Researchers in Yunnan Province, southern China, have described a newly identified giant fungus nicknamed "D-rex," whose fruiting bodies can grow to roughly 50 centimeters tall and weigh about 2.2 kilograms — making it the largest known species in the phylum Ascomycota, one of the two major branches of the fungal kingdom.
Formally named Dianjunus rex, the fungus grows from fallen wood and the roots of recently dead trees. Its discoverers placed it in a brand-new family, Dianjunaceae, in a study published in Frontiers in Fungal Biology. A molecular-clock analysis, which estimates evolutionary age by comparing mutation rates against fungi of known lineage, traced the species' origin to roughly 65 million years ago, right around the mass extinction that wiped out the dinosaurs.
The researchers suggest the fungus may have thrived on the surge of dead plant material left behind after that extinction event, though they are careful to note the timing link is an inference drawn from the molecular dating, not direct fossil evidence tying the fungus to the extinction itself. Whatever its exact origin story, D-rex's sheer size has made it an instant standout even among a kingdom known for producing some of the largest living organisms on Earth.
