Orcas .. or killer whales .. are fairly vicious creatures. They have a habit of mauling seals for fun (nibbling on them, throw them in the air, dismember, throw, and so on). Sometimes they eat them afterwards, other times they just go on their merry way only to return when the seals again think it's safe to return to the waters .. A pair of orcas are at the ready, and this time they're hungry. That won't stop them from "playing" with their food, though. There are a few videos out there in internet land. They're not for the faint of heart. In one video an orca deliberately slides all the way up on the beach to snatch a seal, wiggle it's way back to the water and throw the seal to it's buddy. Nasty stuff.
While I don't believe the dinosaurs were killed overnight, I'm certain the impact in Mexico was big enough to start a chain reaction that, though long in its execution, gradually made the planet uninhabitable for those of the dinosaurs that weren't able to adapt quickly enough to their relatively fast changing environment. It would seem the largest of them were the losers, as God, in my mind, had intended. The smaller ones (reptiles, various insects, fish, etc.) managed to find ways to make do, thus surviving.