After 150 million years, the most successful empire in the history of Planet Earth finally collapsed 66 million years ago. A five-mile-wide space bomb--there's still disagreement as to whether it was an asteroid or a comet--hit on one of the worst places imaginable--a Yucatan Peninsula high in concentrations of two kinds of elements that are known to have climate-altering capabilities--carbon and sulfur. From the sulfur, life on Earth had to endure periods of acid rain and a decade of intense cold. From the carbon, a decade of intense cold was followed by centuries if not millennia of intense heat.
And now, thanks to a discovery in Hell Creek of a fossilized tsunami junk pile by Robert DePalma, we might have finally found the season in which the northern hemisphere was under when Chicxulub hit. Based on the remains of juvenile sturgeons and paddlefish, DePalma surmised that the fall of the dinosaur empire most likely started in the autumn.
I won't list you the 75% of the plant and animal species that died out in this event, for not only is it long, it's also not detailed among some groups. But when you consider that many climate-sensitive clades, like amphibians, did survive this catastrophe, it'd make sense that Chicxulub most likely hit the Yucatan during the fall, when countless plant and animal species were shutting down for the upcoming winter.
So with that in mind, how different would the outcome of the fall of the dinosaur empire be if Chicxulub hit the Yucatan at a different season--say, for example, summer?