[ahrdyggd] What killed the dinosaurs?

There are weirdly (at least) two well-supported theories:

The huge Chicxulub impact happened at the right time.

The Deccan traps indicate massive volcanism at the right time.

Either of these alone could have caused mass extinction.  Both are rare events, so it seems a very strange coincidence that they should both occur nearly simultaneously.

Perhaps the impact caused the volcanism on the other side of the world via seismic focusing, or perhaps another impact around the same time hit India.  (Shoemaker-Levy 9 demonstrated how multiple impacts are not unreasonable.)  However, the Deccan traps seem explainable as normal activity of the Reunion hotspot.  Maybe the second impact created the hotspot?  One could imagine an impact permanently creating a weak spot in the crust which magma continues to exploit to this day.  This could be disproven if there is geological evidence that the Reunion hotspot was operating before the K-Pg extinction.  (Hopefully such evidence hasn't gotten subducted under the Himalayas already.)  Or it could be proven by evidence of a giant impact buried beneath the Deccan traps.

Perhaps neither impacts alone nor volcanism can cause mass extinction; it was truly the freak occurrence of both simultaneously that killed off the dinosaurs.