GMAT Critical Reasoning
Since at least 1868, paleontologists have been arguing over whether or not birds evolved from dinosaurs. In the late 1960s, a scientist from Yale University named John Ostrom declared there were 22 features in the skeletons of meat-eating dinosaurs that were also seen in birds but not in any other animals. By the year 2000, 85 such characteristics unique to dinosaurs and birds had been discovered. Some very vocal critics continue to oppose the theory, but this skeletal evidence strongly supports the idea that dinosaurs are the direct ancestors of modern birds.
Which of the following, if true, would allow the conclusion of the argument to be more properly drawn?
- A It is impossible to tell for certain by examining the fossil record whether dinosaurs were warmblooded like birds or cold-blooded like reptiles.
- B Therapod dinosaurs evolved feathers in place of scales because feathers conferred greater protection against the cold.
- C The existence of so many uniquely linked characteristics cannot be explained by convergent evolution, the development of similarities in separate lineages through the operation of similar selective factors on both lines.
- D Several of the supporters of the theory that birds evolved from dinosaurs are paleontologists who are highly regarded in their field.
- E The earliest "feathered dinosaur" fossil found has been dated at 129 million years old, while the earliest "true bird" fossil has been dated at 150 million years old.
Correct Answer: C