What is "planitornoceras"

Planitornoceras is a genus included in the geniatitid subfamily Aulatornoceratinae that lived during the Famennian stage at the end of the Devonian. Its shell is extremely compressed, subinvolute to subevolute with an open umbilucus. Sides are always flat, outer rim (=venter) tabulate to slightly keeled. No constrictions or spiral grooves, but some species have broad spiral depressions. The adventitious lobe of the suture is widely rounded and asymmetric, the ventral lobe and saddle small, the dorsolateral saddle relatively short.