It was once thought that cetaceans had evolved from an extinct group of mammals called the mesonychids. If, in the future, it is determined that some organisms currently classified as cetaceans did actually evolve from mesonychids, whereas other cetaceans evolved from artiodactyl stock, then what will be true of the order Cetacea?
A) It will be paraphyletic.
B) It will be polyphyletic.
C) It will need to be thrown out or modified if classification is to reflect evolutionary history.
D) Two of the responses are correct.

Question

Quizplus · Accepted Answer

Cetacea would be considered polyphyletic if its members evolved from two distinct ancestral groups (mesonychids and artiodactyls), and thus, the classification would need to be modified to accurately reflect evolutionary history.

It Was Once Thought That Cetaceans Had Evolved from an Extinct