The kangaroo is one of the most commonly known marsupials. It lives throughout all of Australia and Tasmania. The kangaroo was first described in a report by James Cook who thought them to be "jumping dogs". In general the kangaroo eats leaves of shrubs, trees, and grasses. It belongs to the family macropodidae which means "big footed". There are twenty genera and one hundred and fifty species and subspecies. One of the fastest kangaroos is the gray kangaroo which can hop at about twenty-five miles per hour. By far the largest of them all is the sooty kangaroo coming in at six feet tall. With the biggest and fastest we must include the smallest which is the tiny musk kangaroo which is smaller than a common rabbit.