This fossil turtle and this living hawk both have a structure in their neck called the atlas bone. What best explains why both species have an atlas bone? a) The turtle and hawk are different species, so they must not share an ancestor population. They inherited their atlas bone structure from separate ancestor populations.

b) The turtle and hawk both share the same ancestor population that had an atlas bone. They inherited this structure from the ancestor population.

c) It is impossible to say. Fossils are very old; therefore, we cannot make observations of the turtle’s ancestors, and we cannot explain its body structures.

d) All species have their own specific body structures, so it is a coincidence that this turtle and hawk each happen to have the atlas bone structure.