Question

cetaceans are whales and their relatives. the diagram shows some fossils of cetaceans. fossils of some cetaceans fossils of some cetaceans which statement provides the best evidence that ambulocetus natans is an ancestor of basilosaurus isis? a homologous structures occur in each fossil. b similar nitrogenous bases are found in the dna of each fossil. c the fossils were found in different locations. d the youngest fossil is larger than the older fossils.

Explanation:

• Option A: Homologous structures are anatomical features that are similar in different organisms because they are inherited from a common ancestor. If homologous structures are present in the fossils of Ambulocetus natans and Basilosaurus isis, it provides strong evidence of a common ancestry.
• Option B: All living organisms (and by extension, their fossils) have DNA with the same four nitrogenous bases (adenine, thymine, cytosine, and guanine). This is a universal characteristic of life and does not specifically indicate a direct ancestor - descendant relationship between these two cetacean fossils.
• Option C: The location where fossils are found does not directly relate to whether one is an ancestor of the other. Fossils can be moved by geological processes (e.g., plate tectonics, erosion, sedimentation).
• Option D: The size of a fossil is not a reliable indicator of an ancestor - descendant relationship. Organisms can change in size for many reasons (e.g., changes in diet, habitat, evolutionary adaptations not related to direct ancestry) over time.

Answer:

A. Homologous structures occur in each fossil.