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 found in the forests of Yunnan province in southwestern China is attracting scientific attention because of its extraordinary size and evolutionary history. Named Dianjunus rex, the species produces upright reproductive structures that can reach approximately 20 inches (50 centimeters) in height and weigh nearly 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.
On September 28, the results appeared in the academic journal Frontiers in Fungal Biology. Aside from presenting a previously undocumented species, the study uncovers a brand-new family of fungi, providing insights into the evolutionary paths and environmental adaptations of these organisms.
A fungus that stands out for its size
One of the most striking characteristics of Dianjunus rex involves the dimensions of its fruiting bodies, which are referred to as stromata. Rising vertically, these reproductive organs display a fleshy texture alongside extended projections that bear a striking resemblance to grouped fingers.
When they first emerge, the stromata are pale yellow. Their color gradually darkens as the fungus matures. At their largest, these structures can reach approximately 20 inches in height, making them unusually large for members of their taxonomic group.
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.
Approximately 66 million years ago, that cataclysmic event sparked a mass extinction capable of wiping out all non-avian dinosaurs alongside roughly 75% of the planet’s flora and fauna.
The environmental consequences were profound. Reduced sunlight disrupted photosynthesis, while large quantities of dead leaves, wood, roots and animal remains accumulated across affected ecosystems. These changes disrupted food webs and made survival difficult for many organisms.
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.
Everything shifted once a community member posted pictures of the creature online. Those photos motivated the experts to dig deeper, inspect physical samples, and run genetic tests to determine the exact species and its phylogenetic connections.
Senanayake noted that a few residents had actually consumed the mushroom without suffering any apparent ill effects. Still, the investigators have failed to perform adequate toxicity assessments to determine its safety for consumption. Consequently, the lack of documented symptoms ought not to be viewed as proof that the organism is fit to eat.
This finding has additionally sparked inquiries concerning the reasons behind the substantial growth of reproductive organs in D. rex. Typically, ascomycetes refrain from generating massive stromata, a tendency likely linked to the substantial metabolic cost required for their construction and upkeep.
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 gap between these numbers demonstrates that a significant share of fungal biodiversity is still unrecorded. Numerous species dwell within hard-to-access habitats, whereas others prove difficult to recognize since their visible structures emerge exclusively under precise circumstances.
Most of a fungus consists of microscopic, threadlike filaments called hyphae. Together, these form a network known as the mycelium, which typically grows inside soil, decaying wood or vegetation. The reproductive structures that people recognize as mushrooms or other visible fungal growths represent only part of the organism.
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 emphasized that cataloging fungal varieties serves as a crucial initial phase in grasping their ecological functions. Researchers first need to determine which organisms are present prior to exploring the ways those species engage with flora, fauna, and their environment.
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 stands for far more than just a remarkably massive fungus. Its discovery offers a chance to explore fungal evolution, understand why specific species grow extraordinary physical traits, and see how shifts in the environment mold biodiversity across millions of years. Furthermore, it acts as a gentle reminder that, even within environments studied for decades, nature retains the capacity to unveil organisms that broaden our comprehension of existence on Earth.