67 ma - 67 Million years ago
Death of the icons. A T. rex and a Triceratops died and were rapidly buried together in a single grave, preserving their bones and tissues in life position, allowing for complete fossilization. Their bodies turned to skeletons, and then fossil. It is incredibly rare for even one complete articulated skeleton to be preserved let alone two together. For both these iconic specimens to be preserved intact for 67 million years is the rarest of the rare.