The Majority of Mammals survived, with only a few going extinct, which would mean, there is still a large food source available, and even if there was a lack of food, that wouldnt explain why the Herbivores and Omnivores went extinct.
Without any dinosaur DNA, we have no idea why they went extinct, whether it was something that was effected within their genes, we have no way of knowing, and to be honest, i prefer it that way, it still preserves the mystery around them.
Mammals were able to adapt which allowed them to survive; dinosaurs couldn't.
Except the Dinosaurs could adapt, considering they were around for 160 million years, and went through an extinction period between the Triassic and Jurassic periods, they came out unscathed, Meteor impacts would of only had an effect for around 10 years, and the fossil record shows that at the dates of major impacts, dinosaurs were around after the 10 years.
I'm not disputing that the Meteors didnt have an effect, its clear that they did, however with the species that did survive, such as the mammals and fish, crocodiles and sharks, i just have to question whether it was a fact of them being 'unable to adapt'. If you look at a the dinosaurs that could fly, the small ones, they would have essentially the same diet as birds, eating small lizards, bugs, etc. Yet they went extinct and a number of modern day birds that were alive in that period didnt. Even with the big dinosaurs, plenty of fish survived, yet the fish eaters similar to Baronyx, and Spinosaurus (Although these were extinct at the beginning of the cretaceous) they died out, so its clearly not the food source, for some, and the effects of Impact would be minimal, for a large area outside the crater.
TBH, im just blabbering now, although there is no clear reason why the Dinosaurs did go extinct