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Although smaller organisms waited out the extinction better than larger ones, they still perished to some degree as well. Several types of microbiota were wiped from the planet, as well as ammonites and types of fish. Several groups of mammal often suffered heavy losses. It is possible that one of these groups were a main food source for small carnivores, and when they became extinct, so did those dinosaurs. Styracosaurus Rider (Speak to the Rider, your Lord and Master) {Look upon my servants} 20:24, November 13, 2011 (UTC)

Microraptorines would have fed off the kind of mammals we see surviving the event- and animals like crocodiles and choristoderes survived well despite major fish losses. HolbenilordTalk 20:29, November 13, 2011 (UTC)
That is true, but while many groups of smaller animals became extinct not all of them did. It would be perfectly feasible for crocodiles and similar animals to survive. As for microraptorines...we can't be sure of their exact diets, even if we have skeletons located inside their stomachs. Diets were probably very varied, and a single type of mammal may not have sustained them without nutritional deficiencies. Styracosaurus Rider (Speak to the Rider, your Lord and Master) {Look upon my servants} 20:34, November 13, 2011 (UTC)
The diversity in mammals we see was not as great as that we see now, but it was far more than most think. The nutritional differences would not be particularly large- mainly the differences between oppurtunistic scavengers and carnivores, as well as insectivores and a few herbivores. Many insects survived, which provided a food source for the predominant insectivorous mammals. HolbenilordTalk 20:38, November 13, 2011 (UTC)