Pen Formation
The Pen Formation is a Campanian-age geologic unit in the western United States.
Vertebrate fauna
Sharks are well known from the Pen Formation.- Lonchidion selachos
- Squalicorax kaupi
- Cretorectolobus olsoni
- Ischyrhiza mira
- Scapanorhynchus texanus
- S. raphiodon
- Cretolamna appendiculata