Yet they breezed through the environmental crisis virtually frost-free. The Pele hypothesis, on the other hand, predicts that these are precisely the animals who should have fared well, because of their low metabolic needs. There will be a pronounced decline over along period. The inefficient ones will go out first, and then the others. That's exactly the pattern we see with the dinosaurs.
Extinction is a function of oxygen consumption and metabolic rates.
It's no surprise to Rigby that an asteroid was not the cause of dinosaur extinction. You don't do that. It effectively meant that either dinosaurs survived the asteroid, or the mammalian biochronology that we have used for a long time was in error. A certain unvarying pattern emerged over the years as he excavated several hundred tons of material prospecting for fossils in Montana. Inevitably, dinosaur remains keep cropping up in Tertiary period deposits, even though the Asteroid theory and received wisdom say Triceratops and friends should have been long gone by then.