Cenozoic Period

Tiny fragments likely stayed in the atmosphere, possibly blocking part of the sun's ray for months or years. With less sunlight, plants and the animals dependent on them would have died, Kruk said. Furthermore, the reduced sunlight would have lowered global temperatures, impairing large active animals with high-energy needs, she said.

"Smaller, omnivorous terrestrial animals, like mammals, lizards, turtles, or birds, may have been able to survive as scavengers feeding on the carcasses of dead dinosaurs, fungi, roots and decaying plant matter, while smaller animals with lower metabolisms were best able to wait the disaster out," Kruk said. 

There is also evidence that a series of huge volcanic eruptions at the Deccan traps, located along the tectonic border between India and Asia, began just before the K-Pg event boundary. It is likely that these regional catastrophes combined to precipitate a mass extinction.