Trilobites of the Middle Wuliuan (Miaolingian) from the Kunzam La (Parahio) Formation of the Sumna River Section, Spiti, Himalaya, and Its Biostratigraphic Significance

A 153.48 m thick section of the Kunzam La (Parahio) Formation exposed on the right bank of the Sumna River (Spiti), Himalaya (India), yielded Cambrian trilobites from two stratigraphic intervals. The lower interval yielded the trilobites Xingrenaspis cf. X. dardapurensis and Kunmingaspis stracheyi with a few brachiopods. This interval falls within unzoned 4 of the Cambrian of the Himalaya. The upper stratigraphic interval yielded Iranoleesia butes and an undetermined ptychopariid trilobite belonging to Hayden level 13. Based on faunal elements, the entire measured section is correlated with the Sunaspis laevis–Sunaspidella rara biozone to Metagraulos dolon biozone of the southern and western marginal parts of the Ordos basin (China) and belongs to the middle Wuliuan Stage (Miaolingian Series).