This impactor was in the same size class as the one that wiped out the dinosaurs.
Yet it didn't cause a major extinction event.
IMHO this is because the Chixulub impact was on shallow water. Imagine a 60 mile wide white hot crater with sea water pouring in from all sides! It's a recipe for steam cleaming a large portion of a planet...
Or maybe the Chixulub event did not wipe out the dinosaurs. This event is alledged to be bigger and yet did no or little damage on a plantary scale? hmmmm, something does not cumpute.