A pair of gray foxes (Urocyon cinereoargenteus) is at home in a tall ironwood tree, high above the Sonoran Desert floor. The species first evolved more than 7 million years ago in the lush tropical forests that once covered what is today’s American Southwest. Since that time, this anatomically distinct fox has accumulated an impressive array of un-fox-like adaptations for life in the canopy, including primate-like flexible wrists and cat-like paws with long, curved claws that allow it to grip tree branches. This arsenal allows this uniquely arboreal fox species to sneak up on birds roosting near the tips of branches and to drag heavy objects—here, the skeleton of a fawn—into the canopy. Fox pairs use the skeletons as pungent scent posts to mark their territories. Particularly after rain, the smell of these “skeleton trees” can be quite powerful and can carry great distances.