Instead of teeth to catch, the birds evolved beaks to pluck and pick.Īmong the birds that began to lose teeth in favor of beaks, the way beaks form during development may have helped the evolutionary shift. While the earliest birds had teeth to nab insects and other small morsels, some bird lineages started to specialize on fruit, seeds, and other plant foods. Paleontologists have noticed that some dinosaur groups, including birds, evolved beaks and lost teeth as they became more herbivorous. Rather than flight, food might have given birds an evolutionary nudge towards toothless beaks as ancient avians thrived among other dinosaurs. “Older hypotheses focused on the idea of weight reduction for flight,” says University of Texas at Austin paleontologist Grace Musser, but the discovery that some toothed birds were strong fliers has led researchers back to the drawing board. Given that most birds fly, adaptation to the air seemed like a possibility. The question is what evolutionary pressures pushed birds to lose teeth when teeth seem so useful. And some of these toothed birds eventually lost their teeth, plucking up their meals with toothless beaks instead. For tens of millions of years after Archaeopteryx, toothed birds continued to thrive and evolve alongside their dinosaurian relatives. The very first bird, the 150 million-year-old Archaeopteryx, initially confounded 19th century naturalists because it had teeth. The happenstances of evolution had given birds a lucky break, the key events set in motion long before the asteroid struck.Īll living birds have toothless beaks, but this wasn’t always so. But of these groups, it was only the beaked birds that survived. The end of the Cretaceous boasted an entire array of birds and bird-like reptiles. “There has been a lot of discussion about what enabled modern-type birds to survive the K-Pg extinction while other birds groups, non-avian dinosaurs, and even pterosaurs perished,” says Royal BC Museum paleontologist Derek Larson. The geologic break between the two is called the K-Pg boundary, and beaked birds were the only dinosaurs to survive the disaster. All told, more than 75 percent of species known from the end of the Cretaceous period, 66 million years ago, didn’t make it to the following Paleogene period. Then the intensity of the heat pulse gave way to a prolonged impact winter, the sky blotted out by soot and ash as temperatures fell. Some of the debris thrown into the atmosphere returned to Earth, the friction turning the air into an oven and sparking forest fires as it landed all over the world. An asteroid more than 6 miles across struck what’s now the Yucatan Peninsula, triggering the fifth mass extinction in the world’s history. The entire reason paleontologists make that split is because of a catastrophe that struck 66 million years ago. With hindsight, birds can be categorized as avian dinosaurs and all the other sorts-from Stegosaurus to Brontosaurus-are non-avian dinosaurs. For more than 80 million years, birds of all sorts flourished, from loon-like swimmers with teeth to beaked birds that carried streamer-like feathers as they flew. About 150 million years ago, in the Jurassic, the first birds evolved from small, feathery, raptor-like dinosaurs, becoming another branch on the dinosaur family tree. But the connection is still there, all the way down to the bone. A pigeon or a penguin doesn’t look much like a Tyrannosaurus.
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