Kant, R. Studies of allometric growth in paleozoic ammonoids with special reference
to individual "populations". 1973.

 Summary: The allometric relationships existing between whorl width (Wb) and
  shell or umbilical radius (Rd or rd, resp.) are analysed and, with regard to the
  'behaviour' of the individual parameters, evaluated.  The results permit the
  recognition of phenotypes.  With the help of allometric relationships taxonomic
  questions can be settled in some groups.  A comparison with Nautilus with respect
  to the Bautechnik and a possible sexual dimorphism is given.