For decades, scientists have debated the origin of the iridescence seen in some fossil feathers. Some have argued that the colors are due to the presence of bacteria, while others have suggested that the colors are due to the preservation of pigment molecules within the feathers.
In a new study, published in the journal Nature Communications, researchers from the University of Bristol and the University of Manchester re-examined the evidence for both hypotheses. They used a variety of techniques, including scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy, to analyze fossil feathers from a variety of different species.
Their results showed that the iridescence in fossil feathers is not associated with the presence of bacteria. Instead, they found that the colors are due to the preservation of pigment molecules within the feathers. These pigments are called melanosomes, and they are the same pigments that give modern feathers their color.
The researchers suggest that the iridescence in fossil feathers is due to the way that the melanosomes are arranged within the feathers. The melanosomes are arranged in a way that scatters light, creating the iridescent colors.
This study has important implications for our understanding of the evolution of feathers. It suggests that the ability to produce iridescent colors evolved early in the evolution of feathers, and that this ability was not dependent on the presence of bacteria.
The study also has implications for the interpretation of fossil records. The presence of iridescent colors in fossil feathers can no longer be used as evidence for the presence of bacteria. Instead, it can be used as evidence for the preservation of pigment molecules within the feathers.
