A new microcoprolite assemblage from the Upper Triassic Tiki Formation of India: ichnotaxonomy, and producer association(s)

We record the first occurrence of a microcoprolite assemblage from the Upper Triassic Tiki Formation, Son – Mahanadi Basin, India. The microcoprolite assemblage has been assigned to four new ichnotaxa namely <i>Cylindrocopros gondwanensis</i> igen. et isp. nov., <i>Elliptocopros rewaensis</i> igen. et isp. nov., <i>Convolucopros shadolensis</i> igen. et isp. nov., and <i>Cylindribulbocopros triassicus</i> igen. et isp. nov. based on their external morphology, internal texture, and geochemical composition. Geochemical techniques confirm the phosphatic nature of the microcoprolites recorded from the Tiki Formation. Taken together, the associated fauna and the morphological comparisons between previously known coprolites from the Mesozoic-Cenozoic sedimentary sequences suggest that the Tiki microcoprolites were likely produced by carnivorous actinopterygians. The dentalites or biting traces observed on the external surface of the ichnotaxa recorded herein are the oldest records from the subcontinent. SEM analysis reveals the dominant presence of egg-like mineral spheres ‘microspherulites’, needle- and rod-shaped apatite crystals; however, the microcoprolites are devoid of biotic (floral and faunal) inclusions. Considering the abiotic crystals and geochemistry, we infer that the original faecal matter most likely underwent rapid precipitation during the early phase of mineralisation and had a very high potential for fossilisation.