Chinese and American scientists discovered lichen fossils dating back to about 600 million years ago in a black phosphate rock at Weng'an Phosphate Mine in southwest China's Guizhou Province, according to Nanjing Institute of Geology and Palaeontology of Chinese Academy of Sciences on May 13. They are regarded as the most primitive lichens on the earth.

The important achievement was jointly made by Yuan Xunlai from Nanjing Institute of Geology and Palaeontology, Dr. Xiao Shuhai from Virginia Polytechnic Institute & State University and T. N. Taylor from the University of Kansas. Their discovery has been published on the US Science magazine issued on May 13, 2005.

Before that, the science circles have determined that the most ancient lichen fossils are in Scotland, 400 million years from now.

The new findings pushed the emergence of lichen back to 600 million years, marking a great progress in scientific research on early life on the globe.

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Colorful marks resembling petal on the bare rocks on the earth surface, they are what we call "lichen".

Lichen is the symbiosis of fungi and algae (mainly blue-green algae and green algae). Algae are capable of photosynthesis thus provide nutrition for fungi and themselves. Fungi absorb moisture and inorganic salt to meet the demands of algae for survival.

Adaptive to various extreme conditions, lichen is the pioneer in transforming the terrestrial parts of the earth surface.

During the 4.6 billion years' history of the earth, sea is known to have been there for 3.8 billion years and advanced plant 430 million years. 600 million years ago, the earth surface was probably an endless expanse with no life, just like the Mars.

Lichens that have multiplied in shallow sea, gradually moved on shore and the acid they produced eroded the minerals in rocks, thus provided soil for the advanced plants on the land to grow. From then on, the terrestrial parts of the earth, like sea, gradually transformed into a diverse world full of vitality.