Huge fungus in China may belong to a new family that emerged after dinosaurs vanished

A giant mushroom found in a tropical rainforest in Yunnan Province, China, may represent a previously unknown fungal family that evolved after the dinosaurs disappeared, according to researchers. The species, named Dianjunus rex, was identified in work reported Sept. 28 in Frontiers in Fungal Biology.

A fungus hidden in plain sight

The discovery began during a survey of fungal diversity in 2024, when local farmers alerted Chinese researchers to an unusual fungus in the area. According to the report, the farmers shared photos of the organism and wanted to know whether it was edible. When scientists visited the site, they found yellowish mushrooms growing from decaying tree roots in the rainforest.

The fungus belongs to the sac fungi, a group that includes morels, truffles and molds. Unlike the more familiar mushrooms many people buy or gather, these fungi make spores in microscopic structures, and their visible parts are fruiting bodies. In this case, those fruiting bodies were unusually large.

How big D. rex can grow

Researchers say the mushroom-like structures can reach about 50 centimeters tall and weigh as much as 2.2 kilograms. That makes them, by the team’s estimate, the largest spore-producing fruiting bodies known among sac fungi.

They described the mushrooms as yellowish and shaped somewhat like pillars, tentacles and spatulas. The size is especially notable because most sac fungi have much smaller fruiting bodies. A mycologist not involved in the work said the species appears to be the largest sac fungal fruiting body he is aware of, while noting that his experience has largely been limited to Europe.

What the DNA suggests

To place the fungus on the tree of life, the team compared its DNA with that of other fungi. The results suggest that D. rex is related to candlesnuff fungi and dead-man’s-fingers, but likely belongs in its own distinct family.

The researchers named the species Dianjunus rex, using the Latin word “rex” for king and a reference to the ancient Dian kingdom linked to the region where it was found. The report says the fungus may sit within a lineage that split from other fungi after the end-Cretaceous mass extinction, around 65 million years ago.

According to one researcher quoted in the article, fungi that break down dead organic matter may have had an advantage in the dark, cold period after the asteroid impact because they did not depend on sunlight the way photosynthesizers do.

Why the finding matters

If the interpretation holds, D. rex would not just be a large and unusual mushroom. It would also point to a deeper, older fungal lineage that survived and diversified after one of Earth’s great mass extinctions. That matters because fungi play a central role in recycling dead material in forests and soils, and their hidden diversity is still poorly known in many parts of the world.

• Location: tropical rainforest in Yunnan Province, southwestern China
• Type: sac fungus, or ascomycete
• Size: up to 50 centimeters tall and 2.2 kilograms
• Publication: Frontiers in Fungal Biology, Sept. 28
• Possible significance: may belong to a new fungal family that arose after the dinosaur extinction

The report also raises the possibility that other relatives of Dianjunus rex may still be undiscovered, perhaps known only from environmental DNA. For now, though, the fungus stands out as an unusually large and unexpected addition to the fungal family tree.

Source: Jake Buehler