Following the extinction of the dinosaurs roughly 66 million years ago, alternative biological organisms adjusted to an evolving globe. A massive mushroom recently discovered in China is providing researchers with fresh perspectives regarding fungal development and the extraordinary biodiversity that still remains unmapped.
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 comparison with Tyrannosaurus rex, the famous dinosaur often described as the king of prehistoric predators. Although the two organisms are vastly different, the name reflects the fungus’s remarkable stature among its relatives. Rather than ruling ancient ecosystems through predation, D. rex represents an unusual branch of fungal diversity whose evolutionary history may be connected to the environmental changes that followed one of Earth’s largest mass extinction events.
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 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.
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 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 abundance of dead organic material may also have created opportunities for decomposers. Fungi play a central role in breaking down dead plants and animals, returning nutrients to the environment and supporting the continued functioning of ecosystems.
Indunil Senanayake, an associate professor at the Kunming Institute of Botany in China who also coauthored the research, pointed out that such settings could have favored specific fungal lineages. Even though the exact connection linking the mass extinction event to the rise of Dianjunaceae calls for additional study, the discovery demonstrates how significant ecological crises are capable of shaping the evolutionary trajectory and proliferation 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.
Local farmers had come across groups of fleshy, finger-shaped growths developing near a deceased tree. Even though its peculiar look was undeniable, the fungus had not previously drawn much academic interest.
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 raising its reproductive structures above the forest floor, D. rex may increase the likelihood that its spores travel farther and reach suitable locations for growth. Researchers will need to conduct additional studies to determine whether this explanation accounts for its unusual size or whether other biological and environmental factors are involved.
Why researchers still have so much to discover regarding fungi
The recognition of Dianjunus rex underscores a notable blind spot within scientific understanding. While experts have officially cataloged roughly 150,000 types of fungi, certain projections indicate that a staggering two million to 13 million distinct varieties could actually populate the globe.
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.
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 formations can develop when environmental conditions prove favorable or throughout specific phases of the fungal life cycle. Consequently, a substantial and conspicuous species like D. rex may easily elude detection 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 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.