The ancient -LRB- cohort Belemnoidea -RRB- and modern -LRB- cohort Neocoleoidea -RRB- coleoids , as well as the ammonoids , all diverged from the external shelled nautiloid during the middle MISC@1 , between NUMBER@1 and NUMBER@2 million years ago , although the coleoids may be polyphyletic .

The ancient -LRB- cohort Belemnoidea -RRB- and modern -LRB- cohort Neocoleoidea -RRB- coleoids , as well as the ammonoids , all diverged from the external shelled nautiloid during the middle MISC@1 , between NUMBER@1 and NUMBER@2 million years ago .
