Anomaly 1. Contrary to the popular belief that mammals do not regenerate lost digits like the "lower" vertebrates, not only do mice regrow the tips of their foretoes, but young humans can regrow cosmetically perfect fingertips. However, the amputation cannot be too far back, and herein lies the second anomaly.
Anomaly 2. Foretoe regeneration in mice is astoundingly sensitive to the site of amputation. Move the site only 0.2 0.3 millimeters farther back and no regrowth will occur. No one understands why such a tiny change in distance completely changes the body's response.
(Borgens, Richard B.; "Mice Regrow the Tips of Their Foretoes," Science, 217:747, 1982.)
