''Ussuria'' is a genus of Lower Triassic

ammonite 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) ...

s with a smooth, involute discoidal shell with submonophyllic sutures, belonging to the ceratitid family

Ussuriidae Ussuriidae is an extinct family of cephalopods belonging to the Ammonite order Ceratitida and superfamily Noritoidea Noritoidea, formerly Noritaceae, is an extinct superfamily of cephalopods belonging to the Ammonite order Ceratitida. Nori ...

. ''Ussuria'' has been found in Russia in

Siberia Siberia ( ; rus, Сибирь, r=Sibir', p=sʲɪˈbʲirʲ, a=Ru-Сибирь.ogg) is an extensive geographical region, constituting all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has been a part of ...

(original discovery),

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

Oman Oman ( ; ar, عُمَان ' ), officially the Sultanate of Oman ( ar, سلْطنةُ عُمان ), is an Arabian country located in southwestern Asia. It is situated on the southeastern coast of the Arabian Peninsula, and spans the mouth of t ...

, and

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in the United States.

Description

The shell of ''Ussuria'' is laterally compressed and involute. Whorls are deeply embracing, increasing rapidly in height. Umbilicus is narrow and deep with rounded shoulders. Sides gently convex, converging on a narrow rounded venter. Sutures are ammonitic, with digitate lobes and submonophyllic saddles. The external,(or ventral), lobe is divided by a broad digitate siphonal saddle with each side of the lobe deeply trifid. The two or three principal lateral lobes on either side that are wide and deeply digitate, followed dorsally by another three or more smaller, also digitate, auxiliary lobes. The first lateral saddle is typically indented only on the ventral (rim) side and the second lateral saddle only of the dorsal side. ''Ussuria'' somewhat resembles '' Sturia'', commonly placed in the Ptychitidae. The early growth stages of ''Ussuria'' are like '' Dimorphoceras'', the intermediate growth stage like '' Thalassoceras''.

Taxonomy

Hyatt Hyatt Hotels Corporation, commonly known as Hyatt Hotels & Resorts, is an American multinational hospitality company headquartered in the Riverside Plaza area of Chicago that manages and franchises luxury and business hotels, resorts, and vacat ...

classified ''Ussuria'' in the Ussuriidae, based on Siberian forms, which is followed by W.J. Akell, et al., in the American Treatise part L, 1957. Related genera include '' Metussuria'', '' Oxyussuria'', and '' Parussuria''. Other classifications place Ussuriidae, including ''Ussuria'', in the Meekocerataceae, an alternative for the Noritaceae.

References

*W.J. Arkell et al.,1957. Mesozoic Ammonoidea. Treatise on Invertebrate Paleontology, Part L. Geological Soc of America. Geological Society of America and University of Kansas Press. *

James Perrin Smith James Perrin Smith (November 27, 1864 – January 1, 1931) was an American geologist and paleontologist. Smith was of English descent. T. M. Forster, one of his ancestors, was a surgeon in the Royal Navy and moved to Virginia in 1745. His paternal ...

, 1932. Lower Triassic Ammonoids of North America, US Geological Survey, Professional Paper 167.
Paleobiology Database-Ussuria
Noritoidea Triassic ammonites Ceratitida genera Triassic animals of Asia {{Ceratitida-stub