Asteroid dust may have intensified the lethal heat that killed the dinosaurs

Fine dust thrown into the atmosphere after the asteroid impact 66 million years ago may have significantly amplified the thermal pulse and been one of the key factors in the extinction of non-avian dinosaurs. This is the conclusion reached by researchers from Purdue University. The work is published in the Journal of Geophysical Research: Biogeosciences.

What Happened After the Impact

An asteroid about 13 kilometres in diameter struck the area of the modern Yucatán Peninsula at a speed of roughly 72,000 kilometres per hour. The impact ejected a vast amount of molten rock into the atmosphere. Part of this material quickly condensed into tiny particles the size of a grain of salt. These spread across the planet and, over the course of several hours, began to fall back to the surface.

However, a significant portion of the material turned into even finer dust. According to the scientists' estimates, about 1.8 trillion tonnes of such particles may have formed. It was this dust that played a particular role.

How the Dust Intensified the Heat

The fine particles were almost opaque to infrared radiation. The heat from the scorching debris falling back to Earth was trapped near the surface instead of escaping into space.

"It is surprising how effectively this dust prevents radiation from leaking into space," noted researcher Alexandria Johnson.

As a result, the thermal pulse was considerably more intense than earlier models predicted, which had not accounted for the effect of such fine dust. Calculations show that exposed surfaces could have heated to lethal levels. Under such conditions, delicate vegetation, pine needles, and lichens could have ignited in under a minute.

In these circumstances, animals that could quickly take cover from the heat—by burrowing into the ground, hiding in caves or mud, or retreating underwater—had a higher chance of survival.

What the Geological Evidence Shows

Traces of the catastrophe have been preserved in rock layers. At the Tanis site in North Dakota, fish that died on the day of the impact were buried together with particles of molten rock. Above them lies a layer rich in iridium—a typical indicator of asteroid material.

How Reliable Are the Conclusions

The authors emphasise that the study does not yet prove that the thermal pulse was the primary cause of the extinction. The conclusions are based on computer modelling and dust composition data obtained by other research groups. Ahead lie verification of the calculations using samples from different regions and experiments to show how such a thermal pulse affects real forest ecosystems.

In Brief

Researchers from Purdue University have shown that fine dust generated after the asteroid impact 66 million years ago may have greatly intensified the thermal pulse at the Earth's surface. About 1.8 trillion tonnes of such particles trapped infrared radiation, making the heat lethal for exposed organisms. Animals capable of quickly taking shelter had a better chance of survival. For now, this remains one hypothesis that still requires further testing.

Follow NEWS.am Tech on Facebook and Twitter