AP BIOLOGY

Detailed explanation-1: -Intermediate fossil forms serve as the transitional stage between the ancestral form and its living descendants. These transitional fossils show how organisms have changed over time. For example, the Aetiocetus is the intermediate form between the modern gray whales and its ancestors, which are called Pakicetus.

Detailed explanation-2: -A fossil that shows an intermediate state between an ancestral trait and that of its later descendants is said to bear a transitional feature. The fossil record includes many examples of transitional features, providing an abundance of evidence for evolutionary change over time.

Detailed explanation-3: -Fossils are the preserved remains or traces of animals, plants, and other organisms from the past. Fossils are important evidence for evolution because they show that life on earth was once different from life found on earth today.

Detailed explanation-4: -Fossils document the existence of now-extinct species, showing that different organisms have lived on Earth during different periods of the planet’s history. They can also help scientists reconstruct the evolutionary histories of present-day species.

Detailed explanation-5: -A transitional fossil is any fossilized remains of a life form that exhibits traits common to both an ancestral group and its derived descendant group.