Dinosaurs ended the reign of the land 65 million years ago, when an asteroid, the size of Mount Everest, crashed into the Earth. Now, it appears that massive impact also remade plant life over the entire planet.
When the asteroid struck the Earth in the Yucatan Peninsula near Chicxulub, Mexico, it exploded with the force of 100,000 megatons of TNT. This threw massive quantities of dust and other particles into the air, blocking out the Sun and radically changing the environment on our home planet. The event also caused fires around the world and led to volcanic eruptions.
University of Arizona researchers studied the event, and determined that evergreen plants were affected by the catastrophe to a greater extent than their deciduous cousins. The impact wiped out more than half of plant species living at the time. Deciduous plants may have been better-able to adapt to a rapidly-changing environment than evergreens, according to the study.
Angiosperm fossils, created from non-coniferous flowering plants, were examined in an effort to determine how this variety of plants responded to the ancient impact. These artifacts were formed over a period of 2.2 million years, stretching from 1.4 million years before the cataclysmic event to 800,000 years after the impact.
Deciduous angiosperms grow quickly, and the study found that these species quickly dominated evergreens following the collision. This could have been brought about by extreme climatic variations that were present on Earth following the event.
Researchers studied the mass of leaves compared to their size, as well as the density of veins in the fossils to determine how the asteroid impact affected their survival.
"We measured the mass of a given leaf in relation to its area, which tells us whether the leaf was a chunky, expensive one to make for the plant, or whether it was a more flimsy, cheap one. In other words, how much carbon the plant had invested in the leaf," Benjamin Blonder, lead author of the study, said.
Evergreen angiosperms in the modern day, including ivy and holly, grow more slowly than other varieties, potentially explaining the lack of resilience for the plants. This difference could have an impact, even in our modern age.
"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... a dramatic shift from slow-growing plants to fast-growing species... tells us that the extinction was not random... [a]nd potentially this also tells us why we find that modern forests are generally deciduous and not evergreen," Blonder said.
Study of the asteroid impact that ended the age of dinosaurs, and how it affected plant life on Earth was published in the online journal Plos Biology.
