CARBONIZATION
Carbonization refers to fossils being preserved as dark-colored, flattened, carbon-rich films. Most fossil leaves in the rock record have been carbonized. But, any fossil that's been preserved as a dark, flattened film can be called carbonized.
Carbonized fossil ferns on Pennsylvanian-aged, gray mudshale (10.6 cm across).
Tetragraptus (Hemichordata, Graptolithina, Graptoloidea), preserved by carbonization on cream-colored clayshale (field of view 5.5 cm across). Most graptolite fossils are preserved as carbonized films.
Stratigraphy: Bendigonian Formation, Lower Ordovician
Locality: Spring Gully, Bendigo, Victoria, Australia