The lancelets (/ˈlænslɪt, ˈlɑːn-/ LA(H)N-slit), also known as amphioxi (sg.: amphioxus /ˌæmfiˈɒksəs/ AM-fee-OK-səs), consist of 32 described species of somewhat fish-like benthic filter-feeding chordates in the subphylum Cephalochordata, class Leptocardii, and family Branchiostomatidae.
Lancelets diverged from other chordates during or prior to the Cambrian period. A number of fossil chordates have been suggested to be closely related to lancelets, including Pikaia and Cathaymyrus from the Cambrian and Palaeobranchiostoma from the Permian, but their close relationship to lancelets has been doubted by other authors. Molecular clock analysis suggests that modern lancelets probably diversified much more recently, during the Cretaceous or Cenozoic.
