Le problème de l'origine de la métamérie des vertébrés et la crise de la morphologie transformiste

“A fish-like thing appeared among the Annelids one day.It hadn’t any parapods or setae to display.It hadn’t any eyes or jaws or central nervous cordBut it had a lot of gill slits and it had a notochord ! Chorus :It’s a long way from AmphioxusIt’s a long way to us.It’s a long way from AmphioxusTo the meanest human cuss.It’s good-bye fins and gill slits,Wellcome skin and hair.It’s a long way from AmphioxusBut we came from there. [...] My notochord shall grow into a chain of vertebraeAs fins my ...