Tiny musky rat-kangaroos hold the key to explain why 'roos hop

To understand why kangaroos hop -- a rarity among animals -- researchers have studied the musky rat-kangaroo (Hypsiprymnodon moschatus), a diminutive marsupial that weighs only 500 grams but is the last living representative of its family and part of a lineage that extends back to before kangaroos evolved their distinctive hopping gait.