Thalassoceratidae a family of late Paleozoic ammonites included in the goniatitid superfamily Thalassoceratoidea along with the Bisatoceratidae.

Thalassoceratids are characterized by thick-discoidal to subglobular, involute shells with narrow or closed umbilici and serrate or digitate external lobes in the suture.

Miller, Funish, and Schindewolf, 1957, in the Treatise on Invertebrate Paleontology Part L included Thalassoceras, Eothalassoceras, Delepinoceas, Gleboceras, Epithalassoceras.

Saunders, Work, and Nikolaeva, 1999, included Eothalassoceras, Prothalassoceras, Gleboceras, Aistoceras, Thalassoceras, Epithalassoceras, Aristoceratoides.

Leonova & Boiko (2011) later removed Mapesites from Thalassoceratidae due to its ornamentation being vastly different from Gleboceras.