Xenodiscoidea, formerly Xenodiscaceae, is a superfamily within the

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 cuttlefi ...

order

Ceratitida Ceratitida is an order that contains almost all ammonoid cephalopod genera from the Triassic as well as ancestral forms from the Upper Permian The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from t ...

. The superfamily was named by Frech in 1902, presently contains ten families, only one of which was included in the original Otocerataceae of Hyatt, 1900, the remaining having been added. The Xenodiscoidea has its origins in the Middle

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 Pale ...

in the prolecanitid Daraelitidae through the ancestral Xenodiscidae. According to Kummel (1952) and Arkell et al. (1957) the Xenodiscidae gave rise to the Otoceratidae and

Ophiceratidae The Ophiceratidae is a family in the ammonoidea, ammonoid order Ceratitida from the Lower Triassic, previously included in the Otocerataceae but now placed in the Noritiaceae as revised. The Ophiceratidae produced sepenticones with compressed ell ...

. The Ophiceratidae in turn gave rise to the Dieneroceratidae which is considered the source for all remaining ceratitid stocks. All four families made up the original Otocerataceae The Xenodiscidae is removed from the Otocerataceae as originally perceived (Arkell et al. 1957) to become the root of Xenodiscoidea, as emended. The Otoceratidae remains the type family of the Otocerataceae as revised. The Ophiceratidae is reassigned to the Noritaceae along with the Dieneroceratidae. The Huananoceratidae, Liuchengoeratidae, Plueronodoceratidae, and Tapshanitidae, described by Zhao et al. 1978, include Late Permian and Early Triassic genera from Asia. The Xenoceltitidae, established by Spath in 1930 are included in the Treatise in the superfamily Noritaceae The Xenodiscoidea gave rise through the Ophiceratidae to the Noritaceae. and through the Paraceltitidae to the revised Otocerataceae

References

* . * . * . Ceratitida superfamilies Guadalupian first appearances Lopingian extinctions {{Ceratitida-stub