Beijing, Mar 17 (IANS): Researchers from China, New Zealand and the US have found four intact mushroom fossils, sources said on Friday.

The four, well preserved in Burmese amber (fossilised sap of extinct trees) for at least 99 million years, are the earliest complete mushroom fossils ever found, according to the sources with the Chinese Academy of Sciences.

The findings represent four species of mushroom. A stalk and a complete cap containing distinct gills are visible in most of the mushrooms, which are two to three mm long, Xinhua news agency reported.

The research team led by professor Huang Diying from Nanjing Institute of Geology and Paleontology, reported the finding after researching more than 20,000 pieces of Burmese amber collected over 10 years.

The discovery highlights the palaeo-diversity of mushrooms, pushing back the presence of agaric mushrooms by at least 25 million years.

Mushrooms are common and morphologically diverse fungi. Their bodies are soft and ephemeral and therefore extremely rare in fossils.

Until the recent discovery, only five species of mushrooms were known exclusively from amber.