The planet's greatest death event
Around 251.9 million years ago, Earth experienced its most severe extinction event, known as the Permian-Triassic extinction or "The Great Dying". This global catastrophe eliminated about 96% of all marine species and 70% of terrestrial vertebrate species. The primary trigger is widely considered to be the Siberian Traps, a colossal flood basalt volcanic eruption in present-day Siberia. This event released more than 100,000 billion tonnes of carbon into the atmosphere, triggering extreme environmental changes.
The immediate effects were devastating. Atmospheric carbon dioxide levels surged from around 400 ppm to 2,500 ppm, causing an estimated 8°C (14°F) rise in global temperatures. The massive injection of volcanic gases also produced intense acid rain and depleted the ozone layer. This combination of factors decimated the world's forests, which were primarily composed of conifers related to modern pines. The widespread death of plant life created an unprecedented amount of rotting biomass across the supercontinent of Pangaea, led to a new kind of organism to dominate the planet.
A world consumed by fungi
In the aftermath of the forest collapse, a "fungal spike" appears in the geological record. Palynologists—scientists who study microscopic fossils like pollen and spores—discovered a dramatic increase in fungal remains in sedimentary layers corresponding to the extinction boundary. In some rock samples from this period, nearly 100% of the organic matter consists of fungal microfossils. This evidence points to a world where fungi, feasting on the immense quantities of dead wood, temporarily became a dominant life form.
The fossil evidence is an ichnogenus named Reduviasporonites. Initially debated as either algae or fungi, chemical analysis confirmed its fungal origin. Specifically, studies of its carbon and nitrogen content revealed it to be a type of wood-rotting fungus. Researchers have even noted a strong resemblance between Reduviasporonites and the resting stages of modern fungi in the genus Rhizoctonia. This fungal spike is a marker for the Permian-Triassic boundary in rock formations worldwide, including those in East Greenland. It indicates a global ecosystem collapse so deep that the planet's primary producers were briefly replaced by decomposers on a massive scale.