Fossils of inoceramids are found in marine sediments of Permian to latest Cretaceous in age.

[1] Many species of inoceramid are found all over the world, demonstrating the wide distribution of their preferred ecosystems, and possibly long-lived planktotrophic larvae.

[2] Despite their wide distribution, the pace of evolution of inoceramids was great, with species ranges commonly averaging 0.2-0.5 Ma.

Members of the Inoceramus and Cladoceramus genera have shells of more than 1 metre (3 ft 3 in) in length.

[2] In 1952, a huge specimen of Inoceramus steenstrupi 1.87 metres (6 ft 2 in) long, was found in Qilakitsoq, the Nuussuaq Peninsula, Greenland.