The Bird You See Outside? It's a Modern-Day Dinosaur

Have you ever visited the Field Museum and stood in awe of the huge dinosaur skeletons on display? The most famous of the museum’s dinosaurs, Sue, a Tyrannosaurus rex, might not remind you of the birds we see today, but they are related.

A great blue heron. (Photo courtesy of Alan Keahey)

That’s right — the birds of today descended from dinosaurs. About 66 million years ago a massive asteroid hit Earth and killed off many of the animals living on our planet. But some dinosaurs survived, and the birds we see today evolved from those creatures.


Scientists today believe birds are the last living dinosaurs on Earth. This is because birds have physical features, like feathers, and behaviors, like building nests, that first occurred in dinosaurs.


If you traced the family tree of a bird from today to its origin, it would start with a dinosaur called Archaeopteryx. The Archaeopteryx weighed about 2 pounds. It didn't really resemble any bird we see today, but it did have some important features, including wings, feathers and a wishbone. 


Scientists now know birds evolved from a group of dinosaurs called theropods. The theropods included the mighty T. rex, although birds evolved from smaller theropods.

When the asteroid hit 66 million years ago, most dinosaurs went extinct, but the bird-like dinosaurs survived. In the millions of years since, birds have continued to evolve. This explains why we have so many different bird species today.


We know a lot today about the link between birds and dinosaurs because of the discovery of hundreds of dinosaur fossils. The fossils, found mostly in China, confirmed scientists’ idea that some dinosaurs were warm blooded and had feathers.


While we know birds and dinosaurs are related, many mysteries remain. Among these is why some dinosaurs — including those related to birds — survived the extinction. Scientists have many ideas. It may have had to do with their ability to fly, their diet, their small size or even their nesting ability. Some researchers believe a combination of these factors allowed them to survive and evolve into the birds we know today.

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