Microraptor's World
Champsosaur skin impression
Notice the scales on the skin (around the "knee") and webbing
between the toes. The flesh appears like a ghostly halo, while the
vertebrae and other bones are sharp and three-dimensional. This
reflects the different ways in which hard parts (bone and teeth) and
soft tissue (such as skin and internal organs) are fossilized. Bones
become fossils as minerals replace organic structures on a molecular
level. In contrast, bacteria create the blurry traces of soft
tissue. As the bacteria consume skin, fur, feathers, and other soft
tissue, they leave metabolic deposits in the shapes of their meals.