Every bird you’ve ever seen— every pigeon at a bus stop, every penguin at the zoo— is a living, breathing dinosaur. Birds are the only group of dinosaurs that survived the mass extinction caused when an asteroid hit the Earth 66 million years ago. A fossil called Archaeopteryx, with feathers, hollow bones, clawed wings, fifty tiny teeth, and a long bony tail, is the earliest known dinosaur that also qualifies as a bird. Adult Unisex Sizes.