''Ussurites'' 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 genus belonging to the suborder

Phylloceratina The Phyllocertina comprise a suborder of ammonoid cephalopods, belonging to the Ammonitida, whose range extends from the Lower Triassic to the Upper Cretaceous. Shells of the Phylloceratina are generally smooth with small to large umbilici and ...

and is included in the family

Ussuritidae Ussuritidae are ancestral, Triassic, Phylloceratina characterized by generally smooth, discoidal, evolute shells with rounded venters and little or no ornamentation and by sutures with primitive monophyllitic saddles with a single terminal branch ...

. Its range is restricted to the early Middle Triassic, (

Anisian In the geologic timescale, the Anisian is the lower stage or earliest age of the Middle Triassic series or epoch and lasted from million years ago until million years ago. The Anisian Age succeeds the Olenekian Age (part of the Lower Triassic Ep ...

) As with the family, the shell of ''Ussurites'' is discoidal, evolute, and generally smooth. The suture is phylletic with divided lobes and simple, rounded, elongate saddles. The ventral lobe is bifurcated, the two branches sharply serrated. The two lateral lobes are asymmetrically trifurcated, sections sharply pointed. The first lateral saddle (closest to the venter) is fairly evenly rounded, the second and third are narrower and asymmetric, leaning away from the venter and toward the umbilicus. ''

Monophyllites ''Monophyllites'' is an extinct cephalopod genus belonging to the family Ussuritidae that lived during the Triassic period, from Anisian to Ladinian age. Description "Form evolute laterally compressed. Whorl low and increasing slowly in height, ...

'', which extends through the Middle Triassic into the

Carnian The Carnian (less commonly, Karnian) is the lowermost stage of the Upper Triassic Series (or earliest age of the Late Triassic Epoch). It lasted from 237 to 227 million years ago (Ma). The Carnian is preceded by the Ladinian and is followed by t ...

is similar, differing in the details of the suture.

References

* Arkell ''et al.'', 1957. Mesozoic Ammonoides; Treatise on Invertebrate Paleontology, Part L (Ammonoidea). Geol Soc of America and Univ Kansas Press. p. L185-186. Triassic ammonites Ammonitida Fossils of Svalbard Anisian life {{Svalbard-stub