Platyzoa
{{Taxobox
color = pink | name = Platyzoa | image = Bedford's Flatworm.jpg | image_width = 200px | image_caption = Bedford's Flatworm (Pseudobiceros bedfordi), a Platyhelminth, or flatworm | regnum = Animalia | subregnum = Eumetazoa | unranked_phylum = Bilateria | superphylum = Platyzoa | superphylum_authority = Cavalier-Smith, 1998 | subdivision_ranks = Phyla | subdivision =
* Platyhelminthes
* Gastrotricha
*Gnathifera
** Rotifera
** Acanthocephala
** Gnathostomulida
** Micrognathozoa
** CycliophoraThe Platyzoa are a group of protostome animals proposed by Thomas Cavalier-Smith in 1998. Cavalier-Smith included in Platyzoa the Phylum Platyhelminthes or flatworms, and a new phylum, Acanthognatha, into which he gathered several previously described phyla of microscopic animals. Subsequent studies have supported Platyzoa as a clade, a monophyletic group of organisms with a common ancestor, while differing on the phyla included and on relationships within Platyzoa.
One current scheme places the following traditional phyla in Platyzoa:
* Platyhelminthes
* Gastrotricha
* Gnathifera
** Rotifera
** Acanthocephala
** Gnathostomulida
** Micrognathozoa
** Cycliophora
The Platyhelminthes and Gastrotricha are acoelomate. The other phyla have a pseudocoel, and share characteristics such as the structure of their jaws and pharynx, although these have been secondarily lost in the parasitic Acanthocephala. They form a monophyletic subgroup called the Gnathifera.
The Platyzoa are close relatives of the Lophotrochozoa, and are sometimes included in that group. Together the two make up the Spiralia.*The Taxonomicon - Taxon: Infrakingdom Platyzoa Cavalier-Smith, 1998 - retrieved January 31 2006
*The interrelationships of metazoan parasites: a review of phylum- and higher-level hypotheses from recent morphological and molecular phylogenetic analyses - retrieved January 31 2006
*Triploblastic Relationships with Emphasis on the Acoelomates and the Position of Gnathostomulida, Cycliophora, Plathelminthes, and Chaetognatha: A Combined Approach of 18S rDNA Sequences and Morphology - retrieved January 31 2006
*Myzostomida Are Not Annelids: Molecular and Morphological Support for a Clade of Animals with Anterior Sperm Flagella - retrieved January 31 2006
*Current advances in the phylogenetic reconstruction of metazoan evolution. A new paradigm for the Cambrian explosion? - retrieved January 31 2006
|
