50 years ago, the dinosaurs’ demise was still a mystery
Excerpt from the July 22, 1972 issue of Science News
Fifty years ago, scientists thought dinosaurs’ warm blood or soft eggs may have caused the reptiles to die out (illustration of a partially buried dinosaur skeleton shown). Now, mounting evidence points to a killer asteroid impact.
MARK GARLICK/Science Photo Library/Getty Images
What did in the dinosaurs: Warm blood or soft eggs? — Science News, July 22, 1972
Dinosaurs might have been endothermic, or warm-blooded…. The combination of large size, endothermy and naked skin may explain the extinction of dinosaurs. About 65 million years ago there was a sharp drop in temperature…. Dinosaurs, lacking skin insulation and too large to burrow underground … could not survive. Meanwhile, evidence has come that … the shells [of their eggs] became progressively thinner … too fragile to support the growing embryo.
Update
Some dinosaurs may have been warm-blooded and some could have laid soft-shelled eggs (SN: 7/12/14, p. 6). But neither trait led to the reptiles’ demise. In the late 1970s, geologists proposed that an asteroid strike triggered a mass extinction (1/25/92, p. 56), killing more than 75 percent of life on Earth. That theory is now widely accepted. Scientists have even found the killer’s calling card: a crater about 180 kilometers wide on the coast of the Yucatán Peninsula in Mexico. The asteroid probably crash landed there in the springtime 66 million years ago, fossils hint (SN: 3/26/22, p. 8).
