Romerodus sp.
Shark
Middle Pennsylvanian (Missourian)
Hushpuckney Shale Member, Swope Formation
Hansen Quarry,Nebraska, USA

Counterpart.  Extremely rare eugeneodontid shark.

This is one of those Paleozoic chondrichthyans that belonged to an extinct group only distantly related to the lineages that led to Mesozoic and Cenozoic sharks.  It was more closely-related to the bizarre Edestus and Helicoprion than to modern forms.