The age and relationships of the major animal phyla

Research output: Contribution to journalArticlepeer-review

46 Scopus citations


Given the uncertainties in the fossil record and the paucity of informative morphological characters, there is still considerable uncertainty as to the phylogenetic affinities and times of origins of essentially all of the phyla of animals. A multilocus analysis of amino-acid sequence data for mitochondrial genes suggests that the major triploblast phyla began diverging approximately 630 million years ago. These results support the hypothesis that the so-called Cambrian radiation of animals actually initiated about 100 million years prior to the Cambrian, as the fossil evidence suggests. In addition, phylogenetic analysis supports the monophyly of animals, an early (~900 million years ago) branching off of the cnidarian lineage, the monophyly of deuterostomes and protostomes, and the inclusion of nematodes in the protostome lineage. The results of this study suggest that, with appropriate levels of taxon sampling and a focus on conserved regions of protein-coding sequence, complete mitochondrial genome analysis may be sufficiently powerful to elucidate the genealogical relationships of many of the animal phyla.

Original languageEnglish (US)
Pages (from-to)319-325
Number of pages7
Issue number2
StatePublished - Apr 1999
Externally publishedYes


  • Animal phyla
  • Annelida
  • Arthropoda
  • Cambrian radiation
  • Cnidaria
  • Invertebrate phylogeny
  • Mollusca

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Genetics
  • General Agricultural and Biological Sciences


Dive into the research topics of 'The age and relationships of the major animal phyla'. Together they form a unique fingerprint.

Cite this