Thalassoceratidae a family of late Paleozoic

ammonites Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttlefish) ...

included in the goniatitid superfamily

Thalassoceratoidea Thalassoceratoidea, formerly Thalassocerataceae, is a superfamily of Late Paleozoic ammonites characterized by their thick-discoidal to subglobular, involute shells with narrow or closed umbilici and biconvex growth striae with ventral sinuses. ...

along with the Bisatoceratidae. Some eight genera are included, although the specific number and exactly which depends on the particular classification. Thalassoceratids are characterized by thick-discoidal to subglobular, involute shells with narrow or closed umbilici and serrate or digitate external lobes in the suture. This latter distinguishes them from the Bisatoceratidae in which the external lobes are smooth. The ventral lobe is extremely wide; the height of median saddle may exceed half the height of the entire ventral lobe itself. Some forms have ventrolateral grooves but spiral ornamentation is absent. Miller, Funish, and Schindewolf, 1957, in the

Treatise on Invertebrate Paleontology The ''Treatise on Invertebrate Paleontology'' (or ''TIP'') published by the Geological Society of America and the University of Kansas Press, is a definitive multi-authored work of some 50 volumes, written by more than 300 paleontologists, and co ...

Part L included ''Thalassoceras'', ''Eothalassoceras'', ''Delepinoceas'', ''Gleboceras'', ''Epithalassoceras''. Saunders, Work, and Nikolaeva, 1999, included ''Eothalassoceras'', ''Prothalassoceras'', ''Gleboceras'', ''Aistoceras'', ''Thalassoceras'', ''Epithalassoceras'', ''Aristoceratoides''. In the revised Treatise (W.M. Furnish et al. 2009) the Thalassoceratidae is divided into two subfamilies, the Gleboceratinae which includes ''Gleboceras'' and ''Mapesites'' and the Thalssoceratinae which includes ''Aristoceras'', ''Aristoceratoides'', ''Eothalassoceras'', ''Epithalassoceras'', ''Prothalassoceras'', and ''Thalassoceras''. Leonova & Boiko (2011) later removed ''Mapesites'' from Thalassoceratidae due to its ornamentation being vastly different from ''Gleboceras''. They also utilized the subfamily Aristoceratinae, which involved an evolutionary sequence from ''Aristoceras'' to ''Allothalassoceras'' to ''Aristoceratoides.''

References

Thalassoceratidae in GONIAT Online
6/14/12 * W. B. Saunders, et al., 1999. Evolution of Complexity in Paleozoic Ammonoid Sutures, Supplementary Material. Science Magazin

* * Goniatitida families Thalassoceratoidea {{Goniatitida-stub