How Birds Survived the Mass Extinction That Killed Most Dinosaurs

How did birds survive while most dinosaurs went extinct?

Short answer: Birds are actually living dinosaurs. They evolved from certain meat-eating theropod dinosaurs about 160 million years ago and lived alongside other dinosaurs for roughly 100 million years.

What happened 66 million years ago?

An enormous asteroid struck near what is now the coast of Mexico about 66 million years ago. The impact caused immediate devastation — huge earthquakes, tsunamis and a pulse of heat that started giant wildfires. In the months that followed, dust, soot and debris filled the atmosphere and greatly reduced sunlight, making it hard for plants to grow.

Why did some birds survive?

Fossils show that early birds came in several types: some still had teeth, while others already had toothless beaks. After the asteroid event, the fossil record indicates toothed bird species disappeared while many beak-bearing, toothless lineages persisted. Scientists offer several plausible reasons why:

• Dietary flexibility: Many toothless birds could eat seeds, nuts and fruits. Seeds and buried plant foods may have been more available than live prey when ecosystems collapsed.
• Small size and flight: Small bodies, the ability to fly or glide, and the capacity to hide or move between habitats probably helped some birds find refuges and scarce resources.
• Reproductive and life-history traits: Faster breeding or nesting behaviors may have enabled quick population recovery compared with larger, slower-breeding animals.
• Luck and habitat: Some species simply lived in places less affected by the worst conditions or happened to have the right combination of traits at the right time.

Importantly, no single explanation is proven. Scientists build hypotheses from fossils, geology and—where possible—ancient DNA, then test them as new evidence emerges. The idea that toothless beaks and a seed- or fruit-based diet helped some birds survive is one leading explanation, but researchers continue to refine the story.

Science in action: Researchers act like detectives, piecing together clues from rocks and fossils. As new discoveries are made, our understanding of why birds survived and most other dinosaurs did not will continue to improve.

If you have a question for an expert, send it to CuriousKidsUS@theconversation.com. This article is based on work by Chris Lituma at West Virginia University and is republished from The Conversation.