Today, about 10,000 bird species exist worldwide. But there are debates that the exact number could almost be twice that. These warm-blooded vertebrates are well-known for their colorful plumage, lightweight, smooth feathers for flight, harmonious songs, and amusing behaviors.
But did you know that modern-day birds actually evolved from dinosaurs?
Yes. You read that right.
Birds are the only dinosaurs left since an asteroid called Chicxulub impactor struck the Earth 66 million years ago off the coast of the Gulf of Mexico. This phenomenon wiped out about 75% of animal and plant species, including all non-avian dinosaurs (any dinosaur that’s not a bird).
Only about 20% survived, including the dromaeosaurs, or the distinct group of dinosaurs upon which birds descended. They are a family of feathered theropod dinosaurs that include velociraptors.
Now you might wonder how certain avian dinosaurs, which we now know as birds, survived while other dinosaurs went extinct.
To figure out this long-standing mystery, scientists specializing in bird evolution pieced together evidence like fossils. And although they have no definite answers yet, they have hypotheses for now.
Some scientists believe that how the birds that lived with dinosaurs survived the asteroid ‘apocalypse’ has something to do with teeth.
It was known that before, some avian dinosaurs had teeth, while others did not. And they discovered that most birds that kept living or survived were toothless.
After the asteroid struck the Earth, it triggered a “mega-earthquake” that lasted weeks to months and massive tsunamis. This also caused enormous wildfires because of the impact and threw vast amounts of soot into the atmosphere. Because of this, the dust in the air blocked the sun, which hindered the plants from growing.
Many animal species, especially those that ate plants and other animals, died because much less food was available. However, the early toothless birds relied on plant-based food, such as seeds, fruits, and nuts. Since they didn’t have teeth, they didn’t depend on eating others animals.
Scientists think that it’s plausible that early toothless birds pecked the ground to look for nuts or buried seeds to eat. This might be why they survived the asteroid impact as a species.
Moreover, others believed that another reason why early avian dinosaurs survived was that they were ground-dwellers. This means that the animal species live predominantly or entirely on land. However, there are debates saying it’s because of their flying ability.
However, there is still no concrete explanation with backed evidence for these hypotheses. There could also be other factors that allowed them to keep living while others perished.
So, for now, scientists will collect more information on fossils, ancient DNA, and rocks to gather more evidence and find out how birds survived and dinosaurs didn’t.