Arpaditidae

The Arpaditidae comprise a family of generally compressed evolute ceratitid ammonoids from the middle and upper Triassic with a median furrow along the outer rim of the shell,(venter), typically bordered by smooth or crenulated keels. Sides have sigmoidal ribs and tubercles. Sutures are ceratitic or ammonitic.

The Arpaditidae are now included in the Trachycerataceae, according to E. T. Tozer 1980, having been removed from the Clydonitaceae.