Nephrozoa

Nephrozoa is a proposed major clade of bilaterian animals. It includes all bilaterians other than Xenacoelomorpha. It contrasts with the Xenambulacraria hypothesis, which instead posits that Xenacoelomorpha is most closely related to Ambulacraria. Which hypothesis is correct is controversial. Authors supporting the Xenambulacraria hypothesis have suggested that the genetic evidence used to support Nephrozoa may be due to systematic error.

Below is a proposed phylogenetic tree of Nephrozoa: