North American porcupines are large rodents whose ancestors apparently crossed from Africa to South America on floating trees and logs some 30 million years ago. Their most prominent feature are the approximately 30,000 quills which grow individually everywhere out of the skin musculature, interspersed with bristles, under fur and hair.
The quills help the porcupine defend themselves from attacks by predators. The only quill free areas are the face and underside. » Continue Reading.