LAUSR

ABSTRACT Numerous tooth plates of different types were recovered from the Upper Triassic Tiki Formation of India. Sharp crested tooth plates with five acute ridges, tubercles on the crests, robust and deep furrows, wide spaces between successive ridges and reticulate ornamentation on the occlusal surfaces are assigned to a new species of the dipnoan genus Ptychoceratodus. Another tooth plate, characterized by four ridges with conical and cusplet-like denticles is identified as a Gnathorhiza. This is the first record of gnathorhizid fishes from the Upper Triassic sediments around the world. The Tiki aquatic realm was inhabited by different types of fishes including freshwater sharks, omnivorous/carnivorous dipnoans and other bony fishes. Palaeobiogeographic distribution of the dipnoans suggests that these were restricted to a high palaeolatitude in the southern hemisphere, where co-occurrences of several genera are seen in India.