October 2020 • Nebraskaland 25
Feathers are an engineering marvel.
Composed of the protein beta-keratin, they
have a central rachis (stem) that branches
into barbs and then barbules. The latter
have hooklets that interlock, like Velcro,
with nearby barbules. Modifications in the
branching pattern allow feathers to serve a
variety of functions.
Fluffy down feathers have flexible barbs
and long barbules that trap air and insulate
birds. Baby ducks, for instance, are born with
a complete coating of natal down to protect
against cold air and water. Due to their tightly
interlocking barbules, long wing feathers are
stiff, flat and air-proof — allowing birds to
fly. They are also anchored to wing bones by
ligaments for precise maneuverability and
strength. Bristles, often consisting of only a
stiff rachis, are the simplest feathers. These
frequently occur on the head where they
serve as protection or are uniquely colored or
shaped for display.
Recent fossil finds in China suggest the first
feathers appeared about 250 million years
ago in reptile ancestors of the dinosaurs. The
early dinosaurs likely had simple feathers
composed of hollow tubes, which served
to insulate and, if colored, to show off or
camouflage the warm-blooded creatures.
Feathers further evolved during the age of
dinosaurs. The tubes formed into clusters of
barbs, the base of these then fused to form
the rachis. Eventually barbules and hooklets
developed. Archaeopteryx, evolved from a
small flying dinosaur about 150 million years
ago and believed to be the first bird, arrived to
the party decked out in a diversity of feather
types.
Feather Biology
Though well-feathered and capable of fl ight, it is unknown whether Archaeopteryx was a fl apper or a glider.
GETTY
IMAGE
ILLUSTRATION
BY
ANDREW
LEACH,
CORNELL
LAB
OF
ORNITHOLOGY
ACADEMY.
ALLABOUTBIRDS.ORG
