Fossil specimen of the nautiloid cephalopod *Eutrephoceras dekayi* from the Cretaceous Pierre Shale of the Black Hills of South Dakota (PRI 44557). Specimen is from the collections of the [Paleontological Research Institution](http://www.priweb.org), Ithaca, New York. Maximum diameter of specimen is approximately 6 cm. Model by Emily Hauf.