Feathers evolved in theropod dinosaurs prior to the evolution of birds like Archaeopteryx. Several feathered dinosaur fossils have been discovered, including Sinosauropteryx which had down-like feathers and Caudipteryx which had vaned feathers on its tail and limbs. While early feathers included simpler filamentous structures, vaned feathers similar to modern feathers had evolved in dinosaurs like Microraptor gui which had wings with asymmetrical feathers. Feathers are believed to have evolved from scales to aid with temperature regulation before being adapted for flight.

2. Advanced Ornithology
by
Maryam Riasat
EVOLUTION OF FEATHERS

3. Evolution of feathers
 Feathers are the defining characteristic of
birds
 Well developed feathers of Archaeopteryx
separated it from dinosaurs
 Later discoveries revealed that feathers and
featherlike structures are not unique to birds
 Theropods dinosaurs had them also

4. Feathered Dinosaurs
• Chicken sized Sinosauropteryx with
filamentous downlike feathers
• Caudipteryx with a well preserved fan of
vaned feathers on its tail and forelimbs
• More than a dozen fossil feathers of theropod
dinosaurus and dromaeosaurs have now been
found that are not closely related to
Archaeopteryx

6.  Ancient feathers included
downlike filamentous structures
or dino-fuzz and well-vaned, that
are essential modern feather structure
 The relation of dino-fuzz to real
feathers remains controversial
Arguments range from their being
unrelated structures to being precursors
of feathers

7.  Less controversial are the well preserved
vaned feathers
 A little dinosaur named Microraptor gui had
front and hind wings that sported outer
feathers with asymmetrical vanes just as in
the wings of modern flying birds
 Feathers clearly evolved in the modern form
in theropod dinosaurs and then diversified in
form and function

9.  It is believed that feathers evolved from scales
of some kind
 Feathers evolved not as modified scales but
as a novel epidermal structure
o A hypothesis long favored by reptile experts
is: Even if the feathers evolved from scales,
they were likely aided temperature regulation
as insulation or heat shields

10.  Feathers did not evolve initially in concert
with the evolution of flight
 Rather avian flight followed the initial
evoltion of vaned feathers
 Gliding and weak flapping flight fostered
additional changes in feather form and
function on the wings and tail