Meteorite that killed dinosaurs helped forests bloom, Study

The killer meteorite that extinguished the dinosaurs also torched North America’s forests and plants. The harsh conditions after the impact favored fast-growing flowering plants, nudging forests toward a new pecking order, a new study reports.

Around 66m years ago, a 10km-wide asteroid or comet smashed into the Earth off Mexico’s Yucatan peninsular, producing a crater 150km across.

Three quarters of all plants and animals — including the dinosaurs — became extinct after the event which triggered mega-tsunami, wildfires, earthquakes, and an “impact winter”.

But new research suggests the cataclysm proved a turning point for the deciduous plants that now dominate vegetation on Earth.

After the impact, fast-growing deciduous species rapidly began to take over from the previously ubiquitous evergreens.

Lead scientist Dr Benjamin Blonder, from the University of Arizona, said: “If you think about a mass extinction caused by catastrophic event such as a meteorite impacting Earth, you might imagine all species are equally likely to die.

“Survival of the fittest doesn’t apply — the impact is like a reset button. The alternative hypothesis, however, is that some species had properties that enabled them to survive.

“Our study provides evidence of a dramatic shift from slow-growing plants to fast-growing species. This tells us that the extinction was not random, and the way in which a plant acquires resources predicts how it can respond to a major disturbance.

“And potentially this also tells us why we find that modern forests are generally deciduous and not evergreen.”

Deciduous plants, which grow fast and lose their leaves at some point during the year, were better able to survive the changing conditions of an impact winter.

Evergreen plants, such as holly, tend to have leaves that are costly to construct but robust and long-lasting. Leaves of deciduous plants are short-lived and more cheaply built, but easier to replace.

Agencies/Canadajournal