NEW YORK—Dinosaurs were in decline long before an asteroid strike polished them off about 66 million years ago, a study says.
It’s the latest contribution to a long-running debate: Did the asteroid reverse the fortune of a thriving group of animals? Or were dinosaurs already struggling, and the disruptive effects of the asteroid pushed them over the edge to extinction? Or were the dinosaurs headed for oblivion anyway?
While some have argued that dinosaurs began petering out some 5 million or 10 million years before their final doom, the new paper suggests it started happening much earlier, maybe 50 million years before the asteroid catastrophe.
Workers use block and tackle to move the skeleton of one of four dinosaurs in the Cretaceous Hall of the American Museum of Natural History in New York, on Nov. 29, 1954. AP Photo/Anthony Camerano, File
