Cyrtonellida
Encyclopedia
Cyrtonellida is a group of "monoplacophora
", representing either a sister taxon
to, or a polyphyletic assemblage including, the Trybliida.
Monoplacophora
Monoplacophora, meaning "bearing one plate", is a polyphyletic class of mollusks with a cap-like shell, living on the bottom of deep sea. Extant representatives were unknown until 1952; previously they were known only from the fossil record.- Definition :...
", representing either a sister taxon
Taxon
|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...
to, or a polyphyletic assemblage including, the Trybliida.