701.7  Felony defined and classified.
  A public offense is a felony of a particular class when the statute defining the crime declares it to be a felony. Felonies are class “A” felonies, class “B” felonies, class “C” felonies, and class “D” felonies. Where the statute defining the offense declares it to be a felony but does not state what class of felony it is or provide for a specific penalty, that felony shall be a class “D” felony.
[C51, §2817; R60, §4429; C73, §4104; C97, §5093; C24, 27, 31, 35, 39, §12890; C46, 50, 54, 58, 62, 66, 71, 73, 75, 77, §687.2; C79, 81, §701.7]

See §902.9; see also §724.25