Which of the following patterns in the fossil record would be an example of an organism evolving through punctuated equilibrium?
A. dorsal fins appearing, disappearing, and reappearing in species of ancient aquatic reptiles, mammals, and fish
B. a species of flower changing in shape, followed by a change in the beak shape in its preferred species of pollinator
C. the shell shape of a species of snail remaining unchanged for millennia until it changes to an entirely different shape
D, whale species gradually changing from land-dwelling mammals that walked on four legs to marine mammals without legs
