Fossil of the oldest country dweller discovered

Preserved mushroom is 440 million years old

440 million years old: mycelium filaments of Tortotubus © Martin Smith
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Fossil with rarity value: It is not only the oldest known conserved specimen of a fungus, but also the oldest fossil of a terrestrial organism that has been identified by a researcher: The 440 million year old find of a fossilized fungus mycelium thus closes a significant gap the evolution of these eukaryotic creatures - and in the evolution of life on land.

For almost a billion years, life took place exclusively in the oceans. When exactly the first life forms of water came ashore, is difficult to understand today. Fossil finds that could prove that are rare. Nevertheless, scientists agree that the transition began in the early Paleozoic, about 500 to 450 million years ago.

Before complex organisms could develop on land, conditions had to be created first. Mushrooms played an important role here: they were able to start rotting processes while producing important nutrients. Only through them could layers of fertile soil develop in which plants could grow, which in turn made animal life possible.

The researcher Martin Smith of Durham University has now discovered such a pioneer of rural life - a find that is unique in two ways.

Important puzzle piece

For his study, Smith examined a variety of tiny fossils from Sweden and Scotland, which had been found in the 1980s. He found that the fossils, which are each smaller than the diameter of a hair, are 440 million years old and belong to mycelia of the fungus Tortotubus protuberans. display

Thus, the find is not only the oldest example of a fossil fungus, but also the oldest known fossil of a land-living organism at all. "The find thus fills a significant gap in the evolution of fungi and also in the evolution of life on land, " says Smith.

Modern structures

According to Smith, the mycelium of tortotubus is already similar in structure to the root-like mesh of microscopic filaments that some modern fungi typically form in the soil. Because the fossils show the fungus in different stages of growth, they also allow more conclusions. For example, Smith's growth pattern is somewhat similar to mushrooms.

"Even though there is no clear evidence for caparis mushrooms from the Paleozoic era, it could be that cap mushrooms already colonized the land before the first animals left the oceans, " he speculates.

Decomposition of bacteria?

However, one question remains: what then on land could Tortotubus decompose to make a contribution to the establishment of complex creatures ashore? Smith taps bacteria or algae. However, fossil evidence is also rare among these organisms. (Botanical Journal of the Linnean Society, 2016; doi: 10.1111 / boj.12389)

(Botanical Journal of the Linnean Society, University of Cambridge, 02.03.2016 - DAL)