— Cora Wieneke, Mount Horeb, Wis. A Erin Flynn, conservation education curator at Henry Vilas Zoo in Madison, Wis.: Squirrels, beavers, chipmunks and rabbits all have similarly shaped teeth because ...
A rendering of Clavusodens mcginnisi, or “McGinnis’ nail tooth,” an ancient shark that stalked the ocean floor 340 million years ago. Rendering courtesy of the National Park Service A shark no larger ...