician Radiation. Annu. Rev. Ecol. Syst. 28:85-104
99. Miller AI. 1998. Biotic transitions in global marine diversity. Science 281:1157-60
100. Miller AI, Cummins H. 1990. A numerical model for the formation of fossil assemblages: Estimating the amount of post- mortem transport along environmental gradient. Palaios 5:303-16
101. Miller AI, Foote M. 1996. Calibrating the Ordovician radiation of marine life: Implications for Phanerozoic diversity trends. Paleobiology 22:304-9
102. Murphy WJ, Eizirik E, O'Brien SJ, Madsen O, Scally M, et al. 2001. Resolution of the early placental mammal radiation using Bayesian phylogenetics. Science 294:2348-51
103. Norris RD. 1991. Biased extinction and evolutionary trends. Paleobiology 17:388-99
104. Olszewski TD. 1999. Taking advantage of time-averaging. Paleobiology 25:226-38
105. Osleger D, Read JF. 1993. Comparative analysis of methods used to define eustatic variations in outcrop: Late Cambrian interbasinal sequence development. Am. J. Sci. 293:157-216
106. Palmer AR. 1965. Biomere - A new kind of biostratigraphic unit. J. Paleontol. 39:149-53
107. Patzkowsky ME, Holland SM. 1997. Patterns of turnover in Middle and Upper Ordovician brachiopods of the eastern United States: A test of coordinated stasis. Paleobiology 23:420-43
108. Patzkowsky ME, Holland SM. 1999. Biofacies replacement in a sequence stratigraphic framework: Middle and Upper Ordovician of the Nashville Dome, Tennessee, USA. Palaios 14:301-23
109. Paul CRC. 1982. The adequacy of the fossil record. In Problems of Phylogenetic Reconstruction, ed. KA Joysey, AE Friday, pp. 75-117. New York: Academic
110. Peters SE, Foote M. 2001. Biodiversity in the Phanerozoic: A reinterpretation. Paleobiology 27:583-601
111. Peterson CH. 1977. The paleoecological significance of undetected short-term temporal variability. J. Paleontol. 51:976-81
112. Powell MG, Kowalewski M. 2002. Increase in evenness and sampled alpha diversity through the Phanerozoic: Comparison of early Paleozoic and Cenozoic marine fossil assumblages. Geology 30:331-34
113. Raup DM. 1979. Biases in the fossil record of species and genera. Bull. Carnegie Mus. Nat. Hist. 13:85-91
114. Raup DM, Sepkoski JJ Jr. 1982. Mass extinctions in the marine fossil record. Science 215:1501-2
115. Rees PM. 2002. Land-plant diversity and the end-Permian mass extinction. Geology 30:827-30
116. Rogers RR, Kidwell SM. 2000. Associations of vertebrate skeletal concentrations and discontinuity surfaces in continental and shallow marine records: A test in the Cretaceous of Montana. J. Geol. 108:131-54
117. Roy K, Valentine JW, Jablonski D, Kidwell S. 1996. Scales of climatic variability and time averaging in Pleistocene biotas: Implications for ecology and evolution. Trends Ecol. Evol. 11:458-63
118. Sadler PM. 1981. Sediment accumulation rates and the completeness of stratigraphic sections. J. Geol. 89:569-84
119. Saltzman MR. 1999. Upper Cambrian carbonate platform evolution, Elvinia and Taenicephalus Zones (Pterocephaliid-Ptychaspid biomere boundary), northwestern Wyoming. J. Sediment. Res. 69:926-38
120. Schopf TJM. 1978. Fossilization potential of an intertidal fauna: Friday Harbor, Washington. Paleobiology 4:261-70
121. Sepkoski JJ Jr. 1984. A kinetic-model of Phanerozoic taxonomic diversity. III. Post-Paleozoic families and mass extinctions. Paleobiology 10:246-67
122. Sepkoski JJ Jr. 1993. Ten years in the library: New data confirm paleontological patterns. Paleobiology 19:43-51
123. Sepkoski JJ Jr. 1997. Biodiversity: Past, present, and future. J. Paleontol. 71:533-39
124. Sepkoski JJ Jr, Bambach RK, Raup DM, Valentine JW. 1981. Phanerozoic marine diversity and the fossil record. Nature 293:435-37
125. Sepkoski JJ Jr, Miller AI. 1985. Evolutionary faunas and the distribution of Paleozoic benthic communities in space and time. In Phanerozoic Diversity Patterns, ed JW Valentine, pp. 153-90. Princeton, NJ: Princeton Univ. Press
126. Sheehan PM, Fastovsky DE, Hoffman RG, Berghaus CB, Gabriel DL. 1991. Sudden extinction of the dinosaurs: Latest Cretaceous, Upper Great Plains, U.S.A. Science 254:835-39
127. Sheldon PR. 1987. Parallel gradualistic evolution of Ordovician trilobites. Nature 330:561-63
128. Signor PW, Lipps JH. 1982. Sampling bias, gradual extinction patterns, and catastrophes in the fossil record. Geol. Soc. Am. Spec. Pap. 190:291-96
129. Smith AB. 2001. Large-scale heterogeneity of the fossil record: Implications for Phanerozoic biodiversity studies. Philos. Trans. R. Soc. London Ser. B 356:351-67
130. Smith AB, Gale AS, Monks NEA. 2001. Sea-level change and rock record bias in the Cretaceous: A problem for extinction and biodiversity studies. Paleobiology 27:241-53
131. Spencer-Cervato C, Thierstein HR, Lazarus DB, Beckmann JP. 1994. How synchronous are Neogene marine plankton events? Paleoceanography 9:739-63
132. Strauss D, Sadler PM. 1989. Classical confidence intervals and the Bayesian probability estimates for the ends of local taxon ranges. Math. Geol. 21:411-27
133. Taylor PD, Allison P. 1999. Bryozoan carbonates through time and space. Geology 26:459-62
134. Valentine JW. 1989. How good was the fossil record? Clues from the Californian Pleistocene. Paleobiology 15:83-94
135. Vrba E. 1985. Environment and evolution: Alternative causes of the temporal distribution of evolutionary events. S. Afr. J. Sci. 81:229-36
136. Wagner PJ, Sidor CA. 2000. Age rank/clade rank metrics - Sampling, taxonomy, and the meaning of "stratigraphic consistency." Syst. Biol. 49:463-79
137. Walker KR, Bambach RK. 1971. The significance of fossil assemblages from fine-grained sediments: Time-averaged communities. Geol. Soc. Am. Abstr. Programs 3:783-84
138. Webb T III. 1993. Constructing the Past from Late Quaternary Pollen Data: Temporal Resolution and a Zoom Lens Space-time Perspective. See Kidwell & Behrensmeyer 1993, pp. 79-101
139. Wignall PB, Hallam A. 1992. Anoxia as a cause of the Permian/Triassic extinction: Facies evidence from northern Italy and the western United States. Palaeogeogr. Palaeoclimatol. Palaeoecol. 93:21-46
140. Wray GA, Levinton JS, Shapiro LH. 1996. Molecular evidence for deep Precambrian divergences among metazoan phyla. Science 274:568-73