416 24 OCTOBER 2014 • VOL 346 ISSUE 6208 sciencemag.org SCIENCE
By Marie-Claire Koschowitz,1,2 Christian
Fischer,2 and Martin Sander1,3
Once believed to be a diagnostic feature of birds, feathers are now known to have evolved in dinosaurs well before the first birds. In birds, feathers serve several functions: Down feathers insulate the body,
whereas planar or pennaceous feathers are
necessary for flight, communication, camouflage, and brooding (see the first figure).
What was their original function in non-avian dinosaurs? Based on a specimen of
Archaeopteryx that preserves a spectacular
plumage of pennaceous feathers, Foth et al.
(1) recently hypothesized that pennaceous
feathers did not evolve for flight but for
display. Together with insights into body
size evolution in dinosaurs along the line to
birds (2) and the discovery of protofeathers
in early dinosaurs (3), these results contribute to an emerging understanding of why
pennaceous feathers may have been superior to filamentous protofeathers.
Protofeathers presumably evolved in
early dinosaurs (see the second figure) (4).
Their main function must have been to insulate, because an increase in growth rate
was facilitated by a faster metabolism early
1Division of Paleontology, Steinmann Institute for Geology,
Mineralogy and Paleontology, University of Bonn, Nussallee 8,
53115 Bonn, Germany. 2Institute for Zoology and Anthropology,
Department of Morphology, Systematics and Evolutionary
Biology with Zoological Museum, Georg-August-Universität
Göttingen, Berliner Strasse 28, 37073 Goettingen, Germany.
3Natural History Museum of Los Angeles County, 900
Exposition Boulevard, Los Angeles, CA 90007, USA. E-mail:
Dinosaur color vision
may have been key to the
evolution of bird feathers
(Acryllium vulturinum) plumage.
Structural colors like blue
and violet are displayed in concert
with intricate, high-resolution
ornamentation. The close-up
shows a specimen in the collection
of the Museum Alexander Koenig.
The full-size bird is from
the Zoological Museum of the
University of Göttingen.
Good sex for ferns is all
about signal timing p. 423
Any hope for ocean
wildlife? p. 420