FOSSILIZATION OF FEATHERS

Scanning electron microscopy of feathers has revealed evidence that a bacterial glycocalyx (a network of exocellular polysaccharide fibers) played a role in promoting their fossilization in some cases. This mod e of preservation has not been reported in other soft tissues. The maj ority of fossil feathers are preserved as carbonized traces. More rare ly, bacteria on the surface are replicated by authigenic minerals (bac terial autolithification). The feathers of Archaeopteryx are preserved mainly by imprintation following early lithification of the substrate and decay of the feather. Lacustrine settings provide the most import ant taphonomic window for feather preservation. Preservation in terres trial and normal-marine settings involves very different processes (in amber and in authigenically mineralized coprolites, respectively). Th erefore, there mag be a significant bias in the avian fossil record in favor of inland water habitats.