Melanin is a pigment responsible for the black-to-reddish-brown hues of many organisms including mammals and birds. It is packaged within cells in sausage-shaped organelles called melanosomes. Interestingly, melanosomes are well-preserved in many fossils including squid ink sacs and feathers. The image shows a colorized electron micrograph of melanosomes from a fossil feather. By comparing the shapes and concentrations of melanosomes in the cells of living bird feathers with those of fossil feathers, scientists are able to determine the most-likely colors and color intensities of extinct birds. The shape and concentration of the melanosomes in this fossil sample suggest that this region of the feather was intensely black in color.
The fossil feather was viewed in a scanning electron microscope and colored from the grayscale image with a computer. Each melanosome is approximately two micrometers long – about the size of a mitochondrion.
Jakob Vinther, PhD, Departments of Biological Sciences and Earth Sciences, University of Bristol, UK.