Question

evidence for evolution: fossils
transitional forms in the fossil record provide evidence for evolution. these are organisms that are an intermediate between two species. there are many examples of transitional forms in the fossil record, including for the gray whale.
pakicetus (50 million years ago)
aetiocetus (25 million years ago)
gray whale (present day)

1. position a red arrow to point out the nostrils in each organism.
2. what do you notice happening to the nostril position over time? how does this provide evidence of evolution?

Explanation:

1. For the first sub - question, one would need to visually identify and mark the nostril location on each of the given skulls (Pakicetus, Aetiocetus, Gray Whale).
2. For the second sub - question, over time, the nostril position moves from the front of the snout (in Pakicetus) towards the top of the head (in the modern gray whale). This is evidence of evolution as it shows an adaptation to an aquatic lifestyle. As whales became more fully aquatic, having nostrils on the top of the head (blowholes) allowed for easier breathing at the water's surface without having to fully raise the head out of the water.

Answer:

1. This requires visual marking on the image which cannot be done in text form.
2. The nostril position moves from the front of the snout to the top of the head. This is evidence of evolution as it is an adaptation to an aquatic lifestyle for easier breathing at the water's surface.