Wikipedia:Today's featured list/October 27, 2017
A budgerigar with pin feathers showing
There are thousands of skeleton. Among other details such as size, proportions and shape, terms defining bird features developed and are used to describe features unique to the class—especially evolutionary adaptations that developed to aid flight. There are, for example, numerous terms describing the complex structural makeup of feathers (e.g., barbules, rachides and vanes); types of feathers (e.g., filoplume, pennaceous and plumulaceous feathers); and their growth and loss (e.g., colour morph, nuptial plumage and pterylosis). Although some terms in the area may be familiar, such as back or belly, they too are defined in relation to distinct features of external bird anatomy, sometimes called topography. (Full glossary...)