The ammonoid fauna from the Late Devonian Three Forks of Montana is revised.  Six taxa were recognised, which
   belong to the genera Tornoceras, Pernoceras, Raymondiceras, Platyclymenia, Pleuroclymenia, and Carinoclymenia.
   The ammonoid assemblage suggests a stratigraphic position within the middle Famennian, most probably the
   Platyclymenia annulata Zone. The ammonoids display extreme septal crowding in intermediate as well as adult
   growth stages, which can be regarded as evidence for instable palaeoecological conditions during lifetime of the
  animals.