Pennaceous feathers are also known as contour feathers. This type of feather is present in most modern birds and has been shown in some species of maniraptoran 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 central shaft (or rachis) with vanes or vaxillum spreading to either side. These vanes are composed of a high number of flattened barbs, that are connected to one another with barbules.
The barbules are tiny strands that criss-cross on the flattened side s of the barbs. This forms a kind of miniature velcro-like mesh that holds all the barbs together, stabilizing the vanes.
Flight feathers (remiges and rectrices) are specialized types of pennaceous feathers, adapted for high loadings and often strongly asymmetric for improved flight performance.