Xenoceltites is an extinct ceratite

Ceratitida

The Ceratitida is an order that contains almost all ammonoid cephalopod genera from the Triassic as well as ancestral forms from the Upper Permian, the exception being the phylloceratids which gave rise to the great diversity of post Triassic ammonites....

 ammonite found world wide in the Lower Triassic

Triassic

The Triassic is a geologic period and system that extends from about 250 to 200 Mya . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events...

. Xenoceltites belongs to the Xenoceltitidae, a taxonomic family within the ceratites that with two others now form the superfamily Xenodiscaceae. One of the earliest ceratites, Xenoceltities has a narrow planospiral shell with a compressed whorl section, that has a suture with 2 weakly toothed lateral lobes and irregular ribbing .