How did animals survive the asteroid?

Today there are over 10,000 species of birds on Earth, many of which have descended from their ancestors that were alive at the same time as the dinosaurs. There are also many other creatures like reptiles and small mammals that have evolved from things that were on the planet when the dinosaur-killing asteroid hit. So how did they all survive when the dinosaurs didn’t?

What exactly was the Asteroid?

Around 65 million years ago, a giant piece of rock that was between 10 and 15 km wide smashed into the earth at a site in modern-day Mexico. The crater at the site of impact is known as the Chicxulub crater and is located on the Yucatán Peninsula in Mexico. The force with which it hit caused global catastrophes such as tidal waves, earthquakes, and triggered many volcanoes around the planet. The combination of the impact and all the other problems it caused threw a thick layer of smoke and ash into the atmosphere, which devastated plant life and caused acid rain to poison many water sources and further damage vegetation around the world.

(The site of the impact crater in modern-day Mexico)

Which animals actually survived?

Most species of birds today can trace their ancestors back to those that existed well before the dinosaurs died. Many reptile species such as crocodiles, turtles, and snakes are all thought to have evolved from pre-asteroid animals. But after birds, the shark is probably the most well-known creature, with the earliest version being dated back to at least 420 million years.

(Many of the larger bird-like dinosaurs couldn’t fly, at least not for long enough distances to escape)

How did some animals survive the asteroid when the dinosaurs didn’t?

The most widely agreed-upon answer would be the animals that survived did so because they had the ability to hide from the atmospheric conditions. Birds are highly resistant to the cold and can move quickly across land that may be flooded or impassable for a land animal. Many of the species that were around at the same time as the dinosaurs were much larger than today’s birds, and would be able to fly for hundreds of miles. Even today the tiny sparrow can fly thousands of miles in its life, and a seagull can cover over 100 miles in one day. This would let them reach areas of the earth that were calmer during the years of intense weather and natural disasters, something larger land-dwelling dinosaurs couldn’t do.

Reptiles and sharks could hide from disasters when they happened, either underwater or in their burrows or small hiding spots. Snakes would be able to find the smallest gaps deep within piles of rocks and escape the incoming storm, which was similar for lizards and amphibious reptiles. Mammals on the other hand only just made it through, and the majority of species were wiped out.

(The Deinosuchus, an ancestor of the crocodile lived between 82 to 73 million years ago)

Small rodent-like animals could hide better than giant dinosaurs but still relied heavily on local plants for food. This was a problem in areas that were covered by thick layers of ash or had the sun blocked out for long enough for everything to die. When the asteroid hit, the initial impact wiped out pretty much everything in Central America, but most of Europe, Africa, and Asia weren’t affected by an immediate death wave, such as a shockwave strong enough to kill them.

Most of the dinosaurs died out over the following decades due to starvation, exposure to extreme conditions, or being in the firing line of a natural disaster like a tidal wave or violent super-storm. The short answer would be that anything that could fly vast distances was able to effectively hide from the disasters and had a chance of making it through, but even with all the species that survived, the majority of them were wiped out.

Could humans survive another asteroid?

No, no we couldn’t, or at least nothing like we are now. Presuming it hit the earth, the human race would drop to less than 1% of what it is now within a few months. Law and order would break down as people fought for any remaining food, knowing that no more could be grown for quite some time while the ash and dust blocked out the sun for years. Disasters, both natural and man-made would devastate huge parts of the earth, and all those nuclear power stations and missiles could be ripped apart by mega storms and earthquakes.

Food would disappear and so would the chance to grow more, possibly for decades. Infrastructure would crumble and power stations wouldn’t be able to work, with everyone out for themselves, looking for very limited food or medicine that can’t be replaced. As a race, we would likely survive, but it would be in tiny, isolated self-sufficient communities that were lucky enough to escape the worst of the disasters. Maybe if we do get hit by another dinosaur-killing asteroid, the only survivors would be Innuit and people who are used to the cold and living off the sea.