The genus has been found from many continents and is thought to have had a large global distribution during the Maastrichtian stage of the Late Cretaceous.

[6] There is also evidence of the genus being present from the island of Trinidad, although the material found from here cannot be classified at the species level.

[7] Common species found in North America include S. lobatus, S. lenticularis, and S. pleurisepta.

The shell of Sphenodiscus was streamlined and lateromedially compressed with overlapping whorls and a small umbilicus.

[11] Sphenodiscus had a complex suture pattern with many small branching lobes and saddles.