An artist's interpretation of the stem turtle, an ancestor of turtles that had not yet evolved a shell. (Rainer Schoch) An ancestor of modern-day turtles, a shell-less creature with a long tail once ...

An ancestor of modern-day turtles, a shell-less creature with a long tail once puttered around an ancient lake, likely munching on insects and worms with its peglike teeth, a new study finds.