cenogenesis kenogenesis caenogenesis cainogenesis kainogenesis
cenogenesis%1:22:00:: kenogenesis%1:22:00:: caenogenesis%1:22:00:: cainogenesis%1:22:00:: kainogenesis%1:22:00::
introduction during embryonic development of characters or structure not present in the earlier evolutionary history of the strain or species (such as the addition of the placenta in mammalian evolution)