Fig. 4From: 3-D orientation and distribution of ammonites in a concretion from the Upper Cretaceous Pierre Shale of Montana a Dip angle of the ammonites in the sculpture (0° = horizontal, 90° = vertical). b Dip direction of the ammonites in the sculpture (0° = north). Most of the ammonites dip preferentially toward the east. c Plot of the lowest points of the ammonites in the sculpture with respect to their height and length along the bottomBack to article page