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Dinosaur color vision and evolution of feathers

Ben Creisler

New papers:

How dinosaur color vision may have led to the evolution of pennaceous
feathers for display before feathers were adapted for flight:

Marie-Claire Koschowitz, Christian Fischer & Martin Sander (2014)
Beyond the rainbow.
Science 346 (6208): 416-418
DOI: 10.1126/science.1258957

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 nonavian dinosaurs? Based on a specimen
of Archaeopteryx that preserves a spectacular plumage of pennaceous
feathers, Foth et al. 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 and the
discovery of protofeathers in early dinosaurs, these results
contribute to an emerging understanding of why pennaceous feathers may
have been superior to filamentous protofeathers.


News and news release (in German)




Another recent paper about the structure of feathers:

In Open Accesss

Christian M. Laurent, Colin Palmer, Richard P. Boardman, Gareth Dyke
and Richard B. Cook (2014)
Nanomechanical properties of bird feather rachises: exploring
naturally occurring fibre reinforced laminar composites.
Journal of the Royal Society Interface 6 vol. 11 no. 101 20140961
doi: 10.1098/rsif.2014.0961


Flight feathers have evolved under selective pressures to be
sufficiently light and strong enough to cope with the stresses of
flight. The feather shaft (rachis) must resist these stresses and is
fundamental to this mode of locomotion. Relatively little work has
been done on rachis morphology, especially from a mechanical
perspective and never at the nanoscale. Nano-indentation is a
cornerstone technique in materials testing. Here we use this technique
to make use of differentially oriented fibres and their resulting
mechanical anisotropy. The rachis is established as a multi-layered
fibrous composite material with varying laminar properties in three
feathers of birds with markedly different flight styles; the Mute Swan
(Cygnus olor), the Bald Eagle (Haliaeetus leucocephalus) and the
partridge (Perdix perdix). These birds were chosen not just because
they are from different clades and have different flight styles, but
because they have feathers large enough to gain meaningful results
from nano-indentation. Results from our initial datasets indicate that
the proportions and orientation of the laminae are not fixed and may
vary either in order to cope with the stresses of flight particular to
the bird or with phylogenetic lineage.

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