Steve Brusatte

So birds are nested, they're ensconced within the reptile family tree.

They are a heavily modified reptile.

This is simply based

on what we know today and the DNA of animals today.

And it is some of the strongest, most convincing evidence out there for anybody who maybe is doubting, could birds really have evolved from dinosaurs?

Are birds really some type of weird reptile?

How do you get a bird from something like a lizard or a crocodile?

Look at the genetics.

Birds are smack right in the middle of that reptile family tree.

There are fossils of tyrannosaurs, early cousins of T. rex, with feathers.

These were big top-of-the-food-chain animals.

But these were very simple feathers.

They were feathers that looked a lot like hair, just little strands, tufty, fluffy little strands.

They got longer, they started to branch out, they went from hairs to brushes, they started to line up on the arms, they started to form wings.

But even the very first wings that we see in dinosaurs, they're too small to have been used for flying.

The first wings appear on dinosaurs that are maybe the size of sheep up to about the size of horses, and those wings are no bigger than a laptop screen.

What were they used for?

We don't know, but probably display to attract mates and intimidate rivals.

And so what it really looks like is that these different components of the bird blueprint, they evolved one by one over tens of millions of years of dinosaur evolution for other reasons.

And then it just so happened that you had feathers that had probably originally evolved for insulation to keep these dinosaurs warm.