The stromatolites of the Precambrian Aravalli Supergroup outcropping around Udaipur, Rajasthan, India are classified into two distinct lithofacies: the older carbonate stromatolites facies and the younger phosphate-bearing stromatolite facies. Phosphate-bearing stromatolites of the same age have been reported from China, Russia and Australia. The phosphate-bearing stromatolites of Udaipur show fossil cyanobacteria. These cyanobacteria grew luxuriantly in the absence of any competitors and accumulated abnormal amounts of phosphorus from the novo phosphorus-rich environment, eventually forming a workable phosphate deposit owing to their post-mortem alteration. There is a sharp and abrupt contact between the two facies. This sharp contact or diastem underlying the phosphate-bearing stromatolites is of extreme importance as it denotes a stratigraphic hiatus characterizing a period of overall change in the environment. This change could be due to some catastrophic episode. The Earth during its geologic history has been subjected to several such episodes caused by certain high-energy events, such as impacts by extraterrestrial bodies. These impacts caused mass extinctions as occurred at the Permian–Triassic or Cretaceous–Tertiary boundary or the emergence of new flora and fauna as occurred at the Precambrian–Cambrian boundary. It is therefore argued that the diastem noted between carbonate and phosphate-bearing stromatolites is possibly due to an impact that inundated the Earth with phosphorus. Phosphorus is a key constituent of proteins, which are the major repository of chemical energy for metabolism. Its abundance after this event triggered the emergence of new advanced species.