DINO DOOMSDAY LuckyThe Ones Of all the early , only one lineage survived By Susan Milius

he asteroid strike (or was it the roiling volcanoes?) avian (in the /Aves group) by about 165 million to that triggered dino doomsday 66 million ago 150 million years ago. That left plenty of time for bona fide also brought an avian apocalypse. Birds had evolved birds to diversify before the great die-off. T by then, but only some had what it took to survive. The pioneers included the once widespread and abun- now generally accept birds as a kind of , dant , or “opposite birds.” Compared with just as people are a kind of . Much of what we think modern birds, their ball-and-socket shoulder joints were of as birdlike traits — bipedal stance, , wishbones and “backwards,” with ball rather than socket on the scapula. so on — are actually dinosaur traits that popped up here and These ancient alt birds may have gone down in the big there in the vast doomed branches of the dino tree. In that left only , amphibians, and a the diagram at right, based on one from paleontologist few lineages (including birds) among . Stephen Brusatte of the University of Edinburgh and col- There’s not a lot of information to go on. “The record leagues, anatomical icons give a rough idea of when some of of birds is pretty bad,” Brusatte says. “But I think those lin- these innovations emerged. eages that go up to the red horizontal line of doom in my fig- One branch of the dinosaur tree gradually turned arguably ure are ones that died in the impact chaos.” s

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Microraptor were relatives of the that (in ridiculously oversized form) put the screaming gotchas into Park. , alive about sanctus, an early bird living 125 million to 126 million to 120 million years ago, perched on a differ- 120 million years ago, was a mash-up. Like modern birds, ent branch than birds, but it had birdlike qualities. M. gui C. sanctus had toothless and a shortened, fused (shown) had the asymmetrical feathers with off-center called a . Yet it didn’t have a fully curved, shafts considered essential for serious . It even had keeled breastbone where powerful flight muscles attach feathers fanning off its legs, leading some paleontologists in modern birds. Its had , which is very rare in to propose that early flight had a four-winged phase. birds today. FROM LEFT: JASON BROUGHAM, JASONBROUGHAM.COM; JASONBROUGHAM.COM; BROUGHAM, JASON LEFT: FROM ALLISON ELAINE JOHNSON

26 SCIENCE NEWS | February 4, 2017 TIMELINE ADAPTED FROM S.L. BRUSATTE, J.K. O’CONNOR AND E.D. JARVIS/CURRENT BIOL. 2015; ILLUSTRATIONS FROM LEFT: UTAKO KIKUTANI; NICOLLE RAGER FULLER JURASSIC 252 237 201 174 163 145 130 120 100 6 6 survive. it did not line was, whole the as Successful teeth. had It also tail feathers. long and down soft feathers, ago),years flight-capable big sparrow-sized with was P. illustrated here, cies fengningensis spe The Period. Cretaceous the during bunch diverse 3 Million years ago Amphibians

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