Marine Mushrooms Popping Up 100 Million Years Before Cambrian Explosion

Fossilized steroids show that there were mushrooms belonging to the animal kingdom in marine environments at least 100 million years prior to the Cambrian explosion that gave rise to a variety of animal species and organisms. The new finding supports previous research, whose conclusions were not accepted at the time by the scientific community.

Credit; Uppsala University

The most common type of fossils are residues of body parts from animals and parts of smaller organisms, but there are also fossils of chemical compounds and molecules. These can be called biomarkers. Steroids are a type of chemical compound that are ideal chemical biomarkers because they can be preserved for hundreds of millions of years, especially in petroleum and bitumen. In addition, these steroids are produced only by specific groups of organisms and can thus be used to study the development of life on earth.

Phylogenetic analyzes (analyzes showing how organisms are related to each other based on similarities in their DNA sequences) show that fungal animals are the first animals that occurred on our planet during the period of time neoproterozoic (more than 600 million years ago). By contrast, mushroom fossils have only been found from the Cambrian explosion that occurred about 540 million years ago.

In 2009, Gordon Love and his partners found a 717-635 million year old fossil of a steroid (24-isopropylcholestanes) produced by fungal animals living today (Love et al., 2009, Nature). This finding shows that animals were on earth earlier than previously thought, a conclusion that was not accepted by the rest of the scientific community.

A group of researchers from UC Riverside in the United States and Uppsala University, together with colleagues from several other universities in the United States and Australia, have found another fossil of a steroid biomarker (26 methyl stigmastanes). The results are now published in Nature Ecology & Evolution.

- We, like previous studies, show that steroids can be used as biomarkers from fungal animals. In addition, our findings support previous findings that animals were already present under neoproterozoicum, “said Paco Cárdenas, pharmacologist at Uppsala University.

Another important aspect of the article is that researchers were able to identify the existing fungal animals that produce the chemical compounds found as fossils. These fungi are found in the North Atlantic (also off the Swedish west coast) and the Pacific Ocean – in deep sea as well as in shallow tropical waters.

The study required a combination of paleogeochemistry and zoology and the fungus experts Paco Cardenas and Sunithi Gunasekera at Uppsala University contributed important knowledge, including the diversity and relativity of now living fungi. They also have access to a large collection of fungal samples for chemical analyzes.

Zumberge A., Love GD, Cárdenas P., Sperling EA, Gunasekera S., Rohrssen M., Grosjean E., Grotzinger JP and Summons RE (2018) Demosponge steroid biomarker 26-methylstigmastane provides evidence for Neoproterozoic animals. Nature Ecology & Evolution.

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Contacts and sources:
Paco Cárdenas
Uppsala University
Citation:    Demosponge steroid biomarker 26-methylstigmastane provides evidence for Neoproterozoic animal
Zumberge A., Love GD, Cárdenas P., Sperling EA, Gunasekera S., Rohrssen M., Grosjean E., Grotzinger JP and Summons RE (2018)s. Nature Ecology & Evolution.