Hypothesis (Pls answer with IF and THEN) How does fossil evidence determine the relationships of whale ancestors and their descendants?

Answer;

Similarities in the bone structure, the genetic composition, chemistry of the teeth etc

Explanation;Fossils are the trace or remains of an organism that lived long ago. Fossils provides a lot of evidence concerning the ancestors of whales.Fossil evidence shows that a land mammal the lived between 50 million and 70 million years ago. It is thought that whales evolved from these ocean-dwelling mammals.Whales Descended From Tiny Deer-like Ancestors. Scientists found that whales are mammals whose ancestors walked on land.The structures of the bones and chemistry of the teeth of a close relatives of whales such as Indohyus,indicates that they spent most of their time in water.

They are both used to view parts of the cell