Cambrian trilobite fauna of the Haydenaspis parvatya level (Series 2, Stage 4): Its stratigraphic position with respect to the Oryctocephalus indicus Biozone (Miaolingian Series, Wuliuan Stage) in the Spiti Himalaya, India

Refinement of the Cambrian biozonation in the Parahio valley, Spiti region (Himalaya) leads to the demarcation of the stratigraphic distance between the Haydenaspis parvatya level (Series 2, Stage 4) and the Oryctocephalus indicus Biozone (base of the Miaolingian Series, Wuliuan Stage), which has been a subject of debate. The present work suggests that these two trilobite beds in the Kaltarbo section are separated by 183.4m of strata. Whether either taxon ranges beyond the beds they are found in this section or others in the Parahio Valley is yet unknown.