Trigonoceratidae

The Trigonoceratidae is a family of trigonoceratacean nautiloids that lived from the Early Carboniferous (Mississippian) to the Early Permian, characterized by loosely coiled to evolute shells with oval to quadrate, depressed to compressed, whorl sections generally bearing longitudinal ridges.

Genera within the Trigonoceratidae include Trigonoceras, Aphelaeceras, Chouteauoceras, Discitoceras, Epistroboceras, and Maccoyoceras.

The Trigonoceratidae is thought to have its origin in the Centroceratidae in the Mississippian, and does not seem to have been the source for any other group.