66 million years ago, the meteorite that killed off the dinosaurs also decimated the Earth’s forests. The impact helped kill off the slow-growing evergreens. According to a new study, published in PLOS Biology, the harsh conditions that followed the impact benefitted fast-growing flowering plants.

If you decided to pull a Jurassic Park and bring back the dinosaurs without their native plants, it would be a complete reversal of what the animals saw and ate 66 million years ago. In a sense, the forest’s natural order was reversed. The trees and shrubs that some dinosaurs ate then are now on the low-end of the pecking order.

Lead author, Benjamin Blonder released a statement on his work. “When you look at forests around the world today, you don’t see many forests dominated by evergreen flowering plants. Instead, they are dominated by deciduous species, plants that lose their leaves at some point during the year.”

In the time of the dinosaurs, forests were dominated by evergreen angiosperms. These plants never dropped leaves and were the ancient relatives of holly, rhododendrons and sandalwood. Go out into any wooded area today. How many rhododendrons do you stumble across?

Before the meteorite slammed into Earth, the landscape was dotted with angiosperms of all type. The impact had the effect of charring vast forests from what is today New Mexico to Canada. Fossil records show that 60% of North American plant life went extinct.

According to the research, it was the impact winter that led to the rise of deciduous trees. Plants had to quickly adapt to fast-growing strategies, including dropping leaves. In this period, leaves represented a drain on a plant’s resources. The plants didn’t exactly have a long growing window, so deciduous species quickly became dominant over evergreen species.

Analyzing leaf mass per area showed the research team how much carbon a plant invested in growing a leaf. “This tells us whether the leaf was a chunky, expensive one to make for the plant, or whether it was a more flimsy, cheap one,” Blonder said.

The takeaway of the research is that it showed the extinctions that occurred from the meteor impact was not random. Also, it answers why modern forests are made up of primarily deciduous trees versus evergreens. It was the forest’s version of survival of the fittest.

Read the full study here.

IMG Credit: Michael Schweppe (Wikipedia)

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