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

Other fishes include Xiphactinus, the ray Ptychotrygon, and gar. The nodosaurid ankylosaurs Acantholipan and CPC 273 have also been found in the Pen Formation.