The meteorite that killed the dinosaurs gave birth to the Amazon rainforest.
About 66 million years ago, a huge asteroid hit the earth and wiped out the dinosaurs. In addition, it is the origin of the Amazon, the largest tropical forest in the world.
At the end of the Cretaceous, there was an asteroid 10 kilometers wide Crash Deal with the earth near the small town of Chicxulub, Mexico.
The impact of meteorites released an incredible amount of gas, which changed the climate, triggering the extinction of non-avian dinosaurs and the extinction of 75% of life on Earth.
However, among the abnormal butterfly effects, the extinction of dinosaurs and the way climate change affects forests are the origin of the earth’s green lungs, the Amazon rain forest as we know it today.
Advantages of flowering plants
In the analysis of thousands of fossil pollen and leaf samples before and after the Chicxulub impact, Smithsonian Tropical Research Institute We found that the catastrophe also led to the extinction of 45% of the plants in Colombia, which laid the foundation for the development of the tropical rain forest as we know it.
If asteroids did not change the world, Amazon would not be like Amazon.
Before the asteroid hit what is now Mexico’s Yucatan Peninsula, the rainforests of South America consisted of vegetation that was very different from today. It has nothing to do with the large number of flowering plants that attract the Amazon jungle today.
Carlos Jaramillo of the Smithsonian Tropical Research Institute in Panama said: “If we go back to the day before the meteorite fell, now the forests of the Amazon River will be full of ferns, many conifers and dinosaurs.” “Today’s forest is the product of events that occurred 66 million years ago.”
Jaramillo and his colleagues analyzed thousands of fossil pollen and leaf samples found in northern South America, which date back to the Cretaceous period. Asteroid impact And it happened in the Paleocene era.
They found that the diversity of plants dropped by 45% after being affected, and it took 6 million years to recover. The traces of insects on fossil leaves indicate that their diversity has also declined.
After the impact, the conifers almost completely disappeared from the tropical regions of the New World, and the flowering plants spread into the tropical rain forest.
After the disaster, the rainforest in South America has changed. Coniferous trees are common and cast shadows on dinosaur tracks. After the impact, the conifers almost completely disappeared from the tropical regions of the New World, and flowering plants spread into the jungle.
Most cones and ferns have disappeared, and the rainforest is dominated by flowering plants called angiosperms.
The researchers found evidence that the distance between tropical trees before the impact was wide enough to allow light to reach the bottom of the forest.
Compared with the water that grows millions of years later, the canopy of the forest before the impact is much more scattered, there are fewer flowering plants, and the amount of water they transport from the ground to the atmosphere will be reduced.
Dr. Carvalho explained: “It was the same rainy day in the Cretaceous, but the way the forest worked was different.”
The impact of the meteorite turned the rare coniferous tropical forest of the dinosaur era into the tropical forest of today: the towering trees are decorated with yellow, purple and pink flowers and are dotted with orchids.
Dr. Carvalho and his colleagues proposed three explanations for this change:
One idea is that the dinosaurs kept the forest open before the impact by eating and moving throughout the landscape.Meteor impact wiped out Large herbivorous dinosaur , Which prevents them from trampling and eating low-level forests. Therefore, when the dinosaurs disappeared, the forest was closed.
The second explanation is that the ash from the impact enriches the soil in the tropics and provides advantages for faster-growing flowering plants. The ashes that settled in the sky after the impact may have been used as fertilizer, forming a nutrient-rich soil that prefers fast-growing angiosperms to other plants.