September 19, 2025

Have you ever wondered how huge flightless birds like ostriches, emus, and rheas ended up living on six different continents separated by vast oceans? It’s a puzzling mystery because these birds can’t fly! But a new study reveals an exciting story – their ancient ancestors were actually skillful flyers. Long ago, scientists believed that these birds slowly walked to their homes when all the land was one big supercontinent called Pangaea, which broke apart between 320 and 195 million years ago. However, genetics tells a different tale. The last common ancestor of these birds lived only about 79.6 million years ago, way after Pangaea had vanished. Enter Klara Widrig, a scientist at the Smithsonian National Museum of Natural History, who studied the amazing fossil of Lithornis promiscuous, an ancient bird living roughly 59 to 56 million years ago. This fossil is special because it’s perfectly preserved, giving clues about these mysterious ancestors. Widrig said, “We can't tell for sure if Lithornis was the direct ancestor of our living paleognaths — it is entirely possible that the true ancestor is yet to be discovered — but it represents our best guess as to what the ancestor would have looked like.” But the big question was—could this bird fly far? The answer came from looking at its sternum (breastbone). This bone is crucial because it anchors the powerful muscles needed for flying. Widrig’s team used 3D scans and found its sternum looked very much like those of today’s great travelers like egrets and herons, known for their long ocean flights. Peter Hosner from the Natural History Museum of Denmark said, “The great egret is a cosmopolitan species in that it travels from continent to continent.” This comparison proves that ancient paleognaths might have flown across oceans to reach new lands. So how did these flying birds become the giants who refuse to fly today? It’s a cool case of convergent evolution – where birds in different continents evolved similar flightless traits independently. Widrig explains two secrets for flightlessness: “It has to be able to get all of its food on the ground… And there can't be any predators that it would need flight to escape from.” After the mass extinction 66 million years ago, many areas had no predators, allowing these birds to enjoy life on the ground. Eventually, new predators appeared, and the birds adapted – some grew huge to scare enemies like the cassowary, while others turned super fast like the ostrich. As Widrig cheekily said, “It's not as if they got on a conference call with each other and said, 'Okay, you go to Africa and you're going to evolve into an ostrich. I'm gonna go to South America. I'm gonna evolve into a rhea.'” Nature’s playbook had other plans! To sum up, the majestic flightless birds we admire today have a surprising history of flight and adventure across the world. Next time you see an ostrich or an emu, remember their ancestors were once masters of the skies! FAQs: Q1: What are flightless birds? Flightless birds are species that cannot fly. They usually move by walking or running. Q2: Who were the ancestors of modern flightless birds? The ancestors were ancient paleognaths capable of flying long distances. They eventually evolved independently into ostriches, emus, rheas, and other flightless species.

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Tags: Flightless birds, Paleognaths, Lithornis, Bird evolution, Fossils, Convergent evolution,