Placozoa – no longer a phylum of one

@article{Voigt2004PlacozoaN,
  title={Placozoa – no longer a phylum of one},
  author={Oliver Voigt and Allen Gilbert Collins and Vicki Buchsbaum Pearse and John S. Pearse and Andrea Ender and Heike Hadrys and Bernd Schierwater},
  journal={Current Biology},
  year={2004},
  volume={14},
  pages={R944-R945}
}

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References

SHOWING 1-10 OF 13 REFERENCES
Placozoa are not derived cnidarians: evidence from molecular morphology.
TLDR
The new molecular morphological characters provide compelling evidence that Trichoplax is not a derived (medusozoan) cnidarian, and it was found that the mitochondrial genome in Cubozoa consists of four linear molecules instead of a single circular molecule or two linear molecules, suggesting that the cubozoans may represent the most derived cNidarian group.
A new perspective on lower metazoan relationships from 18S rDNA sequences.
TLDR
While sequencing additional lineages to identify slowly evolving taxa, the number of complete or nearly complete 18S rDNA sequences for the major diploblastic lineages was increased and the maximum-likelihood framework was used to choose a model which best explains the data.
Phylogeny of Choanozoa, Apusozoa, and Other Protozoa and Early Eukaryote Megaevolution
TLDR
The taxon-rich rRNA phylogeny for eukaryotes allowing for intersite rate variation strongly supports the opisthokont clade and agrees with the view that Choanozoa are sisters of or ancestral to animals and reveals a novel nonflagellate choanozoan lineage, Ministeriida, sister either to choanoflagellates, traditionally considered animal ancestors, or to animals.
Phylogeny of Medusozoa and the evolution of cnidarian life cycles
TLDR
To investigate the evolution of cnidarian life cycles, data from the small subunit of the ribosome are used and indicate that Cnidaria is monophyletic and composed of Anthozoa and Medusozoa.
Growth and Behavior of Trichoplax adhaerens: First Record of the Phylum Placozoa in Hawaii
TLDR
The first record of Trichoplax adhaerens F. Schulze (phylum Placozoa) in Hawaii is reported and some observations on their behavior and growth rates in mixed laboratory culture are described.
Distinct expression patterns of the two T-box homologues Brachyury and Tbx2/3 in the placozoan Trichoplax adhaerens
TLDR
It can be concluded that this simple animal has more than the four cell types described in the literature, and the unresolved position in relation to Porifera, Cnidaria, Ctenophora and Bilateria highlight the necessity of the inclusion of Trichoplax in studies of comparative evolutionary and developmental biology.
Homology of Hox genes and the zootype concept in early metazoan evolution.
TLDR
Comparison of the Trox-2 gene from the presumably most basal metazoan animal, the placozoan Trichoplax adhaerens, to other Hox genes suggests the presence of unambiguous homologs in Hydrozoa and Scyphozoa and the absence of any specific homolog in triploblasts.
The Trox-2 Hox/ParaHox gene of Trichoplax (Placozoa) marks an epithelial boundary
TLDR
The full coding region, spatial expression and function of Trox-2, the single Hox/ParaHox-type gene identified in Trichoplax adhaerens and either a candidate ProtoHox or a ParaHox gene is described.
Evaluating multiple alternative hypotheses for the origin of Bilateria: an analysis of 18S rRNA molecular evidence.
  • A. Collins
  • Biology
    Proceedings of the National Academy of Sciences of the United States of America
  • 1998
TLDR
Six alternative hypotheses for the phylogenetic origin of Bilateria are evaluated by using complete 18S rRNA gene sequences for 52 taxa to suggest that there is little support for three of these hypotheses, but one is most strongly supported.
Global Dispersal of Free-Living Microbial Eukaryote Species
The abundance of individuals in microbial species is so large that dispersal is rarely (if ever) restricted by geographical barriers. This “ubiquitous” dispersal requires an alternative view of the
...
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