Which came first?

Look: Dinosaur embryo appears freakishly like a chicken in an egg

Lida Xing

Shutterstock

Dinosaurs are thought to be the ancestors of today’s birds.

Emily Willoughby/Stocktrek Images/Stocktrek Images/Getty Images

Many prehistoric beasts shared traits with avian species today: They hatched from eggs, had beaks, and were covered in feathers.