Pennaceous feather Pennaceous feather The pennaceous feather is a type of feather present in most modern birds and in some other species of maniraptoriform dinosaurs. A pennaceous feather has a stalk or quill. Its basal part, called a "calamus", is embedded in the skin. The calamus is hollow and has pith formed from the dry remains of the feather pulp, and the calamus opens below by an "inferior umbilicus" and above by a "superior umbilicus". The stalk above the calamus is a solid "rachis" having an umbilical groove on its underside. Pennaceous feathers have a rachis with "vanes" or "vaxillum " spreading
A Donkey, 3 Rocks, and a Bird. facing one another. The donkey has a rock balanced on its back, while the bird is both standing on a rock and balancing one on its head. The donkey has surfaces decorations, including glyphs and figures, and is coated in polychrome bronze. The bird is coated in blue, green, orange, red and yellow. The sculpture measures approximately x x . Its base is made of exposed aggregate concrete and measures approximately x x . One plaque on the base reads, . Another reads, . Inscriptions near the donkey's crotch displays the artist's last name, a copyright symbol, and the year