Coilopoceras is a compressed, involute, lenticular ammonitid from the Upper Cretaceous with a narrow venter and raggedy ammonitic suture; type of the Coilopceratidae, a family in the Acanthocerataceae

Acanthocerataceae

Acanthocerataceae is a superfamily of extinct Upper Creataceous ammonoid cephalopods belonging to the order, Ammonitida, and comprising some 10 or so families.-Analysis:...

 of the suborder Ammonitina

Ammonitina

The Ammonitina comprises a diverse suborder of ammonoid cephalopods that lived during the Jurassic and Cretaceous periods of the Mesozoic Era. They are excellent index fossils, and it is often possible to link the rock layer in which they are found to specific geological time periods.The shells of...

.

Coilopoceras has an established range from the lower Turonian

Turonian

The Turonian is, in the ICS' geologic timescale, the second age in the Late Cretaceous epoch, or a stage in the Upper Cretaceous series. It spans the time between 93.5 ± 0.8 Ma and 89.3 ± 1 Ma...

 to the Coniacian

Coniacian

The Coniacian is an age or stage in the geologic timescale. It is a subdivision of the Late Cretaceous epoch or Upper Cretaceous series and spans the time between 89.3 ± 1 Ma and 85.8 ± 0.7 Ma...

 in the Upper Cretaceous and may have appeared as low as the upper Cenomanian

Cenomanian

The Cenomanian is, in the ICS' geological timescale the oldest or earliest age of the Late Cretaceous epoch or the lowest stage of the Upper Cretaceous series. An age is a unit of geochronology: it is a unit of time; the stage is a unit in the stratigraphic column deposited during the corresponding...

. Its distribution is widespread, from western North America through northern Africa and Europe to the Middle East.