Marwick, J. 1960 Early Tertiary Mollusca from Otaio Gorge, South Canterbury. Wellington: New Zealand Geological Survey. New Zealand Geological Survey paleontological bulletin 33. 31 p.
Abstract: The molluscan faunule from Otaio Gorge is closely related to the Matau faunule of Kaitangata, and is intermediate in age between the Wangaloan and the Bortonian. Having more affinity with the Bortonian, the beds are correlated with the upper part of the Dannevirke Series (perhaps lower Mid-Eocene). Thirty genera are represented; of the 33 species or subspecies at least 18 are new, but only 14 have been named here. Nine genera are known to range back to the pre-Bortonian, and of these, Colposigma and the primitive struthiolarid, Perissodonta , were previously known in New Zealand only from the Wangaloan. On the other hand, Longimactra (except for one Duntroonian occurrence) and Paphirus were previously known only from the Pliocene to Recent. The fossils are in hard, concretionary bands in marine sands about 100 ft stratigraphically below fossiliferous Bortonian and overlie quartzose coal measures that rest on basement greywacke. (auth)