We compare melanosomes within feathers of extant chickens with patterns induced by microbial overgrowth on the same feathers, using scanning (SEM), field emission (FESEM) and transmission (TEM) electron microscopy. Melanosomes are always internal, embedded in a morphologically distinct keratinous matrix. Conversely, microbes grow across the surface of feathers in continuous layers, more consistent with published images from fossil feathers.
We compare our results to both published literature and new data from a fossil feather ascribed to Gansus yumenensis (ANSP 23403).
“Mouldic impressions” were observed in association with both the feather and sediment grains, supporting a microbial origin. PR