Question

Birds and reptiles are both vertebrates that lay eggs but birds have beaks and reptiles have teeth. Occasionally birds have teeth but only in the embryonic stage. Which conclusion is best supported by the presence of teeth in bird embryos?

A. Ancestors of reptiles had beaks similar to those of birds.
B. Birds and reptiles eat similar types of food.
C. Birds and reptiles share a common ancestor.
D. Modern reptiles are the ancestors of modern birds.

Answer 1

The answer is A, ancestors of reptiles had beaks similar to those of birds.

Answer 2

The conclusion that is best supported by the presence of teeth in bird embryos is that C. birds and reptiles share a common ancestor.
This common ancestor had teeth, which reptiles preserved, and birds only have in the embryonic stage.