''Xenodiscus'' is an extinct

ammonoid 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) ...

cephalopod A cephalopod is any member of the molluscan class Cephalopoda (Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head ...

genus and one of the earliest

ceratites ''Ceratites'' is an extinct genus of ammonite cephalopods. These nektonic carnivores lived in marine habitats in what is now Europe, during the Triassic, from the upper-most Anisian to the lower Ladinian age.Sepkoski, JacSepkoski's Online Genus D ...

, found in the Upper

Permian The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleoz ...

of northern India and Timor. ''Xenodiscus'' is included in the family Xenodiscidae which is part of the ceratite superfamily Xenodiscaceae ''Xenodiscus'' has a thinly discoidal and ribbed shell with ceratitic sutures, coiled so all whorls are exposed. The whorl section is subquadrate and compressed, so as to be narrower than high.

References

* Arkell et al., 1957; Suborder Ceratitina in the Treatise on Invertebrate Paleontology Part L Ammonoidea; Geological Soc. of America and Univ Kansas press. Ceratitida genera Xenodiscidae Ammonites of Asia Permian ammonites {{Ceratitida-stub