''Nautilus cookanum'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

species of nautilus. It lived during the

Eocene The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...

epoch In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured. The moment of epoch is usually decided by ...

. ''N. cookanum'' placed within the genus ''Nautilus'', together with extant species based on their shared shell characters.Ward, P.D. & W.B. Saunders 1997
''Allonautilus'': a new genus of living nautiloid cephalopod and its bearing on phylogeny of the Nautilida
''Journal of Paleontology'' 71(6): 1054–1064. Fossils of the species from the

Late Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', "daw ...

Hoko River Formation The Hoko River Formation is a Late Eocene marine sedimentary geologic formation. The formation is exposed in outcrops along the Strait of Juan de Fuca on the Olympic Peninsula in Washington state, USA. It is known for containing numerous fossils ...

are noted as one of the two oldest occurrences for the genus (with the other, older occurrence being '' N. praepompilius'' of the

Paleogene The Paleogene ( ; British English, also spelled Palaeogene or Palæogene; informally Lower Tertiary or Early Tertiary) is a geologic period, geologic period and system that spans 43 million years from the end of the Cretaceous Period million yea ...

References

Prehistoric nautiloids Nautiluses Eocene molluscs Eocene animals of North America Fossil taxa described in 1892 {{paleo-Nautiloidea-stub