Connecting rings are thick and layered, externally straight but thickening inwardly with the maximum near the middle of the segment so as to leave concave depressions on internal siphuncle molds.

Septal necks are typically orthochoanitic but vary in length from almost absent (achoanitic) to reaching halfway to the previous septum (hemichoanitic) and may even slope inwardly (loxochoanitic).

[2][3] The earliest described, assigned to the Ellesmeroceratidae, is the early Trempealeauan Hunuanoceras, which comes from the lower part of the upper Yenchou Member of the Fengshan Formation in China.

The Ellesmeroceratidae gave rise within the Ellesmerocerida to the Protocycloceratidae, Bassleroceratidae, and possibly the Cylostomiceratidae in the early Canadian (late Gasconadian (?

The Ellesmeroceratidae also gave rise at about the close of the Gasconadian to the Endocerida, Tarphycerida, and to the Orthocerida through the ancestral Baltoceratidae,[4][5][6][7] at which time they cease to be the dominant element in cephalopod faunas.