''Jiagouceras'' is a genus of early primitive

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 ...

s from the

Upper Cambrian The Furongian is the fourth and final epoch and series of the Cambrian. It lasted from to million years ago. It succeeds the Miaolingian series of the Cambrian and precedes the Lower Ordovician Tremadocian Stage. It is subdivided into three ...

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 ...

, assigned to the

Plectronoceratidae Plectronocerida is a primitive order from which subsequent cephalopod orders are ultimately derived.Curt Teichert, 1988. Main Features of Cephalopod Evolution. The Mollusca Vol. 12 Paleontology and Neontology of Cephalopds; Academic Pres Inc. Oc ...

. The shell is small, nearly straight with a slight endogastric curvature and compressed cross section. The

siphuncle The siphuncle is a strand of tissue passing longitudinally through the shell of a cephalopod mollusk. Only cephalopods with chambered shells have siphuncles, such as the extinct ammonites and belemnites, and the living nautiluses, cuttlefish, and ...

is close to the ventral margin, with segments expanded into the chambers. ''Jiagouceras'' is found in the Wanwankou member of the

Fengshan formation Fengshan may refer to: *Feng Shan, Chinese religious ritual Geographic names People's Republic of China *Fengshan County, Guangxi () ;Subdistricts () *Fengshan Subdistrict, Shanwei, in Cheng District, Shanwei, Guangdong *Fengshan Subdistrict ...

(Early, Middle and Upper

Trempealeauan The Trempealeauan is the upper or latest stage of the Upper or Late Cambrian in North America, spanning about 4 million years from about 492.5 to 488.3 m.y.a., equivalent to the Fengshanian of China. The name comes from the Trempealeau Formation, ...

) in northern

Anhui Anhui , (; formerly romanized as Anhwei) is a landlocked province of the People's Republic of China, part of the East China region. Its provincial capital and largest city is Hefei. The province is located across the basins of the Yangtze River ...

, China. It is similar to '' Paraplectronoceras'' except for having more strongly expanded siphuncular segments and less concave septa.

References

* Chen Jun-yuan et al., 197
Late Cambrian Cephalopods of North China -- Plectronocerida, Protactinocerida (Ord Nov) and Yanhecerida (Ord Nov)
* * Teicher, C. 1988. Main Feature of Cephalopod Evolution. ''in'' The Mollusca, volume 12, Paleontology and Neontology of Cephalopods. Clark and Trueman (eds). Academic Press.
Paleobiology DB - Jiagouceras
{{Taxonbar, from=Q6191424 Prehistoric nautiloid genera