Nanostructures in this 40 million year-old feather once made it
iridescent. Credit: Jakob Vinther/Yale University
By using an electron microscope to examine nanoscale structures in a 40 million-year-old bird feather, researchers have determined that, in life, the birds were black with an iridescent, bluish-green coppery sheen, like starlings and grackles. The key to figuring this out was the discovery by researchers at Yale University that rod-shaped nanostructures in the feather specimens aren’t bacteria, but remnants of pigment-containing cells called melanosomes.
Iridescence in bird feathers is caused by
constructive interference of light scattered by the cells; how the light
scatters is determined by the arrangement of the melanosomes, which are preserved
not only in the bird fossils but in some dinosaur and mammalian ones as well.
The Yale researchers hope this technique could be used to get a better picture
of the coloring and patterning of dinosaurs and other extinct creatures. This
work is described online in the journal Biology Letters.