About 66 million years ago, Earth changed suddenly when an asteroid collided with the planet.
Fires burned out of control. Darkness covered everything.
One by one, the world’s ecosystems began to collapse.
When this massive event took place, almost three-fourths of all species on Earth became extinct.
Many large animals, including dinosaurs, could not survive the disaster as their environments broke down.
However, what’s most surprising is what managed to survive a catastrophe of this scale across such extreme global conditions and rapid environmental collapse.
How were they able to survive such a global disaster?
What went on during a sudden collapse of the world?
Dinosaurs controlled every part of the planet before the asteroid struck.
Predators towered above the rest, while huge herds of plant-eating dinosaurs roamed the earth across vast environments and open landscapes. Compared to them, small mammals were almost invisible.
Everything changed after the collision.
Dust filled the sky, blocking sunlight and spreading across the planet.
Ecosystems collapsed as temperatures dropped and plants began to die off rapidly across different regions.
Many species were unable to survive as food webs collapsed and the basic food sources, they depended on disappeared.
Large animals in these ecosystems struggled to adjust to the loss of food and the changes in their environment. Many could not adapt and eventually died along with their ecosystems.
Smaller organisms faced the same crisis, but a different challenge under rapidly collapsing environmental and food conditions.
They had to adapt quickly as survival conditions became unstable across different environments.
Food sources disappeared, forcing them to adjust their behavior to stay alive.
Some small mammals survived — but why?
As large animals went extinct, smaller mammals remained on Earth.
They did not have advantages like being fast or strong. Instead, they were highly adaptable.
Many were much smaller than earlier species, similar to modern mice or rabbits, and could survive in different environments.
They adjusted their behavior quickly as conditions changed.
These mammals had a flexible diet and could burrow underground to protect themselves when conditions became extreme.
Others moved between areas to find food and avoid danger during harsh conditions.
Those traits made them different from larger animals, but the full reason they survived would only become clear later. This research was reported by the University of Washington.
How do scientists know that answer?
Eventually, scientists discovered why these mammals survived.
Clues to this answer were found along the coast of North America. They came from fossils that revealed new insights into survival.
At first, these fossils appeared ordinary and easy to overlook.
But further research revealed something extraordinary.
What can we learn from surviving catastrophes?
Cimolodon desosai was a mammal about 10 centimeters (4 inches) long.
It likely moved on the ground and in trees, which helped it live in more than one kind of environment.
It ate mostly fruits and insects, which were easier to find during that time. This diet helped it survive when food supplies became limited and harder to predict.
Its size also helped it survive.
Because it was small, it needed far less food during times of scarcity.
It ate a wide range of foods; it could still survive if one source disappeared for long periods. It could also move quickly to escape danger and avoid changing conditions.
Based on fossil evidence, researchers believe this adaptability contributed to the survival of its descendants long after the catastrophe.
Unlike dinosaurs and many large animals that perished in this extinction, mammals were not seen as threats at the time.
Over time, these mammals evolved into new forms of life and eventually shaped life on Earth.