What did within the dinosaurs: Warm blood or smooth eggs? — Science News, July 22, 1972
Dinosaurs may need been endothermic, or warm-blooded…. The mixture of huge dimension, endothermy and bare pores and skin could clarify the extinction of dinosaurs. About 65 million years in the past there was a pointy drop in temperature…. Dinosaurs, missing pores and skin insulation and too massive to burrow underground … couldn’t survive. Meanwhile, proof has come that … the shells [of their eggs] grew to become progressively thinner … too fragile to assist the rising embryo.
Update
Some dinosaurs could have been warm-blooded and a few might have laid soft-shelled eggs (SN: 7/12/14, p. 6). But neither trait led to the reptiles’ demise. In the late Nineteen Seventies, geologists proposed that an asteroid strike triggered a mass extinction (1/25/92, p. 56), killing greater than 75 p.c of life on Earth. That principle is now extensively accepted. Scientists have even discovered the killer’s calling card: a crater about 180 kilometers huge on the coast of the Yucatán Peninsula in Mexico. The asteroid in all probability crash landed there within the springtime 66 million years in the past, fossils trace (SN: 3/26/22, p. 8).