A scientist was studying layers of earth in the side of a mountain. In the lower layers, she found fossils of reindeer and polar bears. In the upper layers, she found fossils of coyotes and squirrels. Which conclusion most likely explains the different fossils?
Group of answer choices

The climate was very cold in earlier time periods and became warmer in later time periods

The climate was very hot in earlier time periods and became colder in later time periods.

The climate was wet in earlier time periods and became drier in later time periods.

The climate was dry in earlier time periods and became wetter in later time periods.