With rapid burial in a moist anoxic environment, such as the coal swamps of the Carboniferous period, carbonaceaous films of plant material like fern fronds may survive.

• 迅速埋藏于潮湿的缺氧环境下，正如媒在石炭纪沉没，类似蕨类植物的含碳植物材料即可能存活下来。