After the asteroid hit. The extinction of the dinosaurs is, in certain ways, the pop science equivalent of the falls of great houses in ancient literature. It’s fascinating and it accommodates dozens of plausible explanations and hundreds of possible ones. Good for business.
“It became cold, I mean, really cold,” says Brugger. Global annual mean surface air temperature dropped by at least 26 degrees Celsius. The dinosaurs were used to living in a lush climate. After the asteroid’s impact, the annual average temperature was below freezing point for about 3 years. Evidently, the ice caps expanded. Even in the tropics, annual mean temperatures went from 27 degrees to mere 5 degrees. “The long-term cooling caused by the sulfate aerosols was much more important for the mass extinction than the dust that stays in the atmosphere for only a relatively short time. It was also more important than local events like the extreme heat close to the impact, wildfires or tsunamis,” says co-author Georg Feulner who leads the research team at PIK. It took the climate about 30 years to recover, the scientists found. Paper. (paywall) – Julia Brugger, Georg Feulner, Stefan Petri. Baby, it’s cold outside: Climate model simulations of the effects of the asteroid impact at the end of the Cretaceous. Geophysical Research Letters, 2016; DOI: 10.1002/2016GL072241More.
There has been a long-running debate about whether dinosaurs were exothermic (cold-blooded like reptiles) or endothermic (warm-blooded like mammals). If ambient temperature changes brought about the entire order’s extinction, it should count in favor of the former view.
That said, there are many hypotheses about what did in the dinosaurs, including the one that they were already failing before the catastrophe. In any event, we will probably not be able to understand evolution in a historical way without much better knowledge of stasis and extinction. That’s what happens when it becomes a history not a philosophy.
In the past, the field has been littered with speculations such as that dinosaurs were dumber than mammals and did not look after their young. But we now know that some dinosaurs did look after their young and that the capacity to do so is much older than formerly thought. Also that placental mammals are not uniformly smarter than all other life forms.
See also: Extinction: Had the dinosaurs been dying out before the big K-T extinction?
Dino diminuendo (They were dying out before the asteroid hit.) That might help account for why all dinosaurs disappeared but only a large proportion of other vertebrates.
Smoking did not kill the dinosaurs, but dark matter might have contributed
Dinosaurs doomed by egg-laying?
Size helped largest dinos survive longer?
Do mass extinctions happen every 26 million years or so?
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