Sixty-six million years ago, a vast asteroid struck the Earth and bent the course of life in ways that still shape the land we walk on today. In the wet, warm lowlands of what is now Colombia, a forest of conifers and ferns with widely spaced trees gave way in the wake of that catastrophe to something new. An international team, reading tens of thousands of leaf and pollen fossils published in Science, suggests that the great dying opened a door, and that the rainforests we know now grew through it.
Asteroid That Killed the Dinosaurs May Also Have Shaped Modern Tropical Rainforests
Their loss was flowers' gain
Mark
So the headline is that the asteroid helped create modern rainforests. What did the researchers actually look at?
Mimi
Tens of thousands of fossils, mostly leaves and pollen, from the region that is now Colombia. They compared plant life before and after the impact.
Mark
And what was the forest like before?
Mimi
Wet and warm, but full of conifers and ferns. The trees were widely spaced, so big patches of light got through.
Mark
That's a very different picture from a dense rainforest.
Mimi
Yes. The study describes it as two different forests, separated by the extinction event.
Luke
I want to be careful about the wording, though. The reporting says the crash was "probably" responsible for the modern makeup. That's a strong inference, not a proven cause.
Mark
Fair. What is solid, then?
Luke
The fossils exist, and they show a before and an after. The 75 per cent figure for land-based extinctions is described as "as much as," so it's an upper estimate.
Mimi
And the heat, tidal waves and clouded sky are described as what the impact is "thought" to have caused.
Luke
Right. Also, this excerpt covers one region. It doesn't tell us whether other rainforests followed the same path, and it doesn't detail how flowering plants took over.
Mark
So the Colombian record is the evidence, and the wider claim is still an interpretation.
Il Polso
- A single asteroid strike sixty-six million years ago drove as much as 75 per cent of land-based life to extinction.
- Researchers pored over tens of thousands of fossils from Colombia, searching the rock for proof of what the crash erased.
- Leaf and pollen records reveal two sharply different forests, one before the impact and one after, with the old world thinning out.
- The loss of the old plant community cleared space for flowering plants, and the modern tropical rainforest took root in that opening.
Sixty-six million years ago, a vast asteroid struck the Earth and bent the course of life in ways that still shape the land we walk on today. In the wet, warm lowlands of what is now Colombia, a forest of conifers and ferns with widely spaced trees gave way in the wake of that catastrophe to something new. An international team, reading tens of thousands of leaf and pollen fossils published in Science, suggests that the great dying opened a door, and that the rainforests we know now grew through it.
Sixty-six million years ago, a huge asteroid struck Earth and changed the course of life on the planet. For the dinosaurs it was a catastrophe. A new study in the journal Science suggests that in the tropical rainforest, the same event opened the way for flowering plants.
An international team built the study on tens of thousands of fossils from the region now known as Colombia. By following plant life before and after the impact, they concluded that the crash was probably responsible for the modern makeup of tropical rainforests.
The impact released enormous heat, set off tidal waves and darkened the sky. As much as 75 per cent of land-based life went extinct, a measure of the scale the researchers were trying to read in the rock.
Before the extinction, the forest was wet and warm but unlike today's. Conifers and ferns filled it, and widely spaced trees let light reach the ground. The loss of those older communities made room for flowering plants, and the rainforest we now know took shape in the aftermath. The findings add to evidence that mass extinctions reshape ecosystems by changing which species come to dominate, and they point to Colombia's fossil record as a place to keep searching.
Sixty-six million years ago, a huge asteroid struck Earth and changed the course of life on the planet. For the dinosaurs it was a catastrophe. A new study in the journal Science suggests that in the tropical rainforest, the same event opened the way for flowering plants.
An international team of researchers built the study on tens of thousands of fossils. They used them to follow what happened to plant life in the region that is now Colombia, before and after the impact. Their conclusion is that the crash was probably responsible for the modern makeup of tropical rainforests.
The impact itself is thought to have released enormous heat, set off tidal waves and shrouded the sky in cloud. In its aftermath, as much as 75 per cent of land-based life went extinct. That figure frames the scale of what the researchers were trying to read in the rock.
To reconstruct the landscape before the extinction, the team studied fossilized leaves and pollen from the region. Together, the two kinds of evidence describe two different forests, one before the impact and one after.
The forest before the crash was wet and warm, much as a tropical region might be expected to be. But it was not the forest of today. It teemed with conifers and ferns, and its trees were widely spaced, which let large patches of light reach the ground.
The extinctions that followed the impact changed that arrangement. According to the study, the loss of life opened the door for flowering plants, and the modern tropical rainforest took shape in the aftermath.
The findings add to evidence about how mass extinctions remake ecosystems, not only by removing species but by changing which ones come to dominate. The work points to the Colombian fossil record as a place to keep looking for how today's rainforests came to be.
Citazioni salienti
The crash was probably responsible for the modern makeup of tropical rainforests.— Findings of the international research team, published in Science
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