A scientist wants to determine the age of a rock. The rock contains an index fossil and an ancient relative of a living organism. Which is more useful for dating the rock, and why?

an ancient relative of a living organism would be more useful for dating the rock because fossils in a rock layer represent what lived during the period the rock was deposited.

Ancient Relative of a living organism

Explanation: Ancient Relative because by using the index fossil, you are also using the law of superposition. This law does not give you an accurate/specific date but instead the order they are in (i.e me saying i am older than my siblings compared to me saying i am 2 years older than them). By using an ancient relative of a living thing then we can see its phylogenic tree and measure around how old it is. Fossils also hold carbon and chemicals in there bones which allows us to use carbon dating. Carbon dating is an accurate way of measuring age.

an adaptation is a change or process by which an organism takes to be better suited for its environment. for example; migration is a behavioral adaptation, this is needed because birds are not built to last extremely cold climates. there are different adaptations because there are different species needing to adjust to different things, bears don't migrate; they hibernate.