The treepounce relies mainly on its hearing for hunting, and so its ears are highly developed. Tufts of hair-like feathers around the ear-opening funnel the sounds into the ear canal. In appearance the tufts resemble the fleshy external ears found on some small mammals. The coloring of the coat conceals the treepounce in the trees.

The Treepounce, Raminsidius jacksoni, is an arboreal, almost marten-like arbrosaur from the deciduous and mixed woodlands of North America, in The New Dinosaurs: An Alternative Evolution.

As on almost all the other continents, the arbrosaurs fill the trees of North America. Some eat insects, others consume fruit and berries, and some prey upon other arbrosaurs. The treepounce is one such carnivore. With a head and body reaching 70 centimeters (2 feet) it is larger than most of the arbrosaurs, and so it tends to be less agile. However, what it lacks in agility it makes up for in stealth. Lying along a branch on a sunny day its spotted feathered coat makes it almost invisible in dappled sunlight. With infinite patience it waits until an unsuspecting nauger, or another smaller arbrosaur scrambles close, and then pounces, making a quick kill.

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