The North American porcupine (Erethizon dorsatum), also known as the Canadian porcupine, is a large quill-covered rodent in the New World porcupine family. It is the second largest rodent in North America, after the North American beaver (Castor canadensis). The porcupine is a caviomorph rodent whose ancestors crossed the Atlantic from Africa to Brazil 30 million years ago, and then migrated to North America during the Great American Interchange after the Isthmus of Panama rose 3 million years ago.
The North American porcupine migrated from South America, where all New World porcupines or hystricomorphs evolved. Erethizon appeared in North America shortly after the two continents joined together in the later Tertiary period. Other hystricomorphs also migrated, but Erethizon was the only one to survive north of Mexico. No known fossils are attributed to hystricomorphs prior to the late Tertiary period. Some fossils, such as species from the family Paramyidae, show resemblance to the porcupine, but they are so primitive and generalized that they could be ancestors to all later rodents.
South American hystricomorphs first appeared in the Lower Oligocene period. They are thought to have migrated from Africa, ancestors of the Old World porcupines or Hystricidae or they originated based on a migration of the North American Paramyidae.
The earliest appearance of E. dorsatum is from the Pleistocene era found along the Arroyo del Cedazo near Aguascalientes, Mexico.
The individuals on this page were photographed in the Sacramento Mountains of southern New Mexico.
