Search tips
Search criteria 


Logo of procbThe Royal Society PublishingProceedings BAboutBrowse by SubjectAlertsFree Trial
Proc Biol Sci. 1999 January 22; 266(1415): 163–171.
PMCID: PMC1689654

Divergence time estimates for the early history of animal phyla and the origin of plants, animals and fungi.


In the past, molecular clocks have been used to estimate divergence times among animal phyla, but those time estimates have varied widely (1200-670 million years ago, Ma). In order to obtain time estimates that are more robust, we have analysed a larger number of genes for divergences among three well-represented animal phyla, and among plants, animals and fungi. The time estimate for the chordate-arthropod divergence, using 50 genes, is 993 +/- 46 Ma. Nematodes were found to have diverged from the lineage leading to arthropods and chordates at 1177 +/- 79 Ma. Phylogenetic analyses also show that a basal position of nematodes has strong support (p > 99%) and is not the result of rate biases. The three-way split (relationships unresolved) of plants, animals and fungi was estimated at 1576 +/- 88 Ma. By inference, the basal animal phyla (Porifera, Cnidaria, Ctenophora) diverged between about 1200-1500 Ma. This suggests that at least six animal phyla originated deep in the Precambrian, more than 400 million years earlier than their first appearance in the fossil record.

Full Text

The Full Text of this article is available as a PDF (140K).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.
  • Aguinaldo AM, Turbeville JM, Linford LS, Rivera MC, Garey JR, Raff RA, Lake JA. Evidence for a clade of nematodes, arthropods and other moulting animals. Nature. 1997 May 29;387(6632):489–493. [PubMed]
  • Archibald JD. Fossil Evidence for a Late Cretaceous Origin of "Hoofed" Mammals. Science. 1996 May 24;272(5265):1150–1153. [PubMed]
  • Ayala FJ, Rzhetsky A, Ayala FJ. Origin of the metazoan phyla: molecular clocks confirm paleontological estimates. Proc Natl Acad Sci U S A. 1998 Jan 20;95(2):606–611. [PubMed]
  • Brown RH, Richardson M, Boulter D, Ramshaw JA, Jefferies RP. The amino acid sequence of cytochrome c from Helix aspersa Müller (garden snail). Biochem J. 1972 Jul;128(4):971–974. [PubMed]
  • Canfield DE, Teske A. Late Proterozoic rise in atmospheric oxygen concentration inferred from phylogenetic and sulphur-isotope studies. Nature. 1996 Jul 11;382(6587):127–132. [PubMed]
  • Davidson EH, Peterson KJ, Cameron RA. Origin of bilaterian body plans: evolution of developmental regulatory mechanisms. Science. 1995 Nov 24;270(5240):1319–1325. [PubMed]
  • Gu X. The age of the common ancestor of eukaryotes and prokaryotes: statistical inferences. Mol Biol Evol. 1997 Aug;14(8):861–866. [PubMed]
  • Gu X. Early metazoan divergence was about 830 million years ago. J Mol Evol. 1998 Sep;47(3):369–371. [PubMed]
  • Gu X, Zhang J. A simple method for estimating the parameter of substitution rate variation among sites. Mol Biol Evol. 1997 Nov;14(11):1106–1113. [PubMed]
  • Hedges SB, Parker PH, Sibley CG, Kumar S. Continental breakup and the ordinal diversification of birds and mammals. Nature. 1996 May 16;381(6579):226–229. [PubMed]
  • Higgins DG, Bleasby AJ, Fuchs R. CLUSTAL V: improved software for multiple sequence alignment. Comput Appl Biosci. 1992 Apr;8(2):189–191. [PubMed]
  • Knoll AH. The early evolution of eukaryotes: a geological perspective. Science. 1992 May 1;256(5057):622–627. [PubMed]
  • Kuma K, Nikoh N, Iwabe N, Miyata T. Phylogenetic position of Dictyostelium inferred from multiple protein data sets. J Mol Evol. 1995 Aug;41(2):238–246. [PubMed]
  • Kumar S, Hedges SB. A molecular timescale for vertebrate evolution. Nature. 1998 Apr 30;392(6679):917–920. [PubMed]
  • Kumar S, Rzhetsky A. Evolutionary relationships of eukaryotic kingdoms. J Mol Evol. 1996 Feb;42(2):183–193. [PubMed]
  • Li CW, Chen JY, Hua TE. Precambrian sponges with cellular structures . Science. 1998 Feb 6;279(5352):879–882. [PubMed]
  • Nikoh N, Iwabe N, Kuma K, Ohno M, Sugiyama T, Watanabe Y, Yasui K, Shi-cui Z, Hori K, Shimura Y, et al. An estimate of divergence time of Parazoa and Eumetazoa and that of Cephalochordata and Vertebrata by aldolase and triose phosphate isomerase clocks. J Mol Evol. 1997 Jul;45(1):97–106. [PubMed]
  • Ohno S. The notion of the Cambrian pananimalia genome. Proc Natl Acad Sci U S A. 1996 Aug 6;93(16):8475–8478. [PubMed]
  • Rzhetsky A, Kumar S, Nei M. Four-cluster analysis: a simple method to test phylogenetic hypotheses. Mol Biol Evol. 1995 Jan;12(1):163–167. [PubMed]
  • Seilacher A, Bose PK, Pfluger F. Triploblastic animals more than 1 billion years ago: trace fossil evidence from india . Science. 1998 Oct 2;282(5386):80–83. [PubMed]
  • Takezaki N, Rzhetsky A, Nei M. Phylogenetic test of the molecular clock and linearized trees. Mol Biol Evol. 1995 Sep;12(5):823–833. [PubMed]
  • Vanfleteren JR, Van de Peer Y, Blaxter ML, Tweedie SA, Trotman C, Lu L, Van Hauwaert ML, Moens L. Molecular genealogy of some nematode taxa as based on cytochrome c and globin amino acid sequences. Mol Phylogenet Evol. 1994 Jun;3(2):92–101. [PubMed]
  • Wainright PO, Hinkle G, Sogin ML, Stickel SK. Monophyletic origins of the metazoa: an evolutionary link with fungi. Science. 1993 Apr 16;260(5106):340–342. [PubMed]

Articles from Proceedings of the Royal Society B: Biological Sciences are provided here courtesy of The Royal Society