Crustaceomorpha is a proposed clade of arthropods that includes crustaceans and numerous extinct groups. Synapomorphies for the clade are that the larval antenna is a feeding or locomotory organ, and there are six endopodal podomeres in post-antennal limbs.[1]
Extinct groups included in Crustaceomorpha vary considerably. It includes Agnostida (usually treated under Trilobita), Waptiida, Isoxyida, Phosphatocopida, and Bradoriida, among others. These primitive crustaceomorphs are grouped under Pseudocrustacea.[2]
The validity of Crustaceomorpha is controversial. It has more support among paleontologists who consider it a sister group to Arachnomorpha, which includes trilobites and chelicerates (see cladogram below). Both are grouped under Schizoramia, a clade of arthropods with biramous appendages.[3] In contrast, neontologists tend to support the Mandibulata clade, which groups members of Crustacea together with Hexapoda and Myriapoda.[4]