Final answer:
The fact that a T. rex and triceratops found together in Montana and another T. rex found in Wyoming were in rocks of the same age exemplifies the principle of biostratigraphic correlation in geology.
Step-by-step explanation:
The discovery that a T. rex and triceratops were found buried together in Montana and a different T. rex was found in Wyoming in rock of the same age demonstrates the principle of biostratigraphic correlation. This principle is used by geologists and paleontologists to correlate age between different rock units that may not be physically connected but share similar fossil assemblages, indicating that they were deposited at the same time. Fossil correlation plays a crucial role in determining the ages of rock layers and understanding the geological timeline.