Insects inherit the earth ...

In an intriguing report about a soon-to-be-published hypothesis, Forget the meteorites - it was insects that did for the dinosaurs there seems to be credible evidence that longer term ecological factors could have had a lot to do with the demise of dinosaurs.
"Our research with amber shows that there were evolving, disease-carrying vectors in the Cretaceous [period], and that at least some of the pathogens they carried infected reptiles. This clearly fills in some gaps regarding dinosaur extinctions.'
In the gut of one biting insect preserved in amber - fossilised tree sap - from that era, the team has found the pathogen that causes the parasitic disease leishmaniasis, and in another they found a type of malaria parasite that infects birds and lizards. By inspecting fossilised dinosaur faeces, the team also found parasitic microbes that are carried by insects.
Apart from spreading disease, the insects were busy pollinating flowering plants.
These gradually took over from seed ferns, cycads and gingkoes. If herbivorous dinosaurs could not adapt to this new diet they would have gone hungry."
And from there, the effects would work up the food chain.