Wikipedia
Eowellerites
Eowellerites is genus of ammonoid cephalopod belonging to the Welleritidae family. Species belonging to this genus lived in middle Pennsylvanian ( Moscovian). Its fossils were found in USA and Japan. It had thinly discoidal shells with a quite wide umbilicus (U/D = 0.3 - 0.5). While in juvenile stages (up to 15 mm in diameter) venter is moderately rounded, it becomes slightly rounded to flattened when becoming mature (100 mm in diameter). 12-lobed suture has adventitious lobe on the first lateral saddle and is also characterized by an addition of an umbilical lobe. Sutural formula is (V V) L L (U U): I D. It has evolved from Winslowoceras henbesti and gave rise to genus Wellerites.