Actually this was the big event that enabled the dinosaurs to outcompete the well developed proto-mammalian Therapsids, most of whom died out at that time.
How do we know a huge meteor didn’t plow into Siberia, do its damage, and start the huge magma outpouring? Then a bacteria could have attacked the weakened life forms on earth. Perhaps it was more lethal to the therapsid branch than the dinosaur branch.
There was no huge magma outpouring — what is seen is the evidence of a long series of small magma outpourings that took place over millions of years, and had absolutely zero to do with mass extinctions.
The Hawaiian Islands are of volcanic origin, but the eruptions have mostly been of the slightly dangerous tourist-attraction variety. That’s the kind that built the Deccan Traps for instance.
The difference between the large impacts and a volcano (even a so-called “super-volcano”) is that anything a mile or more in diameter has a worldwide reach vis a vis extinctions, while a volcano might, at worst, make for pretty sunsets.