Why didn’t the asteroid that caused the extinction of the dinosaurs on Earth also lead to the extinction of all other living species?
In: Planetary Science
It did, it wasn’t just dinosaurs more than 95% of species disappeared, the impact itself wasn’t the worst part, the entire world was engulfed in a cloud of ash and dust for a long time so there was no sun for plants and without plants herbivores die and without herbivores predators die only a few lucky ones survived and reproduced and evolved into all the species we have now.
Because life, uh, finds a way.
Earth is no stranger to mass extinction events, and life has always recovered. So it’s no surprise that something would have survived the end of the Cretaceous. In the case of the dinosaurs, it was likely a combination of lack of food and shelter.
Dinosaurs were warm blooded, and dinosaurs of the Cretaceous tended to be larger than their Triassic and Jurassic ancestors. Being large and warm blooded means you need a metric ton of food to survive. Smaller avian dinosaurs (birds) and larger cold blooded reptiles such as crocodiles had an easier time dealing with a food shortage simply because their food requirements were lower.
Being small was also an advantage for mammals. Our tiny ancestors could burrow or hide in natural shelters such as caves or trees. Fur, as with feathers, is also a great insulator, so keeping warm during a time of low sunlight was less of an issue.
Life is nothing if not adaptable. Even with catastrophic events such as an asteroid impact or anthropogenic climate change, something survives. Dinosaurs dominated the landscape for almost 200 million years. Then the world changed around them. Small fluffy things could deal with the change. Tyrannosaurus could not.
There is a recent speculation that this on may have been the result of two different asteroid strikes. The more famous One that occurred in now modern day Mexico but there’s another sizable one in the Antarctic. Because it’s covered with kilometers of ice we can’t study it real close but we’ve studied it close enough to know that it happened at about the same time geologically speaking
The asteroid threw a lot of debris into the atmosphere/orbit which blocked the sun for a time and fell back as mini asteroids that heated up the atmosphere making the surface feel like an oven for a brief period of time. Animals that buried or happened to be under water when the earth became an oven survived.
After this stage, the lack of sunlight decreased the land vegetation for a few years. All land animals that only eat leaves died including most of the dinosaurs. Any carnivore dinosaur that ate these large herbivores also went extinct.
The animals that survived included smaller animals that didn’t need a lot of food, eats a variety of food including nuts and meat (omnivore), and buried or lived at least partly under water. This includes all mammal groups, of which three are still alive (placental, marsupials and monotremes) and three bird groups as well which are smaller dinosaurs.
Mammals had the advantage of being burrowers, omnivore diet and small. Birds had an advantage of being small, omnivore, and flying to find their food. Pterosaurs that tended to be larger than birds due to comparison with birds, all went extinct. A lot of reptiles survived because they were able to stay under water and cold blooded helped because they don’t need a lot of food.
When the asteroid hit it super heated the atmosphere for a short period of time. That caused everything above ground to die.
As it turns out earth is an excellent insulator. So anything that could burrow at least a few feet into the soil survived.
That included some ancient mole. That mole is the common ancestor of all mammals including humans (I’m not kidding).
it killed almost all life but a very small percentage of life survived. And then over a very long period of time, because of evolution and mutation, that tiny percentage of life spread out and became the huge diversity of life that currently exists.
There is basically nothing that can kill ALL life, if even one single-celled organism survives, life will evolve again into a vast ecosystem, eventually.
It wiped out almost every living thing on this planet.
That being said life life finds a way.
What was left behind were the “strongest” and most adaptable creatures
Something to add, is that there were a lot of big dead animals and plants – detritus. I’ve read some papers that argue that the bacteria and fungi we have today that eats detritus wasn’t as common back then therefore plenty of potential food not rotting. There was plenty of food for smaller animals to go around for a while.
This Radiolab episode explains it very well and simply enough for eli5.
Big rock hit.
Big rock go *BOOM*!!!
Big boom kill. A lot. Not so much food anymore.
Big things need big food. But big rock kill big food.
Only little food left. So only little things live.
And the big things…all die. Make big meal for little things.
TLDR: Asteroid didn’t kill everything, only lowered the total amount of food available. Anything that couldn’t live on the new lower total died. Everything else survived, more or less.
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