TUCSON, Sept. 16 (UPI) -- Millions of years ago, a giant meteorite struck the Yucatan peninsula, sending up a dust cloud that encircled the Earth and choked out the many dinosaur species that dominated the planet's food chains. That same impact that extinguished the dinosaurs changed the makeup of Earth's forests -- killing off many evergreen plant varieties and enabling the proliferation of deciduous shrubs and trees.
After studying thousands of fossilized leaves -- specimens sourced from North Dakota's Hell Creek Formation and originating from a 2-million-year interval of geologic time that spanned the extinction of the dinosaurs and the transition from the Cretaceous period to the Paleogene -- researchers at the University of Arizona found that fast-growing deciduous plants quickly supplanted slow-growing evergreen species in the wake of the cataclysmic impact that killed off T. rex.
"When you look at forests around the world today, you don't see many forests dominated by evergreen flowering plants," explained the study's lead author Benjamin Blonder, an evolutionary biologist at Arizona. "Instead, they are dominated by deciduous species, plants that lose their leaves at some point during the year."
Blonder and his colleagues surmise that deciduous plants acquire resources in a way that enabled them to more quickly adapt to quickly-changing post-apocalyptic circumstances. Clearly, the aggressive nature of fast-growing deciduous plants proved advantageous in an unpredictable environment.
"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," said Blonder. "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."
The work of Blonder and his fellow researchers was published this week in the journal PLoS Biology. Blonder's efforts were funded by the National Science Foundation and the Geological Society of America.