Hell Creek, 65 million years ago, two months after the K-T took place. Our fellow Quetzalcoatlus' migration was abruptly interrupted by a rock that came from outer space, visible as a small shooting star while he was flying among the birds.
After the meteor crashed, Earth’s ecosystems started to collapse. In Hell Creek, apart from the immediate deaths caused by the impact, the consecutive catastrophes wiped all most plant life. The fern prairies were the first to go, and with them the big hadrosaur herds that fed on them. Big predators perished right after a brief moment of abundance, when there were no more carcasses to sustain them. After the course of two months, only the most adaptable animals were still standing, though some of them would not live enough to see the light of day shining again through the ash clouds.
In this scenario, Ol’ Quetz tries to make a meal out of a hadrosaur carcass that is almost picked clean, but before he can even feel the taste of bone, a pair of Triceratops, with no more harem to protect nor plants to browse on, spot this last piece of hope. They are perfectly used to this kind of high-protein nutrition but in this case, is a matter or urgency. And they won’t let the pterosaur enjoy it without a fight.