Millions of years ago, the ancestors of all kangaroos lived in trees. They evolved to live on the ground, but the ancestors of tree kangaroos split from that lineage and headed back up into the forest canopy. To survive high off the ground, they underwent striking physical adaptations.

Tree kangaroos are predominantly solitary, nocturnal, and slow-moving herbivores. They spend up to 60% of their time sleeping curled up in branches to conserve energy. Their diet consists mostly of tough forest leaves, ferns, moss, and bark, which their large intestines break down slowly via specialized fermentation. 

Tree kangaroos are found primarily on the island of New Guinea (divided between Papua New Guinea and West Papua, Indonesia). A few species also live in the tropical rainforests of Northeastern Australia (Queensland). They inhabit dense tropical rainforests, lowland jungles, and high-altitude cloud forests up to 11,000 feet above sea level.