Wherever any municipality pursuant to an act of the legislature of this state shall have adopted an ordinance or ordinances for any of the purposes covered by sections 89.010 to 89.140, such ordinance or ordinances shall be deemed to have been adopted under the provisions of sections 89.010 to 89.140, and it shall not be necessary in such cases for the local legislative body to appoint a zoning commission as provided in section 89.070. All such ordinances shall remain in full force and effect, except so far as they shall be inconsistent with the provisions of sections 89.010 to 89.140, until they shall have been amended, altered or repealed by such legislative body.