As the dinosaurs disappeared around 66 million years ago, other forms of life adapted to a changing planet. A giant fungus recently identified in China is offering scientists new insights into fungal evolution and the remarkable biodiversity that remains undiscovered.
A newly identified fungus discovered in the forests of Yunnan province in southwestern China is drawing scientific interest due to its remarkable size and evolutionary background. Designated as Dianjunus rex, this species generates vertical reproductive organs capable of growing up to roughly 20 inches (50 centimeters) tall while tipping the scales at close to 5 pounds (2.2 kilograms).
Its name draws a parallel to Tyrannosaurus rex, the well-known dinosaur frequently dubbed the monarch of ancient predators. Even though both organisms differ immensely, this moniker highlights the fungus’s impressive standing relative to its kin. Instead of dominating primeval ecosystems via predation, D. rex embodies an atypical lineage of fungal variety whose evolutionary trajectory could be linked to the ecological shifts following one of the planet’s most severe mass extinction periods.
The findings were published on September 28 in the scientific journal Frontiers in Fungal Biology. Beyond introducing a previously unknown species, the research identifies an entirely new family of fungi and offers clues about how these organisms evolved and adapted to their environments.
A fungus that stands out for its size
One of the most distinctive features of Dianjunus rex is the size of its fruiting bodies, known as stromata. These reproductive structures grow upright and have a fleshy appearance, with elongated projections resembling clustered fingers.
Upon first appearing, the stromata exhibit a pale yellow hue. As the fungus develops, this coloration slowly deepens. Ultimately, these formations can attain a height of roughly 20 inches, an exceptionally large size for specimens within their specific taxonomic classification.
The discovery is particularly significant because D. rex belongs to the phylum Ascomycota, one of the most diverse groups of fungi. This phylum includes organisms as varied as morels, truffles and yeasts, along with thousands of species that are microscopic or rarely observed in the wild.
Before the discovery of D. rex, one of the largest known members of this group was Engleromyces goetzei, a bulky brown fungus found in Kenya. Its fruiting body can reach nearly 12 inches (30 centimeters) in diameter and weigh approximately 7 pounds (3.2 kilograms).
However, D. rex is distinguished by the impressive height of its reproductive structures alongside their unique growth patterns. Numerous closely related fungi barely reach a height of a few inches, whereas others are so diminutive that proper examination demands specialized laboratory instruments.
Stanford University biology and Earth system science professor Kabir Peay underscored the significance of identifying fungi possessing such atypical traits. He pointed out that remarkable specimens enable researchers to grasp the vast diversity of fungal morphologies that remain unrecorded by science.
How the extinction of the dinosaurs may have influenced fungal evolution
The evolutionary origins of Dianjunaceae, the newly identified family that includes Dianjunus rex, are another important aspect of the research. By analyzing genetic material and comparing the fungus with related organisms, scientists estimated that the family emerged approximately one million years after the asteroid impact that brought the Cretaceous Period to an end.
Around 66 million years ago, that catastrophic event triggered a mass extinction that eliminated all non-avian dinosaurs and approximately 75% of Earth’s plant and animal species.
The ecological impact proved immense. Photosynthesis suffered due to diminished sunlight, whereas vast amounts of decaying foliage, timber, roots, and fauna debris piled up throughout impacted habitats. Consequently, these shifts destabilized trophic networks, severely hindering the survival prospects of numerous species.
Yet the surplus of dead organic matter could have additionally generated prospects for decomposers. Fungi are crucial in decomposing dead flora and fauna, recycling nutrients back into the habitat and sustaining the ongoing operation of ecosystems.
Indunil Senanayake, a coauthor of the study and associate professor at the Kunming Institute of Botany in China, explained that these conditions may have benefited certain groups of fungi. Although the precise relationship between the mass extinction and the emergence of Dianjunaceae remains a subject for further investigation, the findings illustrate how major environmental disruptions can influence the evolution and diversification of life.
A local observation led to a scientific discovery
Researchers identified Dianjunus rex during fungal diversity surveys conducted in the forests of Yunnan province in 2024 and 2025. However, local residents had noticed the unusual organism before scientists began investigating it.
Farmers in the area had encountered clusters of fleshy, fingerlike structures growing around a dead tree. Despite its unusual appearance, the fungus had not previously attracted significant scientific attention.
That changed when a local resident shared photographs of the organism with researchers. The images prompted the team to investigate further, examine specimens and conduct genetic analyses to establish the fungus’s identity and evolutionary relationships.
Senanayake reported that some local people had even tasted the fungus without experiencing noticeable adverse effects. However, the researchers have not conducted sufficient toxicity testing to establish whether it is safe to eat. The absence of reported symptoms should therefore not be interpreted as evidence that the species is edible.
The discovery has also raised questions about why D. rex develops such large reproductive structures. Ascomycetes generally do not produce enormous stromata, possibly because building and maintaining them requires considerable energy.
One possibility is that the fungus’s height offers a reproductive advantage. Its upper structures contain thousands of tiny pores through which spores are released. In the forest environments where the species grows, the ground is often covered with fibrous plant material that could interfere with the movement of spores.
By elevating its reproductive structures past the forest floor, D. rex could potentially boost the odds that its spores drift farther and land in favorable spots for germination. Scientists must carry out further investigations to figure out whether this hypothesis explains its atypical dimensions or if different ecological and biological drivers play a role.
Why scientists still have so much to learn about fungi
The identification of Dianjunus rex highlights a significant gap in scientific knowledge. Researchers have formally described approximately 150,000 fungal species, but some estimates suggest that between two million and 13 million species may exist worldwide.
The difference between these figures indicates that a substantial portion of fungal biodiversity remains undocumented. Many species inhabit difficult-to-reach environments, while others are challenging to identify because their visible structures appear only under specific conditions.
The vast majority of any fungus is composed of tiny, thread-shaped filaments known as hyphae. Collectively, they create a web called the mycelium, which generally develops beneath the ground, within rotting timber, or amid plant matter. Those reproductive forms that individuals identify as mushrooms, along with other visible fungal manifestations, merely constitute a fraction of the living entity.
These structures may emerge when environmental conditions are favorable or during particular stages of the fungus’s life cycle. As a result, even a large and distinctive species such as D. rex can remain unnoticed for years.
Stanford’s Peay stressed that documenting fungal species is an essential first step toward understanding their ecological roles. Scientists must first establish which organisms exist before they can investigate how those species interact with plants, animals and their surroundings.
Fungi contribute to the carbon cycle, break down organic matter and support the growth and nutrition of many plants. Understanding their diversity is therefore important not only for taxonomy and evolutionary biology but also for broader research into ecosystem health.
Ultimately, Dianjunus rex represents more than an unusually large fungus. Its discovery provides an opportunity to investigate how fungi evolve, why certain species develop exceptional physical characteristics and how environmental changes shape biodiversity over millions of years. It also serves as a reminder that even in ecosystems that have been explored for decades, nature can still reveal organisms that expand our understanding of life on Earth.
