Giant megafungi called Prototaxites, the “Godzilla of fungus,” essentially terraformed Earth 420 to 350 million years ago. While other lifeforms were diminutive, the megafungi stood like strange towering spires in the landscape. Only invertebrates like millipedes and worms had made their way to land.
These giants made life on the planet possible and are “closer cousins to animals” than plants. As they mined rocks for nourishment, the fungus slowly created what would become fertile soil. Thus, they helped create the environment in which plants would turn Earth green and change our atmosphere.
Long ago, some of the earliest plants, liverworts, lived in symbiosis with the megafungi. At first, some scientists believed Prototaxites were actually giant mats of liverworts. However, other scientists would find evidence they were more closely related to animals.
Today, there remains debate about what Prototaxites were. Some say the megafungi may have had some ability to photosynthesize light similar to a lichen.
26-Foot Tall Giant Megafungi Stood Like Towers
Prototaxites were possibly megafungi standing eight meters or over 26 feet tall. Originally, scientists thought fossils of these giant fungi were conifer trees. After 100 years, scientists debated what these fossils were: lichens, trees, marine algae, fungi, or plants.
Then, in 2007, scientists verified they were a giant fungus. Rather than absorbing all their carbon dioxide from the air like plants, the megafungi chemically absorbed some of it from other sources.
At the time, Kevin Boyce, a geophysicist at the University of Chicago in Illinois, remarked that Protoxites was “one of the weirdest organisms that ever lived.”
“No matter what argument you put forth, people say it’s crazy,” said Boyce, a geophysicist at the University of Chicago in Illinois, US. “A 6-metre-fungus doesn’t make any sense, but here’s the fossil.”
Towering Megafungi Terraformed Earth
For millions of years, the obelisk-like Prototaxites were helping terraform the planet. Like chemists, fungi create molecules that scientists are unable to create in a lab.
As fungi decompose decaying matter, they act like garbage disposals. By breaking down organic matter with digestive enzymes, they release nutrients, making them available for plants.
Lynne Boddy, a biosciences professor at Cardiff University, explained how fungi’s activities change the entire web of life.
“[Fungi] are the garbage disposal agents of the natural world,” said Boddy. “They break down dead, organic matter and by doing that they release nutrients and those nutrients are then made available for plants to carry on growing.”
“It’s how everything is reborn,” Dunn said. “So that this entire web of life is connected and it’s connected through the fungi.”
Today, scientists are only beginning to understand how fungal highways connect life in forests. Mycorrhizal fungal networks create elaborate communication systems underground, allowing trees to communicate and share nutrients. Fungal threads called hyphae merge with the tree roots, living in symbiosis.
In the late 1990s, Francis M. Hueber, a palaeobotanist at the National Museum of Natural History in Washington, saw hyphae-like structures in fossils from Prototaxites. This anatomical evidence confirmed his long-held belief the fossils represented a fungus after decades of study.
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Did Megafungi Give Mammals an Advantage?
About 65 million years ago, an asteroid impact deprived the planet of sunlight. As lifeforms died and decayed, fungi spread even further.
As a result, the megafungi may have created conditions favoring the rise of mammals. Whereas reptiles are susceptible to fungal pathogens, mammals could fight them off with their warm blood.
Rob Dunn, a professor at North Carolina State University, stated:
“The warm-bloodedness of mammals, including ourselves, has evolved, in part, as a response to the pressure from fungus,” said Dunn. “And so we seem to have cooked out the fungal pathogens.”
On the other hand, scientists are learning some dinosaurs may not have been coldblooded like today’s reptiles. Instead, they may have been endotherms, creating their own body heat.
The Demise of Prototaxites
Eventually, the animals that evolved on Earth thanks to the fungi may have consumed Prototaxites. Dr. Francis Hueber of the Smithsonian believes that insects began eating the megafungi, leading to their extinction. It’s almost as if their purpose was terraforming Earth. Once accomplished, they faded away.
Nevertheless, today the largest living organism on the planet remains a huge fungal mat 3.5 miles across in the Malheur National Forest in eastern Oregon.
There, the fungus called the “honey mushroom” spreads through the tree roots over 2,200 acres. For 2,400 years, the Armillaria has sent out black shoestring filaments called rhizomorphs that can kill trees.
Below ground, the rhizomorphs stretch 10 feet into the ground. However, all one sees aboveground are clumps of golden mushrooms.
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