I’m not going to say that the giant asteroid that killed the dinosaurs wasn’t bad. It was bad. Just a real unpleasant Wednesday (or whatever) for a whole bunch of just-minding-their-own-business dinosaurs.
But it wasn’t too too bad, in the grand scheme of things.
Lots of creatures survived that asteroid, 66 million years ago on what may or may not have been a Wednesday. Fish survived. Insects survived. Mammals survived, crawled out of their burrows, and took over the world. And, despite what you’ve heard, dinosaurs survived.
Now they’re called birds.
Everybody knows by now that dinosaurs and birds are closely related and that lots of dinosaurs had feathers. Feathers were modified reptile scales, and could be fluffed up to help keep a dinosaur warm, flashed around to impress a mate, or eventually, used for flight.
Birds weren’t the first animals to fly. It’s thought that insects could fly early on in their evolutionary history, about 400 million years ago. Reptiles called pterosaurs were the first vertebrates to fly, taking to the skies on wings of skin stretching between their ankles and a highly modified fourth finger. Some pterosaurs grew to be the biggest flying creatures the Earth has ever known, including quetzalcoatlus and its more than 40-foot wingspan.
Modern birds were already evolving during the height of the Age of the Dinosaurs. The earliest known dinosaur that used feathers for powered flight was archaeopteryx, from 150 million years ago. About the size of a modern crow, archaeopteryx still had many reptilian features, including sharp teeth, claws, and a long bony tail.
Lighter bodies helped these dinosaurs fly better, and so eventually certain adaptations took hold which helped dinosaurs lighten the load. Eoconfuciusornis, from 120 million years ago, had evolved long tail feathers that took the place of its bony reptile tail and had replaced its heavy jaws and teeth with a strong, light beak.
By the time of that unpleasant asteroid, 66 million years ago, dino-birds had evolved into a number of types that are still around today, including those that would become chickens, those that would become ducks, those that would become ostriches, and a small group that would become pretty much everything else.
One feature of those “everything else” birds was a special arrangement of their toes: three in the front and one on the back. This set-up allowed for a strong grip around branches, helping these birds to perch in the safety of trees. It was a successful adaptation, and these perching birds, called passerines, evolved into all kinds of different forms. Today there are more than 6,500 different species of passerines around the world, more than half of all known bird species.
Some passerines became highly specialized, like the hummingbirds that zip around drinking nectar, or the extravagant birds-of-paradise. Others became generalists, including a group of small-billed birds that found their niche in forests around the world. Some members of this noisy, active, and social group developed bold black-and-white head patterns: they became chickadees.
Different populations of chickadees evolved slight differences and became distinct species, including the mountain chickadee in the Rockies, the chestnut-backed chickadee on the West Coast, and the black-capped chickadee in the Northeast. That particular bird charmed its way into the hearts of early Mainers, who adopted it as the state’s official bird in 1927.
Scientists aren’t sure when dinosaurs stopped and birds began, mostly because dinosaurs didn’t stop. Believe it or not, the black-capped chickadee at your feeder and on your license plate is a direct descendent of some of the fiercest creatures in Earth’s history.
Nick Lund of Cumberland is outreach and network manager at Maine Audubon. He has written about nature for the National Audubon Society, Down East, National Parks Magazine, The Washington Post, and others. He can be found online at TheBirdist.com and on Twitter @TheBirdist.
