Imagine a scientist finds the fossils of an extinct Ichthyosaur and finds this morphological similarity of Ichthyosaurs and modern dolphins: bones indicating flippers and a tail for swimming. The scientist guesses that Ichthyosaurs may form a monophyletic group with the dolphins, based on this morphological similarity. What is one method or line of reasoning that scientists could not use when testing the hypothesis that dolphins and Ichthyosaurs form a monophyletic group?
A. Take blood samples and use DNA evidence to determine a more complete phylogenetic tree, because biologists have not successfully obtained DNA from Ichthyosaurs.
B. Collect more data about the presence and absence of many more characters of both dolphins and ichthyosaur bones.
C. Make sure that the flippers and tail in both Ichthyosaurs and dolphins are due to homology, rather than analogy.
D. See if the living sister group to dolphins is more closely related to dolphins than is the Ichthyosaur.
E. Use the principle of parsimony to decide which of several trees is most parsimonious.