New evidence reveals a more devastating scenario for the extinction of dinosaurs approximately 66 million years ago. An asteroid collision in the Yucatan Peninsula not only ushered in a years-long harsh winter, but also triggered global firestorms of previously underestimated intensity. These extreme blazes could have turned even the largest reptiles to ash within hours, presenting a new perspective on the end of the dinosaur age.
New study redefines the intensity of the catastrophe that hit Earth
For a long time, the predominant explanation for the extinction of dinosaurs was a prolonged “impact winter”, which would have starved these creatures. However, a recent study brings to light a more brutal and immediate understanding of the event. The asteroid, which measured about 10 kilometers in diameter, hit what is now Mexico, creating the gigantic Chicxulub crater and releasing an immense amount of vaporized rock into the atmosphere.
Some of this vaporized material condensed into tiny droplets known as spheres. They spread throughout the planet and, upon returning to the Earth’s atmosphere at very high speeds, their kinetic energy was converted into an intense pulse of thermal radiation. Previous models calculated that this phenomenon would generate considerable global heat, lethal to exposed animals with thin skin, but insufficient to ignite vegetation on a planetary scale.
Layer of fine dust amplified the heat from the asteroid impact
The researchers argue that previous calculations failed to consider a crucial “ingredient”: a thick layer of extremely fine silicate dust. This material formed from rock vapor that did not initially condense into the spheres. Confirmation of the existence of this dust came in 2023, at the Tanis fossil site, in North Dakota, where a layer of very fine impact material was identified above the spheres.
A similar discovery of the dust layer was also recorded at the K-Pg boundary (Cretaceous-Paleogene boundary), which marks the transition from the “age of reptiles” to the “age of mammals”, in the Raton Basin, located on the border between Colorado and New Mexico. “This reignited my interest in what happened to the remaining vapor — it’s where this work began,” said Brandon Johnson, a planetary scientist at Purdue University and lead author of the research.
Heat pulse became 17 times more lethal with dust barrier
The dust acted as a kind of insulating blanket, essential for amplifying heat. Instead of allowing thermal radiation to escape into space, this layer redirected a much larger portion of heat to the planet’s surface. Scientists estimated that the heat pulse at the surface may have been approximately 3.5 times more intense than suggested by models that only considered the falling spheres.
This intensification meant that thermal radiation reached impressive levels of lethality. The study points out that exposed terrestrial animals may have received around 17 times the thermal dose considered fatal to humans. “We’re in the realm where we could be essentially killing everything within the first hour or two,” Johnson detailed, underlining the suddenness and brutality of the event.
The radiation, although not capable of directly igniting dense wood, surpassed the ignition limits for lighter materials. Grass, lichens, and pine needles would have been easily ignited, serving as fuel for fires of gigantic proportions. This suggests immediate and widespread devastation driven by the intense heat, not just the subsequent drop in temperature.
Survival and what remains to be discovered about global fires
Faced with such extreme heat, the animals’ chance of survival depended directly on the refuge. Those that were sheltered underground or submerged in water would have been more likely to withstand the initial pulse of heat. Interestingly, the same layer of dust that intensified the heat is said to be responsible for blocking sunlight for years after the impact, triggering the “impact winter” that followed.
- The Chicxulub asteroid impact occurred 66 million years ago.
- The layer of fine silicate dust amplified the heat pulse at the Earth’s surface.
- The resulting heat may have been 17 times the lethal thermal dose for humans.
- Fires were fueled by light vegetation such as grass and lichens.
- Animals protected in underground or aquatic environments had a greater chance of survival.
One unknown element remains in this new theory: Most of the wildfire evidence supporting the dust-induced inferno hypothesis has been found only in North America. “We may eventually find a record of completely global forest fires,” commented Alfio Alessandro Chiarenza, a paleontologist at University College London who was not involved in the study, highlighting the need for more research.