Eumetazoa (), also known as Epitheliozoa or Histozoa, is a proposed basal animal subkingdom as a sister group of Porifera (sponges). The basal eumetazoan clades are the Ctenophora and the ParaHoxozoa. Placozoa is now also seen as a eumetazoan in the ParaHoxozoa. The competing hypothesis is the Myriazoa clade. The subkingdom Parazoa and Agnotozoa are the other taxa, and agnotozoa may be fake or even nonexistent at studies. Parazoa or Agnotozoa are a main sister group to eumetazoans, forming clade Blastozoa/Diploblastozoa. Alternatively, Parazoa was considered as a sister group to Agnotozoa(now considered polyphyletic). Several other extinct or obscure life forms, such as Iotuba and Thectardis, appear to have emerged in the group. Characteristics of eumetazoans include true tissues organized into , the presence of neurons and muscle tissue, and an embryo that goes through a gastrula stage.
Some phylogenetics once speculated the sponges and eumetazoans Evolution separately from different single-celled organisms, which would have meant that the animal kingdom does not form a clade (a complete grouping of all organisms descended from a common ancestor). However, genetic studies and some morphological characteristics, like the common presence of , now unanimously support a common origin.
Traditionally, eumetazoans are a major group of in the Five Kingdoms classification of Lynn Margulis and K. V. Schwartz, comprising the Radiata and Bilateria – all animals except the sea sponge. "Systema Naturae 2000 Taxon: Subkingdom Eumetazoa". . Retrieved February 2, 2006
However, some skeptics emphasize inconsistencies in the new data. The zoologist Claus Nielsen argues in his 2001 book Animal Evolution: Interrelationships of the Living Phyla for the traditional divisions of protostome and deuterostome.
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