SCIENCE LAB SCREAMS : DINOSAURS DUST

 

Particles Of Doom : For Dinosaurs - a bad case of dust to dust. On a spring day over 86 millions years ago, an asteroid slammed into the sea just off the coast what is now Mexico. Known as the Chicxulub impact, it set off a global shock wave, earthquakes and mega tsunamis that exterminated nonavian dinosaur and plunged Earth into a long and dark winter.

A study published in the Journal Nature Geoscience has uncovered the cause of this cold snap : dust.

The study's authors say that minute grains of silicate dust lingered in the atmosphere as long as 15 years after the impact and contributed to the global cooling.

All photosynthetic activity on Earth may have ceased within two weeks after the Chicxulub impact, largely because of the fine dust, they said.

Stephen Brusatte, a paleontologist at the University of Edinburgh who was not involved in research, said studies like this one aided understanding of the period after the asteroid's impact.

'' They help us empathize with T.rex, Triceratops and the other dinosaurs that woke up in the morning on top of the food chain but by the end of the day were facing a world of chaos,'' he said.

During fieldwork in 2017, Pim Kaskes a geologist in Belgium and an author of the new research, collected some fine-grained samples from a geological formation in North Dakota known as Tanis, which yielded a trove of fossils.

While Texas is 2,000 miles [ 3,200 kilometers ] from the site of the impact; seismic waves created a deposit of minerals known as the Cretaceous-Paleogene boundary.

Dr. Kaskes shared the samples with Cem Berk Senel, a paleoclimate model researcher at the Royal Observatory of Belgium who was then a graduate student at Universite Libre de Bruxelles.

'' One of the key questions we wondered was what was the primary governor of Chicxulub mass extinction event because, in the literature, there have been diverse hypotheses, addressing the phenomenon,'' Dr. Senel said.

The role of dust has often been overlooked in the extinction event. Scientists have focused instead on sulfur particles that rocks released after the asteroid vaporised them, as well as soot from the impact and subsequent wildfires.

'' The effects of the dust were not well known,'' Dr. Kaskes said. '' Most of the work that has been done used very coarse-grained material that rains very rapidly out of the atmosphere of extremely fine particles that also rain down relatively quickly.'' [ Miriam Fauzia ]