''Ninadiscus'' Korobov, 1980, is a genus of Eodiscinid trilobite belonging to the family Weymouthiidae Kobayashi (1943), Order Agnostida Salter (1864). SALTER, J. W. 1864: On some new fossils from the ''Lingula''-flags of Wales. ''Quarterly Journal of the Geological Society of London'', 20, 233–241. It lived during the

Botomian Cambrian Stage 4 is the still unnamed fourth stage of the Cambrian and the upper stage of Cambrian Series 2. It follows Cambrian Stage 3 and lies below the Wuliuan. The lower boundary has not been formally defined by the International Commission on ...

Stage = late Lower Cambrian Stage 4 (upper of two stages subdividing the un-named Series 2); the upper Botomian boundary corresponds to the base of the Middle Cambrian, the

Miaolingian The Miaolingian is the third Series of the Cambrian Period, and was formally named in 2018. It lasted from about to million years ago and is divided in ascending order into 3 stages: the Wuliuan, Drumian, and Guzhangian. The Miaolingian is prec ...

Series and

Wuliuan The Wuliuan stage is the fifth stage of the Cambrian, and the first stage of the Miaolingian Series of the Cambrian. It was formally defined by the ICS in 2018. Its base is defined by the first appearance of the trilobite species ''Oryctocephalu ...

Stage.

Distribution

''Ninadiscus'' is known from the Lower Cambrian (Botomian) of northwestern Mongolia (Egyngolskaya Suite) and the USA (New York). WHITTINGTON, H. B. ''et al''., Part O, Treatise on Invertebrate Paleontology. Revised, Volume 1 – Trilobita – Introduction, Order Agnostida, Order Redlichiida. 1997

Description

Like all Weymouthiidae, ''Ninadiscus'' lacks eyes and facial sutures, with the glabella tapering gently forward, rounded frontally and extending to the anterior border furrow. The cephalic border is broad frontally (sag.), bears three transversely arranged tubercles and narrows markedly towards posterior. Posterior cephalic margin is straight (tr.) and merely angulate abaxially. The occipital ring (L0) is short (sag). L1 is swollen and well-rounded. Two transglabellar furrows (S1 and S2) are well impressed (maximum cephalic width opposite S1). L2 is shorter than the frontal glabellar lobe (L3). Thorax unknown. The long and narrow pygidial axis is composed of 10 rings and almost reaches the posterior margin. The pleural fields are smooth and the pygidial border is absent except anteriorly.

References

Cambrian trilobites Weymouthiidae Agnostida genera Animals described in 1980 Cambrian trilobites of North America {{agnostida-stub Cambrian genus extinctions